Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

75 files changed, 5579 insertions, 0 deletions

diff --git a/dom/fs/test/common/.eslintrc.js b/dom/fs/test/common/.eslintrc.js
new file mode 100644
index 0000000000..d805cf6e0f
--- /dev/null
+++ b/dom/fs/test/common/.eslintrc.js
@@ -0,0 +1,14 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+module.exports = {
+  globals: {
+    Assert: true,
+    exported_symbols: true,
+    require_module: true,
+    Utils: true,
+  },
+};
diff --git a/dom/fs/test/common/dummy.js b/dom/fs/test/common/dummy.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/dom/fs/test/common/dummy.js
diff --git a/dom/fs/test/common/mochitest.toml b/dom/fs/test/common/mochitest.toml
new file mode 100644
index 0000000000..3da39b96b8
--- /dev/null
+++ b/dom/fs/test/common/mochitest.toml
@@ -0,0 +1,15 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+[DEFAULT]
+support-files = [
+  "nsresult.js",
+  "test_basics.js",
+  "test_fileSystemDirectoryHandle.js",
+  "test_syncAccessHandle.js",
+  "test_writableFileStream.js",
+]
+
+["dummy.js"]
+skip-if = ["true"]
diff --git a/dom/fs/test/common/moz.build b/dom/fs/test/common/moz.build
new file mode 100644
index 0000000000..65d62c9cda
--- /dev/null
+++ b/dom/fs/test/common/moz.build
@@ -0,0 +1,21 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+MOCHITEST_MANIFESTS += [
+    "mochitest.toml",
+]
+
+XPCSHELL_TESTS_MANIFESTS += [
+    "xpcshell.toml",
+]
+
+TESTING_JS_MODULES.dom.fs.test.common += [
+    "nsresult.js",
+    "test_basics.js",
+    "test_fileSystemDirectoryHandle.js",
+    "test_syncAccessHandle.js",
+    "test_writableFileStream.js",
+]
diff --git a/dom/fs/test/common/nsresult.js b/dom/fs/test/common/nsresult.js
new file mode 100644
index 0000000000..6e59b947a1
--- /dev/null
+++ b/dom/fs/test/common/nsresult.js
@@ -0,0 +1,9 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+const nsresult = {
+  NS_ERROR_NOT_IMPLEMENTED: Cr.NS_ERROR_NOT_IMPLEMENTED,
+};
+exported_symbols.nsresult = nsresult;
diff --git a/dom/fs/test/common/test_basics.js b/dom/fs/test/common/test_basics.js
new file mode 100644
index 0000000000..f1cb1c222e
--- /dev/null
+++ b/dom/fs/test/common/test_basics.js
@@ -0,0 +1,375 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+// This test must be first, since we need the actor not to be created already.
+exported_symbols.testGetDirectoryTwice = async function () {
+  const promise1 = navigator.storage.getDirectory();
+  const promise2 = navigator.storage.getDirectory();
+
+  await Promise.all([promise1, promise2]);
+
+  Assert.ok(true, "Should not have thrown");
+};
+
+exported_symbols.testGetDirectoryDoesNotThrow = async function () {
+  await navigator.storage.getDirectory();
+
+  Assert.ok(true, "Should not have thrown");
+};
+
+exported_symbols.testGetDirectoryKindIsDirectory = async function () {
+  const root = await navigator.storage.getDirectory();
+
+  Assert.equal(root.kind, "directory");
+};
+
+exported_symbols.testDirectoryHandleStringConversion = async function () {
+  const root = await navigator.storage.getDirectory();
+
+  Assert.equal(
+    "" + root,
+    "[object FileSystemDirectoryHandle]",
+    "Is directoryHandle convertible to string?"
+  );
+};
+
+exported_symbols.testNewDirectoryHandleFromPrototype = async function () {
+  const root = await navigator.storage.getDirectory();
+
+  try {
+    Object.create(root.prototype);
+    Assert.ok(false, "Should have thrown");
+  } catch (ex) {
+    Assert.ok(true, "Should have thrown");
+    Assert.ok(ex instanceof TypeError, "Threw the right error type");
+  }
+};
+
+exported_symbols.testIsSameEntryRoot = async function () {
+  const root = await navigator.storage.getDirectory();
+  try {
+    await root.move(root);
+    Assert.ok(false, "root should not be movable");
+  } catch (ex) {
+    Assert.ok(true, "root isn't movable");
+  }
+};
+
+exported_symbols.testDirectoryHandleSupportsKeysIterator = async function () {
+  const root = await navigator.storage.getDirectory();
+
+  const it = await root.keys();
+  Assert.ok(!!it, "Does root support keys iterator?");
+};
+
+exported_symbols.testKeysIteratorNextIsCallable = async function () {
+  const root = await navigator.storage.getDirectory();
+
+  const it = await root.keys();
+  Assert.ok(!!it, "Does root support keys iterator?");
+
+  const item = await it.next();
+  Assert.ok(!!item, "Should return an item");
+};
+
+exported_symbols.testDirectoryHandleSupportsValuesIterator = async function () {
+  const root = await navigator.storage.getDirectory();
+
+  const it = await root.values();
+  Assert.ok(!!it, "Does root support values iterator?");
+};
+
+exported_symbols.testValuesIteratorNextIsCallable = async function () {
+  const root = await navigator.storage.getDirectory();
+
+  const it = await root.values();
+  Assert.ok(!!it, "Does root support values iterator?");
+
+  const item = await it.next();
+  Assert.ok(!!item, "Should return an item");
+};
+
+exported_symbols.testDirectoryHandleSupportsEntriesIterator =
+  async function () {
+    const root = await navigator.storage.getDirectory();
+
+    const it = await root.entries();
+    Assert.ok(!!it, "Does root support entries iterator?");
+  };
+
+exported_symbols.testEntriesIteratorNextIsCallable = async function () {
+  const root = await navigator.storage.getDirectory();
+
+  const it = await root.entries();
+  Assert.ok(!!it, "Does root support entries iterator?");
+
+  const item = await it.next();
+  Assert.ok(!!item, "Should return an item");
+};
+
+exported_symbols.testGetFileHandleIsCallable = async function () {
+  const root = await navigator.storage.getDirectory();
+  const allowCreate = { create: true };
+
+  const item = await root.getFileHandle("fileName", allowCreate);
+  Assert.ok(!!item, "Should return an item");
+
+  await root.removeEntry("fileName");
+};
+
+exported_symbols.testGetDirectoryHandleIsCallable = async function () {
+  const root = await navigator.storage.getDirectory();
+  const allowCreate = { create: true };
+
+  const item = await root.getDirectoryHandle("dirName", allowCreate);
+  Assert.ok(!!item, "Should return an item");
+
+  await root.removeEntry("dirName");
+};
+
+exported_symbols.testRemoveEntryIsCallable = async function () {
+  const root = await navigator.storage.getDirectory();
+  const removeOptions = { recursive: true };
+  const allowCreate = { create: true };
+
+  // Ensure file and directory items exists
+  await root.getFileHandle("fileName", allowCreate);
+  await root.getDirectoryHandle("dirName", allowCreate);
+  await root.removeEntry("fileName", removeOptions);
+  await root.removeEntry("dirName", removeOptions);
+  try {
+    await root.removeEntry("doesNotExist", removeOptions);
+    Assert.ok(false, "Should have thrown");
+  } catch (ex) {
+    Assert.ok(true, "Should have thrown");
+    Assert.equal(
+      ex.message,
+      "Entry not found",
+      "Threw the right error message"
+    );
+  }
+};
+
+exported_symbols.testResolveIsCallable = async function () {
+  const root = await navigator.storage.getDirectory();
+  const allowCreate = { create: true };
+  const item = await root.getFileHandle("fileName", allowCreate);
+
+  let path = await root.resolve(item);
+  Assert.equal(path.length, 1);
+  Assert.equal(path[0], "fileName", "Resolve got the right path");
+
+  await root.removeEntry("fileName");
+};
+
+exported_symbols.testFileType = async function () {
+  const root = await navigator.storage.getDirectory();
+  const allowCreate = { create: true };
+  const nameStem = "testFileType";
+  const empty = "";
+
+  const extensions = [
+    "txt",
+    "jS",
+    "JSON",
+    "css",
+    "html",
+    "htm",
+    "xhtml",
+    "xml",
+    "xhtml+xml",
+    "png",
+    "apng",
+    "jPg",
+    "Jpeg",
+    "pdF",
+    "out",
+    "sh",
+    "ExE",
+    "psid",
+    "EXE ",
+    " EXE",
+    "EX\uff65",
+    "\udbff\udbff\udbff",
+    // XXX: Invalid surrogate combos like "\udc00\udc00\udc00" may map to the same names impacting cleanup.
+    "js\udbff",
+    "\udc00js",
+    "???",
+    "\root",
+    empty,
+    "AXS",
+    "dll",
+    "ocx",
+    "1",
+    "ps1",
+    "cmd",
+    "xpi",
+    "swf",
+  ];
+
+  const expectedTypes = [
+    "text/plain",
+    "application/javascript",
+    "application/json",
+    "text/css",
+    "text/html",
+    "text/html",
+    "application/xhtml+xml",
+    "text/xml",
+    empty,
+    "image/png",
+    "image/apng",
+    "image/jpeg",
+    "image/jpeg",
+    "application/pdf",
+    empty,
+    "application/x-sh",
+    "application/octet-stream",
+    empty,
+    empty,
+    empty,
+    empty,
+    empty,
+    empty,
+    empty,
+    empty,
+    empty,
+    empty,
+    "application/olescript",
+    "application/x-msdownload",
+    "application/octet-stream",
+    empty,
+    empty,
+    "text/plain",
+    "application/x-xpinstall",
+    "application/x-shockwave-flash",
+  ];
+
+  Assert.equal(extensions.length, expectedTypes.length);
+
+  await Promise.all(
+    extensions.map(async (ext, i) => {
+      const fileName = nameStem + "." + ext;
+      const fileHandle = await root.getFileHandle(fileName, allowCreate);
+      const fileObject = await fileHandle.getFile();
+      Assert.equal(fileObject.name, fileHandle.name);
+      Assert.equal(fileObject.type, expectedTypes[i]);
+      await root.removeEntry(fileName);
+    })
+  );
+};
+
+exported_symbols.testContentTypeChangesOnFileMove = async function () {
+  const allowCreate = { create: true };
+  const root = await navigator.storage.getDirectory();
+  const oldName = "testFile.txt";
+  const oldType = "text/plain";
+  const subdir = await root.getDirectoryHandle("subdir", allowCreate);
+
+  const fileHandle = await root.getFileHandle(oldName, allowCreate);
+
+  async function checkMove(newName, newType) {
+    Assert.equal(fileHandle.name, newName, "Has filename changed?");
+    {
+      const fileObject = await fileHandle.getFile();
+      Assert.equal(fileObject.name, newName, "Is the fileobject renamed?");
+      Assert.equal(fileObject.type, newType, "Is the fileobject type updated?");
+    }
+  }
+
+  async function restoreTest() {
+    await fileHandle.move(root, oldName);
+    await checkMove(oldName, oldType);
+  }
+
+  // No name change
+  await checkMove(oldName, oldType);
+  await fileHandle.move(subdir);
+  await checkMove(oldName, oldType);
+  await restoreTest();
+
+  // With name change
+
+  async function testMoveWithParams(testName, testType) {
+    async function testFileMoveCall(...combo) {
+      await fileHandle.move(...combo);
+      await checkMove(testName, testType);
+      await restoreTest();
+    }
+
+    await testFileMoveCall(subdir, testName);
+    await testFileMoveCall(root, testName);
+    await testFileMoveCall(testName);
+  }
+
+  const testParams = {
+    "testFile.json": "application/json",
+    testFile: oldType,
+    "testFile.äüö": "",
+  };
+
+  for (const [aName, aType] of Object.entries(testParams)) {
+    await testMoveWithParams(aName, aType);
+  }
+};
+
+exported_symbols.testContentTypeChangesOnDirMove = async function () {
+  const allowCreate = { create: true };
+  const root = await navigator.storage.getDirectory();
+  const oldName = "testFile.txt";
+  const oldType = "text/plain";
+  const subDirOrig = await root.getDirectoryHandle("subDirOrig", allowCreate);
+  const subDirOther = await root.getDirectoryHandle("subDirOther", allowCreate);
+  const subSubDir = await subDirOrig.getDirectoryHandle(
+    "subSubDir",
+    allowCreate
+  );
+
+  const testName = "testFile.json";
+  const testType = "application/json";
+
+  async function checkMove(newName, newType) {
+    const fileHandle = await subSubDir.getFileHandle(newName, allowCreate);
+
+    Assert.equal(fileHandle.name, newName, "Has filename changed?");
+    {
+      const fileObject = await fileHandle.getFile();
+      Assert.equal(fileObject.name, newName, "Is the fileobject renamed?");
+      Assert.equal(fileObject.type, newType, "Is the fileobject type updated?");
+    }
+  }
+
+  async function restoreTest() {
+    await subSubDir.move(subDirOrig, "subSubDir");
+    await checkMove(oldName, oldType);
+  }
+
+  await checkMove(oldName, oldType);
+
+  // No name change
+  await subSubDir.move(subDirOther, "other");
+  await checkMove(oldName, oldType);
+  await restoreTest();
+
+  // With name change
+
+  async function testDirMoveCall(...combo) {
+    await subSubDir.move(...combo);
+    await checkMove(testName, testType);
+    await restoreTest();
+  }
+
+  await testDirMoveCall(subDirOther);
+  await testDirMoveCall(subDirOther, testName);
+  await testDirMoveCall(subDirOrig, testName);
+  await testDirMoveCall(subDirOrig);
+};
+
+for (const [key, value] of Object.entries(exported_symbols)) {
+  Object.defineProperty(value, "name", {
+    value: key,
+    writable: false,
+  });
+}
diff --git a/dom/fs/test/common/test_fileSystemDirectoryHandle.js b/dom/fs/test/common/test_fileSystemDirectoryHandle.js
new file mode 100644
index 0000000000..9142e47380
--- /dev/null
+++ b/dom/fs/test/common/test_fileSystemDirectoryHandle.js
@@ -0,0 +1,196 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+exported_symbols.smokeTest = async function smokeTest() {
+  const storage = navigator.storage;
+  const subdirectoryNames = new Set(["Documents", "Downloads", "Music"]);
+  const allowCreate = { create: true };
+
+  {
+    let root = await storage.getDirectory();
+    Assert.ok(root, "Can we access the root directory?");
+
+    let it = await root.values();
+    Assert.ok(!!it, "Does root have values iterator?");
+
+    let elem = await it.next();
+    Assert.ok(elem.done, "Is root directory empty?");
+
+    for (let dirName of subdirectoryNames) {
+      await root.getDirectoryHandle(dirName, allowCreate);
+      Assert.ok(true, "Was it possible to add subdirectory " + dirName + "?");
+    }
+  }
+
+  {
+    let root = await storage.getDirectory();
+    Assert.ok(root, "Can we refresh the root directory?");
+
+    let it = await root.values();
+    Assert.ok(!!it, "Does root have values iterator?");
+
+    let hasElements = false;
+    let hangGuard = 0;
+    for await (let [key, elem] of root.entries()) {
+      Assert.ok(elem, "Is element not non-empty?");
+      Assert.equal("directory", elem.kind, "Is found item a directory?");
+      Assert.ok(
+        elem.name.length >= 1 && elem.name.match("^[A-Za-z]{1,64}"),
+        "Are names of the elements strings?"
+      );
+      Assert.equal(key, elem.name);
+      Assert.ok(subdirectoryNames.has(elem.name), "Is name among known names?");
+      hasElements = true;
+      ++hangGuard;
+      if (hangGuard == 10) {
+        break; // Exit if there is a hang
+      }
+    }
+
+    Assert.ok(hasElements, "Is values container now non-empty?");
+    Assert.equal(3, hangGuard, "Do we only have three elements?");
+
+    {
+      it = await root.values();
+      Assert.ok(!!it, "Does root have values iterator?");
+      let elem = await it.next();
+
+      await elem.value.getDirectoryHandle("Trash", allowCreate);
+      let subit = elem.value.values();
+      Assert.ok(!!elem, "Is element not non-empty?");
+      let subdirResult = await subit.next();
+      let subdir = subdirResult.value;
+      Assert.ok(!!subdir, "Is element not non-empty?");
+      Assert.equal("directory", subdir.kind, "Is found item a directory?");
+      Assert.equal("Trash", subdir.name, "Is found item a directory?");
+    }
+
+    const wipeEverything = { recursive: true };
+    for (let dirName of subdirectoryNames) {
+      await root.removeEntry(dirName, wipeEverything);
+      Assert.ok(
+        true,
+        "Was it possible to remove subdirectory " + dirName + "?"
+      );
+    }
+  }
+
+  {
+    let root = await storage.getDirectory();
+    Assert.ok(root, "Can we refresh the root directory?");
+
+    let it = root.values();
+    Assert.ok(!!it, "Does root have values iterator?");
+
+    let elem = await it.next();
+    Assert.ok(elem.done, "Is root directory empty?");
+  }
+};
+
+exported_symbols.quotaTest = async function () {
+  const storage = navigator.storage;
+  const allowCreate = { create: true };
+
+  {
+    let root = await storage.getDirectory();
+    Assert.ok(root, "Can we access the root directory?");
+
+    const fileHandle = await root.getFileHandle("test.txt", allowCreate);
+    Assert.ok(!!fileHandle, "Can we get file handle?");
+
+    const usageAtStart = await Utils.getCachedOriginUsage();
+    Assert.ok(true, "usageAtStart: " + usageAtStart);
+
+    const writable = await fileHandle.createWritable();
+    Assert.ok(!!writable, "Can we create writable file stream?");
+
+    const usageAtWritableCreated = await Utils.getCachedOriginUsage();
+    Assert.equal(
+      usageAtWritableCreated - usageAtStart,
+      0,
+      "Did usage increase when writable was created?"
+    );
+
+    const buffer = new ArrayBuffer(42);
+    Assert.ok(!!buffer, "Can we create array buffer?");
+
+    const result = await writable.write(buffer);
+    Assert.equal(result, undefined, "Can we write entire buffer?");
+
+    const usageAtWriteDone = await Utils.getCachedOriginUsage();
+    // Note: Usage should change only on close after 1824305
+    Assert.equal(
+      usageAtWriteDone - usageAtWritableCreated,
+      buffer.byteLength,
+      "Is write immediately reflected in usage?"
+    );
+
+    await writable.close();
+
+    const usageAtWritableClosed = await Utils.getCachedOriginUsage();
+
+    Assert.equal(
+      usageAtWritableClosed - usageAtWritableCreated,
+      buffer.byteLength,
+      "Did usage increase by the amount of bytes written?"
+    );
+
+    await root.removeEntry("test.txt");
+
+    const usageAtFileDeleted = await Utils.getCachedOriginUsage();
+
+    Assert.equal(
+      usageAtFileDeleted,
+      usageAtWritableCreated,
+      "Is usage back to the value before any writing when the file is removed?"
+    );
+  }
+};
+
+exported_symbols.pagedIterationTest = async function () {
+  const root = await navigator.storage.getDirectory();
+
+  for await (let contentItem of root.keys()) {
+    await root.removeEntry(contentItem, { recursive: true });
+  }
+
+  const allowCreate = { create: true };
+
+  // When half of the buffer is iterated, a request for the second half is sent.
+  // We test that the this boundary is crossed smoothly.
+  // After the buffer is filled, a request for more items is sent. The
+  // items are placed in the first half of the buffer.
+  // This boundary should also be crossed without problems.
+  // Currently, the buffer is half-filled at 1024.
+  const itemBatch = 3 + 2 * 1024;
+  for (let i = 0; i <= itemBatch; ++i) {
+    await root.getDirectoryHandle("" + i, allowCreate);
+  }
+
+  let result = 0;
+  let sum = 0;
+  const handles = new Set();
+  let isUnique = true;
+  for await (let [key, elem] of root.entries()) {
+    result += key.length;
+    sum += parseInt(elem.name);
+    if (handles.has(key)) {
+      // Asserting here is slow and verbose
+      isUnique = false;
+      break;
+    }
+    handles.add(key);
+  }
+  Assert.ok(isUnique);
+  Assert.equal(result, 7098);
+  Assert.equal(sum, (itemBatch * (itemBatch + 1)) / 2);
+};
+
+for (const [key, value] of Object.entries(exported_symbols)) {
+  Object.defineProperty(value, "name", {
+    value: key,
+    writable: false,
+  });
+}
diff --git a/dom/fs/test/common/test_syncAccessHandle.js b/dom/fs/test/common/test_syncAccessHandle.js
new file mode 100644
index 0000000000..ac7e0ef769
--- /dev/null
+++ b/dom/fs/test/common/test_syncAccessHandle.js
@@ -0,0 +1,237 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+const allowCreate = { create: true };
+
+exported_symbols.test0 = async function () {
+  let root = await navigator.storage.getDirectory();
+  Assert.ok(root, "Can we access the root directory?");
+
+  try {
+    await root.getFileHandle("test.txt");
+    Assert.ok(false, "Opened file that shouldn't exist");
+  } catch (e) {
+    dump("caught exception when we tried to open a non-existant file\n");
+  }
+};
+
+exported_symbols.test1 = async function () {
+  let root = await navigator.storage.getDirectory();
+  Assert.ok(root, "Can we access the root directory?");
+
+  const testFile = await root.getFileHandle("test.txt", allowCreate);
+  Assert.ok(!!testFile, "Can't create file");
+  let handle = await testFile.createSyncAccessHandle();
+  Assert.ok(!!handle, "Can't create SyncAccessHandle");
+  await handle.close();
+  handle = await testFile.createSyncAccessHandle();
+  Assert.ok(!!handle, "Can't create second SyncAccessHandle to same file");
+  await handle.close();
+};
+
+exported_symbols.test2 = async function () {
+  let root = await navigator.storage.getDirectory();
+  Assert.ok(root, "Can we access the root directory?");
+
+  const testFile = await root.getFileHandle("test.txt", allowCreate);
+  Assert.ok(!!testFile, "Can't open file");
+  let handle = await testFile.createSyncAccessHandle();
+  Assert.ok(!!handle, "Can't create SyncAccessHandle");
+  await handle.close();
+
+  await root.removeEntry("test.txt");
+  try {
+    handle = await testFile.createSyncAccessHandle();
+    Assert.ok(!!handle, "Didn't remove file!");
+    if (handle) {
+      await handle.close();
+    }
+  } catch (e) {
+    dump("Caught exception trying to create accesshandle to deleted file\n");
+  }
+};
+
+exported_symbols.test3 = async function () {
+  let root = await navigator.storage.getDirectory();
+  Assert.ok(!!root, "Can we access the root directory?");
+
+  let dir = await root.getDirectoryHandle("dir", allowCreate);
+  Assert.ok(!!dir, "Can we create a directory?");
+
+  // XXX not implemented yet
+  //const path = await root.resolve(dir);
+  //Assert.ok(path == ["dir"], "Wrong path: " + path);
+
+  let dir2 = await dir.getDirectoryHandle("dir", allowCreate);
+  Assert.ok(!!dir, "Can we create dir/dir?");
+
+  // XXX not implemented yet
+  //const path = await root.resolve(dir2);
+  //Assert.ok(path == ["dir", "dir"], "Wrong path: " + path);
+
+  let dir3 = await dir.getDirectoryHandle("bar", allowCreate);
+  Assert.ok(!!dir3, "Can we create dir/bar?");
+
+  // This should fail
+  try {
+    await root.getDirectoryHandle("bar");
+    Assert.ok(!dir, "we shouldn't be able to get bar unless we create it");
+  } catch (e) {
+    dump("caught exception when we tried to get a non-existant dir\n");
+  }
+
+  const testFile = await dir2.getFileHandle("test.txt", allowCreate);
+  Assert.ok(!!testFile, "Can't create file in dir2");
+  let handle = await testFile.createSyncAccessHandle();
+  Assert.ok(!!handle, "Can't create SyncAccessHandle in dir2");
+  await handle.close();
+};
+
+exported_symbols.test4 = async function () {
+  let root = await navigator.storage.getDirectory();
+  Assert.ok(!!root, "Can we access the root directory?");
+
+  const testFile = await root.getFileHandle("test.txt", allowCreate);
+  Assert.ok(!!testFile, "Can't access existing file");
+  let handle = await testFile.createSyncAccessHandle();
+  Assert.ok(!!handle, "Can't create SyncAccessHandle to existing file");
+
+  // Write a sentence to the end of the file.
+  const encoder = new TextEncoder();
+  const writeBuffer = encoder.encode("Thank you for reading this.");
+  const writeSize = handle.write(writeBuffer);
+  Assert.ok(!!writeSize);
+
+  // Read it back
+  // Get size of the file.
+  let fileSize = await handle.getSize();
+  Assert.ok(fileSize == writeBuffer.byteLength);
+  // Read file content to a buffer.
+  const readBuffer = new ArrayBuffer(fileSize);
+  const readSize = handle.read(readBuffer, { at: 0 });
+  Assert.ok(!!readSize);
+  //Assert.ok(readBuffer == writeBuffer);
+
+  await handle.truncate(5);
+  fileSize = await handle.getSize();
+  Assert.ok(fileSize == 5);
+
+  await handle.flush();
+  await handle.close();
+};
+
+exported_symbols.test5 = async function () {
+  let root = await navigator.storage.getDirectory();
+  Assert.ok(!!root, "Can we access the root directory?");
+
+  const testFile = await root.getFileHandle("test.txt", allowCreate);
+  Assert.ok(!!testFile, "Can't create file");
+  let handle = await testFile.createSyncAccessHandle();
+  Assert.ok(!!handle, "Can't create SyncAccessHandle");
+
+  try {
+    const testFile2 = await root.getFileHandle("test2.txt", allowCreate);
+    let handle2 = await testFile2.createSyncAccessHandle();
+    Assert.ok(!!handle2, "can't create SyncAccessHandle to second file!");
+    if (handle2) {
+      await handle2.close();
+    }
+  } catch (e) {
+    Assert.ok(false, "Failed to create second file");
+  }
+
+  await handle.close();
+};
+
+exported_symbols.test6 = async function () {
+  let root = await navigator.storage.getDirectory();
+  Assert.ok(root, "Can we access the root directory?");
+
+  const testFile = await root.getFileHandle("test.txt", allowCreate);
+  Assert.ok(!!testFile, "Can't get file");
+  let handle = await testFile.createSyncAccessHandle();
+  Assert.ok(!!handle, "Can't create SyncAccessHandle");
+
+  try {
+    let handle2 = await testFile.createSyncAccessHandle();
+    Assert.ok(!handle2, "Shouldn't create SyncAccessHandle!");
+    if (handle2) {
+      await handle2.close();
+    }
+  } catch (e) {
+    // should always happen
+    dump("caught exception when we tried to get 2 SyncAccessHandles\n");
+  }
+
+  // test that locks work across multiple connections for an origin
+  try {
+    let root2 = await navigator.storage.getDirectory();
+    Assert.ok(root2, "Can we access the root2 directory?");
+
+    const testFile2 = await root2.getFileHandle("test.txt");
+    Assert.ok(!!testFile2, "Can't get file");
+    let handle2 = await testFile2.createSyncAccessHandle();
+    Assert.ok(!handle2, "Shouldn't create SyncAccessHandle (2)!");
+    if (handle2) {
+      await handle2.close();
+    }
+  } catch (e) {
+    // should always happen
+    dump("caught exception when we tried to get 2 SyncAccessHandles\n");
+  }
+
+  if (handle) {
+    await handle.close();
+  }
+};
+
+exported_symbols.quotaTest = async function () {
+  const shrinkedStorageSizeKB = 5 * 1024;
+  const defaultDatabaseSize = 491520;
+
+  // Shrink storage size to 5MB.
+  await Utils.shrinkStorageSize(shrinkedStorageSizeKB);
+
+  let root = await navigator.storage.getDirectory();
+  Assert.ok(root, "Can we access the root directory?");
+
+  // Fill entire storage.
+  const fileHandle = await root.getFileHandle("test.txt", allowCreate);
+  Assert.ok(!!fileHandle, "Can we get file handle?");
+
+  const accessHandle = await fileHandle.createSyncAccessHandle();
+  Assert.ok(!!accessHandle, "Can we create sync access handle?");
+
+  const buffer = new ArrayBuffer(
+    shrinkedStorageSizeKB * 1024 - defaultDatabaseSize
+  );
+  Assert.ok(!!buffer, "Can we create array buffer?");
+
+  const written = accessHandle.write(buffer);
+  Assert.equal(written, buffer.byteLength, "Can we write entire buffer?");
+
+  // Try to write one more byte.
+  const fileHandle2 = await root.getFileHandle("test2.txt", allowCreate);
+  Assert.ok(!!fileHandle2, "Can we get file handle?");
+
+  const accessHandle2 = await fileHandle2.createSyncAccessHandle();
+  Assert.ok(!!accessHandle2, "Can we create sync access handle?");
+
+  const buffer2 = new ArrayBuffer(1);
+  Assert.ok(!!buffer2, "Can we create array buffer?");
+
+  const written2 = accessHandle2.write(buffer2);
+  Assert.equal(written2, 0, "Can we write beyond the limit?");
+
+  await accessHandle.close();
+  await accessHandle2.close();
+
+  await Utils.restoreStorageSize();
+};
+
+for (const [key, value] of Object.entries(exported_symbols)) {
+  Object.defineProperty(value, "name", {
+    value: key,
+    writable: false,
+  });
+}
diff --git a/dom/fs/test/common/test_writableFileStream.js b/dom/fs/test/common/test_writableFileStream.js
new file mode 100644
index 0000000000..016c53bf3b
--- /dev/null
+++ b/dom/fs/test/common/test_writableFileStream.js
@@ -0,0 +1,153 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+const allowCreate = { create: true };
+
+exported_symbols.test0 = async function () {
+  let root = await navigator.storage.getDirectory();
+  Assert.ok(!!root, "Can we access the root directory?");
+
+  const testFile = await root.getFileHandle("test.txt", allowCreate);
+  Assert.ok(!!testFile, "Can't access existing file");
+  let writable = await testFile.createWritable();
+  Assert.ok(!!writable, "Can't create WritableFileStream to existing file");
+
+  // Write a sentence to the end of the file.
+  const encoder = new TextEncoder();
+  const writeBuffer = encoder.encode("Thank you for reading this.");
+  try {
+    dump("Trying to write...\n");
+    await writable.write(writeBuffer);
+    dump("closing...\n");
+    await writable.close();
+  } catch (e) {
+    Assert.ok(false, "Couldn't write to WritableFileStream: " + e);
+  }
+
+  // Read it back
+  // Get size of the file.
+  let file = await testFile.getFile();
+  Assert.ok(
+    !!file,
+    "Can't create File to file written with WritableFileStream"
+  );
+  let fileSize = file.size;
+  Assert.ok(fileSize == writeBuffer.byteLength);
+};
+
+exported_symbols.quotaTest = async function () {
+  const shrinkedStorageSizeKB = 5 * 1024;
+  const defaultDatabaseSize = 491547;
+
+  // Shrink storage size to 5MB.
+  await Utils.shrinkStorageSize(shrinkedStorageSizeKB);
+
+  let root = await navigator.storage.getDirectory();
+  Assert.ok(root, "Can we access the root directory?");
+
+  // Fill entire storage.
+  const fileHandle = await root.getFileHandle("test.txt", allowCreate);
+  Assert.ok(!!fileHandle, "Can we get file handle?");
+
+  const writable = await fileHandle.createWritable();
+  Assert.ok(!!writable, "Can we create writable file stream?");
+
+  const buffer = new ArrayBuffer(
+    shrinkedStorageSizeKB * 1024 - defaultDatabaseSize
+  );
+  Assert.ok(!!buffer, "Can we create array buffer?");
+
+  const result = await writable.write(buffer);
+  Assert.equal(result, undefined, "Can we write entire buffer?");
+
+  // Try to write one more byte.
+  const fileHandle2 = await root.getFileHandle("test2.txt", allowCreate);
+  Assert.ok(!!fileHandle2, "Can we get file handle?");
+
+  const writable2 = await fileHandle2.createWritable();
+  Assert.ok(!!writable2, "Can we create writable file stream?");
+
+  const buffer2 = new ArrayBuffer(1);
+  Assert.ok(!!buffer2, "Can we create array buffer?");
+
+  try {
+    await writable2.write(buffer2);
+    Assert.ok(false, "Should have thrown");
+  } catch (ex) {
+    Assert.ok(true, "Did throw");
+    Assert.ok(DOMException.isInstance(ex), "Threw DOMException");
+    Assert.equal(ex.name, "QuotaExceededError", "Threw right DOMException");
+  }
+
+  await writable.close();
+  // writable2 is already closed because of the failed write above
+
+  await Utils.restoreStorageSize();
+};
+
+exported_symbols.bug1823445 = async function () {
+  const root = await navigator.storage.getDirectory();
+  const testFileName = "test1823445.txt";
+  let handle = await root.getFileHandle(testFileName, allowCreate);
+  let writable = await handle.createWritable();
+  await writable.write("abcdefghijklmnop");
+  await writable.close();
+
+  handle = await root.getFileHandle(testFileName);
+  writable = await handle.createWritable({ keepExistingData: false });
+  await writable.write("12345");
+  await writable.close();
+
+  handle = await root.getFileHandle(testFileName);
+  const file = await handle.getFile();
+  const text = await file.text();
+  Assert.equal(text, "12345");
+};
+
+exported_symbols.bug1824993 = async function () {
+  const root = await navigator.storage.getDirectory();
+  const testFileName = "test1824993.txt";
+  const handle = await root.getFileHandle(testFileName, allowCreate);
+  {
+    const writable = await handle.createWritable();
+    await writable.write("test");
+
+    {
+      const file = await handle.getFile();
+      const contents = await file.text();
+      Assert.equal(contents, "");
+    }
+
+    await writable.abort();
+  }
+
+  const file = await handle.getFile();
+  const contents = await file.text();
+  Assert.equal(contents, "");
+};
+
+exported_symbols.bug1825018 = async function () {
+  const root = await navigator.storage.getDirectory();
+  const testFileName = "test1825018.txt";
+  const handle = await root.getFileHandle(testFileName, allowCreate);
+  const writable = await handle.createWritable();
+  try {
+    await writable.write({ type: "truncate" });
+  } catch (e) {
+    // Called write without size throws an error as expected
+  }
+
+  try {
+    await writable.abort();
+    await root.removeEntry(testFileName);
+  } catch (e) {
+    Assert.ok(false, e.message);
+  }
+};
+
+for (const [key, value] of Object.entries(exported_symbols)) {
+  Object.defineProperty(value, "name", {
+    value: key,
+    writable: false,
+  });
+}
diff --git a/dom/fs/test/common/xpcshell.toml b/dom/fs/test/common/xpcshell.toml
new file mode 100644
index 0000000000..9f086b65fe
--- /dev/null
+++ b/dom/fs/test/common/xpcshell.toml
@@ -0,0 +1,10 @@
+[DEFAULT]
+support-files = [
+  "nsresult.js",
+  "test_basics.js",
+  "test_fileSystemDirectoryHandle.js",
+  "test_writableFileStream.js",
+]
+
+["dummy.js"]
+skip-if = ["true"]
diff --git a/dom/fs/test/crashtests/1798773.html b/dom/fs/test/crashtests/1798773.html
new file mode 100644
index 0000000000..893dfcfc59
--- /dev/null
+++ b/dom/fs/test/crashtests/1798773.html
@@ -0,0 +1,19 @@
+<script id="worker1" type="javascript/worker">
+self.onmessage = async function () {
+  const xhr = new XMLHttpRequest()
+  self.onerror = () => {
+    xhr.open("POST", "FOOBAR", false)
+    xhr.send()
+  }
+  self.reportError(undefined)
+  self.dir = await self.navigator.storage.getDirectory()
+}
+</script>
+<script>
+window.addEventListener('load', async () => {
+  const blob = new Blob([document.querySelector('#worker1').textContent], { type: "text/javascript" })
+  let worker = new Worker(window.URL.createObjectURL(blob))
+  worker.postMessage([], [])
+  setTimeout(() => {window.location.reload(true)})
+})
+</script>
diff --git a/dom/fs/test/crashtests/1800470.html b/dom/fs/test/crashtests/1800470.html
new file mode 100644
index 0000000000..a7d5dfa8bb
--- /dev/null
+++ b/dom/fs/test/crashtests/1800470.html
@@ -0,0 +1,28 @@
+<!DOCTYPE html>
+<html class="reftest-wait">
+<head>
+  <script id="worker1" type="javascript/worker">
+    self.onmessage = async function (e) {
+      const directory = await navigator.storage.getDirectory();
+      const file = await directory.getFileHandle("500014c3-f683-4551-bb26-08025c9be332", {
+        create: true,
+      });
+      const stream = await file.createWritable({});
+      const regex = new RegExp(".*");
+      await stream.abort(regex);
+      self.postMessage("done");
+      self.close();
+    }
+  </script>
+  <script>
+    var worker;
+    document.addEventListener('DOMContentLoaded', () => {
+      const buffer = new ArrayBuffer(1);
+      const blob = new Blob([document.querySelector('#worker1').textContent], { type: 'text/javascript' });
+      worker = new Worker(window.URL.createObjectURL(blob));
+      worker.postMessage([buffer], [buffer]);
+      worker.onmessage = function() {document.documentElement.removeAttribute("class"); }
+    });
+  </script>
+</head>
+</html>
diff --git a/dom/fs/test/crashtests/1809759.html b/dom/fs/test/crashtests/1809759.html
new file mode 100644
index 0000000000..b9df8de02f
--- /dev/null
+++ b/dom/fs/test/crashtests/1809759.html
@@ -0,0 +1,10 @@
+<script>
+document.addEventListener('DOMContentLoaded', async () => {
+  document.location.search = '?'
+  let a = self.navigator.storage
+  let xhr = new XMLHttpRequest()
+  xhr.open('POST', 'FOOBAR', false)
+  xhr.send()
+  await a.getDirectory()
+})
+</script>
diff --git a/dom/fs/test/crashtests/1816710.html b/dom/fs/test/crashtests/1816710.html
new file mode 100644
index 0000000000..f7641e009d
--- /dev/null
+++ b/dom/fs/test/crashtests/1816710.html
@@ -0,0 +1,8 @@
+<script>
+  window.addEventListener('load', async () => {
+    const dir = await navigator.storage.getDirectory();
+    const file = await dir.getFileHandle('555b8afb-96ac-4fe3-8cec', { create: true });
+    const writable = await file.createWritable({});
+    setTimeout('self.close()', 2000)
+  })
+</script>
diff --git a/dom/fs/test/crashtests/1841702.html b/dom/fs/test/crashtests/1841702.html
new file mode 100644
index 0000000000..0509972ae8
--- /dev/null
+++ b/dom/fs/test/crashtests/1841702.html
@@ -0,0 +1,16 @@
+<script id="worker1" type="javascript/worker">
+self.onmessage = async function(e) {
+    let a = await e.data[0].getFileHandle("c21deba4-fb73-4407-94f8-2e3782bf3f23", {"create": true})
+    self.close()
+    await a.createWritable({})
+}
+</script>
+
+<script>
+window.addEventListener("load", async () => {
+    let a = await self.clientInformation.storage.getDirectory()
+    const blob = new Blob([document.querySelector('#worker1').textContent], { type: "text/javascript" })
+    let worker = new Worker(window.URL.createObjectURL(blob))
+    worker.postMessage([a], [])
+})
+</script>
diff --git a/dom/fs/test/crashtests/1844619.html b/dom/fs/test/crashtests/1844619.html
new file mode 100644
index 0000000000..43a85e94d9
--- /dev/null
+++ b/dom/fs/test/crashtests/1844619.html
@@ -0,0 +1,11 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <script>
+      window.addEventListener('load', async () => {
+        await navigator.serviceWorker.register('sw1844619.js?1619678955', {})
+        await navigator.serviceWorker.register('sw1844619.js?4246054133', {})
+      })
+    </script>
+</head>
+</html>
diff --git a/dom/fs/test/crashtests/1858820.html b/dom/fs/test/crashtests/1858820.html
new file mode 100644
index 0000000000..ad758b96e0
--- /dev/null
+++ b/dom/fs/test/crashtests/1858820.html
@@ -0,0 +1,19 @@
+<!DOCTYPE html>
+<html class="reftest-wait">
+<head>
+  <script>
+    window.addEventListener("load", async () => {
+      let a = document.createElement("iframe")
+      document.documentElement.appendChild(a)
+      let b = await a.contentWindow.clientInformation.storage.getDirectory()
+      let c = await b.getFileHandle("80e2d2c3-0712-4ccd-94b5-e2dd1732ea09", {"create": true})
+      let d = await c.createWritable({ })
+      setTimeout(async () => {
+        document.documentElement.removeAttribute("class");
+        await d.truncate(1);
+      }, 1000)
+      document.replaceChildren(document.documentElement, document.documentElement)
+    })
+  </script>
+</head>
+</html>
diff --git a/dom/fs/test/crashtests/crashtests.list b/dom/fs/test/crashtests/crashtests.list
new file mode 100644
index 0000000000..a083cb80b2
--- /dev/null
+++ b/dom/fs/test/crashtests/crashtests.list
@@ -0,0 +1,10 @@
+# StorageManager isn't enabled on Android
+defaults skip-if(Android) pref(dom.fs.enabled,true) pref(dom.fs.writable_file_stream.enabled,true)
+
+load 1798773.html
+load 1800470.html
+load 1809759.html
+load 1816710.html
+load 1841702.html
+HTTP load 1844619.html
+HTTP load 1858820.html
diff --git a/dom/fs/test/crashtests/sw1844619.js b/dom/fs/test/crashtests/sw1844619.js
new file mode 100644
index 0000000000..dd221844f2
--- /dev/null
+++ b/dom/fs/test/crashtests/sw1844619.js
@@ -0,0 +1,21 @@
+async function timeout (cmd) {
+  const timer = new Promise((resolve, reject) => {
+    const id = setTimeout(() => {
+      clearTimeout(id)
+      reject(new Error('Promise timed out!'))
+    }, 750)
+  })
+  return Promise.race([cmd, timer])
+}
+
+(async () => {
+  const root = await navigator.storage.getDirectory()
+  const blob = new Blob(['A'])
+  const sub = await root.getDirectoryHandle('a', { 'create': true })
+  const file = await root.getFileHandle('b', { 'create': true })
+  await file.move(sub)
+  const stream = await file.createWritable({})
+  await stream.write(blob)
+  const sub2 = await root.getDirectoryHandle('a', {})
+  await sub2.move(root, 'X')
+})()
diff --git a/dom/fs/test/gtest/FileSystemMocks.cpp b/dom/fs/test/gtest/FileSystemMocks.cpp
new file mode 100644
index 0000000000..1ad8e77c56
--- /dev/null
+++ b/dom/fs/test/gtest/FileSystemMocks.cpp
@@ -0,0 +1,94 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "FileSystemMocks.h"
+
+#include <string>
+
+#include "ErrorList.h"
+#include "gtest/gtest-assertion-result.h"
+#include "js/RootingAPI.h"
+#include "jsapi.h"
+#include "mozilla/dom/FileSystemManager.h"
+#include "nsContentUtils.h"
+#include "nsISupports.h"
+
+namespace mozilla::dom::fs::test {
+
+nsIGlobalObject* GetGlobal() {
+  AutoJSAPI jsapi;
+  DebugOnly<bool> ok = jsapi.Init(xpc::PrivilegedJunkScope());
+  MOZ_ASSERT(ok);
+
+  JSContext* cx = jsapi.cx();
+  mozilla::dom::GlobalObject globalObject(cx, JS::CurrentGlobalOrNull(cx));
+  nsCOMPtr<nsIGlobalObject> global =
+      do_QueryInterface(globalObject.GetAsSupports());
+  MOZ_ASSERT(global);
+
+  return global.get();
+}
+
+nsresult GetAsString(const RefPtr<Promise>& aPromise, nsAString& aString) {
+  AutoJSAPI jsapi;
+  DebugOnly<bool> ok = jsapi.Init(xpc::PrivilegedJunkScope());
+  MOZ_ASSERT(ok);
+
+  JSContext* cx = jsapi.cx();
+
+  JS::Rooted<JSObject*> promiseObj(cx, aPromise->PromiseObj());
+  JS::Rooted<JS::Value> vp(cx, JS::GetPromiseResult(promiseObj));
+
+  switch (aPromise->State()) {
+    case Promise::PromiseState::Pending: {
+      return NS_ERROR_DOM_INVALID_STATE_ERR;
+    }
+
+    case Promise::PromiseState::Resolved: {
+      if (nsContentUtils::StringifyJSON(cx, vp, aString,
+                                        UndefinedIsNullStringLiteral)) {
+        return NS_OK;
+      }
+
+      return NS_ERROR_UNEXPECTED;
+    }
+
+    case Promise::PromiseState::Rejected: {
+      if (vp.isInt32()) {
+        int32_t errorCode = vp.toInt32();
+        aString.AppendInt(errorCode);
+
+        return NS_OK;
+      }
+
+      if (!vp.isObject()) {
+        return NS_ERROR_UNEXPECTED;
+      }
+
+      RefPtr<Exception> exception;
+      UNWRAP_OBJECT(Exception, &vp, exception);
+      if (!exception) {
+        return NS_ERROR_UNEXPECTED;
+      }
+
+      aString.Append(NS_ConvertUTF8toUTF16(
+          GetStaticErrorName(static_cast<nsresult>(exception->Result()))));
+
+      return NS_OK;
+    }
+
+    default:
+      break;
+  }
+
+  return NS_ERROR_FAILURE;
+}
+
+mozilla::ipc::PrincipalInfo GetPrincipalInfo() {
+  return mozilla::ipc::PrincipalInfo{mozilla::ipc::SystemPrincipalInfo{}};
+}
+
+}  // namespace mozilla::dom::fs::test
diff --git a/dom/fs/test/gtest/FileSystemMocks.h b/dom/fs/test/gtest/FileSystemMocks.h
new file mode 100644
index 0000000000..1926b2e86a
--- /dev/null
+++ b/dom/fs/test/gtest/FileSystemMocks.h
@@ -0,0 +1,340 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef DOM_FS_TEST_GTEST_FILESYSTEMMOCKS_H_
+#define DOM_FS_TEST_GTEST_FILESYSTEMMOCKS_H_
+
+#include <memory>  // We don't have a mozilla shared pointer for pod types
+
+#include "TestHelpers.h"
+#include "fs/FileSystemChildFactory.h"
+#include "fs/FileSystemRequestHandler.h"
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "js/Promise.h"
+#include "js/RootingAPI.h"
+#include "jsapi.h"
+#include "mozilla/ErrorResult.h"
+#include "mozilla/ScopeExit.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/dom/BindingDeclarations.h"
+#include "mozilla/dom/BindingUtils.h"
+#include "mozilla/dom/DOMException.h"
+#include "mozilla/dom/DOMExceptionBinding.h"
+#include "mozilla/dom/FileSystemManagerChild.h"
+#include "mozilla/dom/Promise.h"
+#include "mozilla/dom/PromiseNativeHandler.h"
+#include "mozilla/dom/ScriptSettings.h"
+#include "mozilla/ipc/PBackgroundSharedTypes.h"
+#include "nsIGlobalObject.h"
+#include "nsISupports.h"
+#include "nsISupportsImpl.h"
+#include "nsITimer.h"
+
+namespace mozilla::dom::fs {
+
+inline std::ostream& operator<<(std::ostream& aOut,
+                                const FileSystemEntryMetadata& aMetadata) {
+  return aOut;
+}
+
+namespace test {
+
+nsIGlobalObject* GetGlobal();
+
+nsresult GetAsString(const RefPtr<Promise>& aPromise, nsAString& aString);
+
+mozilla::ipc::PrincipalInfo GetPrincipalInfo();
+
+class MockFileSystemRequestHandler : public FileSystemRequestHandler {
+ public:
+  MOCK_METHOD(void, GetRootHandle,
+              (RefPtr<FileSystemManager> aManager, RefPtr<Promise> aPromise,
+               ErrorResult& aError),
+              (override));
+
+  MOCK_METHOD(void, GetDirectoryHandle,
+              (RefPtr<FileSystemManager> & aManager,
+               const FileSystemChildMetadata& aDirectory, bool aCreate,
+               RefPtr<Promise> aPromise, ErrorResult& aError),
+              (override));
+
+  MOCK_METHOD(void, GetFileHandle,
+              (RefPtr<FileSystemManager> & aManager,
+               const FileSystemChildMetadata& aFile, bool aCreate,
+               RefPtr<Promise> aPromise, ErrorResult& aError),
+              (override));
+
+  MOCK_METHOD(void, GetFile,
+              (RefPtr<FileSystemManager> & aManager,
+               const FileSystemEntryMetadata& aFile, RefPtr<Promise> aPromise,
+               ErrorResult& aError),
+              (override));
+
+  MOCK_METHOD(void, GetEntries,
+              (RefPtr<FileSystemManager> & aManager, const EntryId& aDirectory,
+               PageNumber aPage, RefPtr<Promise> aPromise,
+               RefPtr<FileSystemEntryMetadataArray>& aSink,
+               ErrorResult& aError),
+              (override));
+
+  MOCK_METHOD(void, RemoveEntry,
+              (RefPtr<FileSystemManager> & aManager,
+               const FileSystemChildMetadata& aEntry, bool aRecursive,
+               RefPtr<Promise> aPromise, ErrorResult& aError),
+              (override));
+
+  MOCK_METHOD(void, MoveEntry,
+              (RefPtr<FileSystemManager> & aManager, FileSystemHandle* aHandle,
+               FileSystemEntryMetadata* const aEntry,
+               const FileSystemChildMetadata& aNewEntry,
+               RefPtr<Promise> aPromise, ErrorResult& aError),
+              (override));
+
+  MOCK_METHOD(void, RenameEntry,
+              (RefPtr<FileSystemManager> & aManager, FileSystemHandle* aHandle,
+               FileSystemEntryMetadata* const aEntry, const Name& aName,
+               RefPtr<Promise> aPromise, ErrorResult& aError),
+              (override));
+
+  MOCK_METHOD(void, Resolve,
+              (RefPtr<FileSystemManager> & aManager,
+               const FileSystemEntryPair& aEndpoints, RefPtr<Promise> aPromise,
+               ErrorResult& aError),
+              (override));
+};
+
+class WaitablePromiseListener {
+ public:
+  NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING
+
+  virtual void ClearDone() = 0;
+
+  virtual bool IsDone() const = 0;
+
+  virtual PromiseNativeHandler* AsHandler() = 0;
+
+ protected:
+  virtual ~WaitablePromiseListener() = default;
+};
+
+template <class SuccessHandler, class ErrorHandler,
+          uint32_t MilliSeconds = 2000u>
+class TestPromiseListener : public PromiseNativeHandler,
+                            public WaitablePromiseListener {
+ public:
+  TestPromiseListener()
+      : mIsDone(std::make_shared<bool>(false)), mOnSuccess(), mOnError() {
+    ClearDone();
+  }
+
+  // nsISupports implementation
+
+  NS_IMETHODIMP QueryInterface(REFNSIID aIID, void** aInstancePtr) override {
+    nsresult rv = NS_ERROR_UNEXPECTED;
+    NS_INTERFACE_TABLE0(TestPromiseListener)
+
+    return rv;
+  }
+
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(TestPromiseListener, override)
+
+  // PromiseNativeHandler implementation
+
+  void ResolvedCallback(JSContext* aCx, JS::Handle<JS::Value> aValue,
+                        ErrorResult& aError) override {
+    mozilla::ScopeExit flagAsDone([isDone = mIsDone, timer = mTimer] {
+      timer->Cancel();
+      *isDone = true;
+    });
+
+    mOnSuccess();
+  }
+
+  void RejectedCallback(JSContext* aCx, JS::Handle<JS::Value> aValue,
+                        ErrorResult& aError) override {
+    mozilla::ScopeExit flagAsDone([isDone = mIsDone, timer = mTimer] {
+      timer->Cancel();
+      *isDone = true;
+    });
+
+    if (aValue.isInt32()) {
+      mOnError(static_cast<nsresult>(aValue.toInt32()));
+      return;
+    }
+
+    ASSERT_TRUE(aValue.isObject());
+    JS::Rooted<JSObject*> exceptionObject(aCx, &aValue.toObject());
+
+    RefPtr<Exception> exception;
+    UNWRAP_OBJECT(Exception, exceptionObject, exception);
+    if (exception) {
+      mOnError(static_cast<nsresult>(exception->Result()));
+      return;
+    }
+  }
+
+  // WaitablePromiseListener implementation
+
+  void ClearDone() override {
+    *mIsDone = false;
+    if (mTimer) {
+      mTimer->Cancel();
+    }
+    auto timerCallback = [isDone = mIsDone](nsITimer* aTimer) {
+      *isDone = true;
+      FAIL() << "Timed out!";
+    };
+    const char* timerName = "fs::TestPromiseListener::ClearDone";
+    auto res = NS_NewTimerWithCallback(timerCallback, MilliSeconds,
+                                       nsITimer::TYPE_ONE_SHOT, timerName);
+    if (res.isOk()) {
+      mTimer = res.unwrap();
+    }
+  }
+
+  bool IsDone() const override { return *mIsDone; }
+
+  PromiseNativeHandler* AsHandler() override { return this; }
+
+  SuccessHandler& GetSuccessHandler() { return mOnSuccess; }
+
+  SuccessHandler& GetErrorHandler() { return mOnError; }
+
+ protected:
+  virtual ~TestPromiseListener() = default;
+
+  std::shared_ptr<bool> mIsDone;  // We pass this to a callback
+
+  nsCOMPtr<nsITimer> mTimer;
+
+  SuccessHandler mOnSuccess;
+
+  ErrorHandler mOnError;
+};
+
+class TestFileSystemManagerChild : public FileSystemManagerChild {
+ public:
+  MOCK_METHOD(void, SendGetRootHandle,
+              (mozilla::ipc::ResolveCallback<FileSystemGetHandleResponse> &&
+                   aResolve,
+               mozilla::ipc::RejectCallback&& aReject),
+              (override));
+
+  MOCK_METHOD(
+      void, SendGetDirectoryHandle,
+      (const FileSystemGetHandleRequest& request,
+       mozilla::ipc::ResolveCallback<FileSystemGetHandleResponse>&& aResolve,
+       mozilla::ipc::RejectCallback&& aReject),
+      (override));
+
+  MOCK_METHOD(
+      void, SendGetFileHandle,
+      (const FileSystemGetHandleRequest& request,
+       mozilla::ipc::ResolveCallback<FileSystemGetHandleResponse>&& aResolve,
+       mozilla::ipc::RejectCallback&& aReject),
+      (override));
+
+  MOCK_METHOD(
+      void, SendGetAccessHandle,
+      (const FileSystemGetAccessHandleRequest& request,
+       mozilla::ipc::ResolveCallback<FileSystemGetAccessHandleResponse>&&
+           aResolve,
+       mozilla::ipc::RejectCallback&& aReject),
+      (override));
+
+  MOCK_METHOD(
+      void, SendGetWritable,
+      (const FileSystemGetWritableRequest& request,
+       mozilla::ipc::ResolveCallback<FileSystemGetWritableFileStreamResponse>&&
+           aResolve,
+       mozilla::ipc::RejectCallback&& aReject),
+      (override));
+
+  MOCK_METHOD(
+      void, SendGetFile,
+      (const FileSystemGetFileRequest& request,
+       mozilla::ipc::ResolveCallback<FileSystemGetFileResponse>&& aResolve,
+       mozilla::ipc::RejectCallback&& aReject),
+      (override));
+
+  MOCK_METHOD(
+      void, SendResolve,
+      (const FileSystemResolveRequest& request,
+       mozilla::ipc::ResolveCallback<FileSystemResolveResponse>&& aResolve,
+       mozilla::ipc::RejectCallback&& aReject),
+      (override));
+
+  MOCK_METHOD(
+      void, SendGetEntries,
+      (const FileSystemGetEntriesRequest& request,
+       mozilla::ipc::ResolveCallback<FileSystemGetEntriesResponse>&& aResolve,
+       mozilla::ipc::RejectCallback&& aReject),
+      (override));
+
+  MOCK_METHOD(
+      void, SendRemoveEntry,
+      (const FileSystemRemoveEntryRequest& request,
+       mozilla::ipc::ResolveCallback<FileSystemRemoveEntryResponse>&& aResolve,
+       mozilla::ipc::RejectCallback&& aReject),
+      (override));
+
+  MOCK_METHOD(void, Shutdown, (), (override));
+
+ protected:
+  virtual ~TestFileSystemManagerChild() = default;
+};
+
+class TestFileSystemChildFactory final : public FileSystemChildFactory {
+ public:
+  explicit TestFileSystemChildFactory(TestFileSystemManagerChild* aChild)
+      : mChild(aChild) {}
+
+  already_AddRefed<FileSystemManagerChild> Create() const override {
+    return RefPtr<TestFileSystemManagerChild>(mChild).forget();
+  }
+
+  ~TestFileSystemChildFactory() = default;
+
+ private:
+  TestFileSystemManagerChild* mChild;
+};
+
+struct MockExpectMe {
+  MOCK_METHOD0(InvokeMe, void());
+
+  template <class... Args>
+  void operator()(Args...) {
+    InvokeMe();
+  }
+};
+
+template <nsresult Expected>
+struct NSErrorMatcher {
+  void operator()(nsresult aErr) { ASSERT_NSEQ(Expected, aErr); }
+};
+
+struct FailOnCall {
+  template <class... Args>
+  void operator()(Args...) {
+    FAIL();
+  }
+};
+
+}  // namespace test
+}  // namespace mozilla::dom::fs
+
+#define MOCK_PROMISE_LISTENER(name, ...) \
+  using name = mozilla::dom::fs::test::TestPromiseListener<__VA_ARGS__>;
+
+MOCK_PROMISE_LISTENER(
+    ExpectNotImplemented, mozilla::dom::fs::test::FailOnCall,
+    mozilla::dom::fs::test::NSErrorMatcher<NS_ERROR_NOT_IMPLEMENTED>);
+
+MOCK_PROMISE_LISTENER(ExpectResolveCalled, mozilla::dom::fs::test::MockExpectMe,
+                      mozilla::dom::fs::test::FailOnCall);
+
+#endif  // DOM_FS_TEST_GTEST_FILESYSTEMMOCKS_H_
diff --git a/dom/fs/test/gtest/TestHelpers.cpp b/dom/fs/test/gtest/TestHelpers.cpp
new file mode 100644
index 0000000000..b028530f19
--- /dev/null
+++ b/dom/fs/test/gtest/TestHelpers.cpp
@@ -0,0 +1,61 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "TestHelpers.h"
+
+#include "gtest/gtest.h"
+#include "mozilla/dom/quota/CommonMetadata.h"
+#include "nsString.h"
+
+namespace testing::internal {
+
+GTEST_API_ ::testing::AssertionResult CmpHelperSTREQ(const char* s1_expression,
+                                                     const char* s2_expression,
+                                                     const nsAString& s1,
+                                                     const nsAString& s2) {
+  if (s1.Equals(s2)) {
+    return ::testing::AssertionSuccess();
+  }
+
+  return ::testing::internal::EqFailure(
+      s1_expression, s2_expression,
+      std::string(NS_ConvertUTF16toUTF8(s1).get()),
+      std::string(NS_ConvertUTF16toUTF8(s2).get()),
+      /* ignore case */ false);
+}
+
+GTEST_API_ ::testing::AssertionResult CmpHelperSTREQ(const char* s1_expression,
+                                                     const char* s2_expression,
+                                                     const nsACString& s1,
+                                                     const nsACString& s2) {
+  if (s1.Equals(s2)) {
+    return ::testing::AssertionSuccess();
+  }
+
+  return ::testing::internal::EqFailure(s1_expression, s2_expression,
+                                        std::string(s1), std::string(s2),
+                                        /* ignore case */ false);
+}
+
+}  // namespace testing::internal
+
+namespace mozilla::dom::fs::test {
+
+quota::OriginMetadata GetTestOriginMetadata() {
+  return quota::OriginMetadata{""_ns,
+                               "example.com"_ns,
+                               "http://example.com"_ns,
+                               "http://example.com"_ns,
+                               /* aIsPrivate */ false,
+                               quota::PERSISTENCE_TYPE_DEFAULT};
+}
+
+const Origin& GetTestOrigin() {
+  static const Origin origin = "http://example.com"_ns;
+  return origin;
+}
+
+}  // namespace mozilla::dom::fs::test
diff --git a/dom/fs/test/gtest/TestHelpers.h b/dom/fs/test/gtest/TestHelpers.h
new file mode 100644
index 0000000000..bfbcb9840c
--- /dev/null
+++ b/dom/fs/test/gtest/TestHelpers.h
@@ -0,0 +1,69 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef DOM_FS_TEST_GTEST_TESTHELPERS_H_
+#define DOM_FS_TEST_GTEST_TESTHELPERS_H_
+
+#include "ErrorList.h"
+#include "gtest/gtest.h"
+#include "mozilla/ErrorNames.h"
+#include "mozilla/dom/FileSystemTypes.h"
+#include "mozilla/dom/quota/QuotaCommon.h"
+
+namespace testing::internal {
+
+GTEST_API_ ::testing::AssertionResult CmpHelperSTREQ(const char* s1_expression,
+                                                     const char* s2_expression,
+                                                     const nsAString& s1,
+                                                     const nsAString& s2);
+
+GTEST_API_ ::testing::AssertionResult CmpHelperSTREQ(const char* s1_expression,
+                                                     const char* s2_expression,
+                                                     const nsACString& s1,
+                                                     const nsACString& s2);
+
+}  // namespace testing::internal
+
+#define ASSERT_NSEQ(lhs, rhs) \
+  ASSERT_STREQ(GetStaticErrorName((lhs)), GetStaticErrorName((rhs)))
+
+#define TEST_TRY_UNWRAP_META(tempVar, target, expr)                \
+  auto MOZ_REMOVE_PAREN(tempVar) = (expr);                         \
+  ASSERT_TRUE(MOZ_REMOVE_PAREN(tempVar).isOk())                    \
+  << GetStaticErrorName(                                           \
+      mozilla::ToNSResult(MOZ_REMOVE_PAREN(tempVar).unwrapErr())); \
+  MOZ_REMOVE_PAREN(target) = MOZ_REMOVE_PAREN(tempVar).unwrap();
+
+#define TEST_TRY_UNWRAP_ERR_META(tempVar, target, expr) \
+  auto MOZ_REMOVE_PAREN(tempVar) = (expr);              \
+  ASSERT_TRUE(MOZ_REMOVE_PAREN(tempVar).isErr());       \
+  MOZ_REMOVE_PAREN(target) =                            \
+      mozilla::ToNSResult(MOZ_REMOVE_PAREN(tempVar).unwrapErr());
+
+#define TEST_TRY_UNWRAP(target, expr) \
+  TEST_TRY_UNWRAP_META(MOZ_UNIQUE_VAR(testVar), target, expr)
+
+#define TEST_TRY_UNWRAP_ERR(target, expr) \
+  TEST_TRY_UNWRAP_ERR_META(MOZ_UNIQUE_VAR(testVar), target, expr)
+
+namespace mozilla::dom {
+
+namespace quota {
+
+struct OriginMetadata;
+
+}  // namespace quota
+
+namespace fs::test {
+
+quota::OriginMetadata GetTestOriginMetadata();
+
+const Origin& GetTestOrigin();
+
+}  // namespace fs::test
+}  // namespace mozilla::dom
+
+#endif  // DOM_FS_TEST_GTEST_TESTHELPERS_H_
diff --git a/dom/fs/test/gtest/api/TestFileSystemDirectoryHandle.cpp b/dom/fs/test/gtest/api/TestFileSystemDirectoryHandle.cpp
new file mode 100644
index 0000000000..6aadd226e9
--- /dev/null
+++ b/dom/fs/test/gtest/api/TestFileSystemDirectoryHandle.cpp
@@ -0,0 +1,234 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "FileSystemMocks.h"
+#include "gtest/gtest.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/dom/FileSystemDirectoryHandle.h"
+#include "mozilla/dom/FileSystemDirectoryHandleBinding.h"
+#include "mozilla/dom/FileSystemHandle.h"
+#include "mozilla/dom/FileSystemHandleBinding.h"
+#include "mozilla/dom/FileSystemManager.h"
+#include "mozilla/dom/StorageManager.h"
+#include "nsIGlobalObject.h"
+
+using ::testing::_;
+
+namespace mozilla::dom::fs::test {
+
+class TestFileSystemDirectoryHandle : public ::testing::Test {
+ protected:
+  void SetUp() override {
+    // TODO: Fix the test to not depend on CreateFileSystemManagerParent
+    // failure because of the pref set to false.
+    nsCOMPtr<nsIPrefBranch> prefs = do_GetService(NS_PREFSERVICE_CONTRACTID);
+    prefs->SetBoolPref("dom.fs.enabled", false);
+
+    mRequestHandler = MakeUnique<MockFileSystemRequestHandler>();
+    mMetadata = FileSystemEntryMetadata("dir"_ns, u"Directory"_ns,
+                                        /* directory */ true);
+    mName = u"testDir"_ns;
+    mManager = MakeAndAddRef<FileSystemManager>(mGlobal, nullptr);
+  }
+
+  void TearDown() override {
+    nsCOMPtr<nsIPrefBranch> prefs = do_GetService(NS_PREFSERVICE_CONTRACTID);
+    prefs->SetBoolPref("dom.fs.enabled", true);
+
+    if (!mManager->IsShutdown()) {
+      mManager->Shutdown();
+    }
+  }
+
+  nsIGlobalObject* mGlobal = GetGlobal();
+  const IterableIteratorBase::IteratorType mIteratorType =
+      IterableIteratorBase::IteratorType::Keys;
+  UniquePtr<MockFileSystemRequestHandler> mRequestHandler;
+  FileSystemEntryMetadata mMetadata;
+  nsString mName;
+  RefPtr<FileSystemManager> mManager;
+};
+
+TEST_F(TestFileSystemDirectoryHandle, constructDirectoryHandleRefPointer) {
+  RefPtr<FileSystemDirectoryHandle> dirHandle =
+      MakeAndAddRef<FileSystemDirectoryHandle>(mGlobal, mManager, mMetadata);
+
+  ASSERT_TRUE(dirHandle);
+}
+
+TEST_F(TestFileSystemDirectoryHandle, initIterator) {
+  RefPtr<FileSystemDirectoryHandle> dirHandle =
+      MakeAndAddRef<FileSystemDirectoryHandle>(mGlobal, mManager, mMetadata,
+                                               mRequestHandler.release());
+
+  ASSERT_TRUE(dirHandle);
+
+  RefPtr<FileSystemDirectoryHandle::iterator_t> iterator =
+      new FileSystemDirectoryHandle::iterator_t(dirHandle.get(), mIteratorType);
+  IgnoredErrorResult rv;
+  dirHandle->InitAsyncIteratorData(iterator->Data(), mIteratorType, rv);
+  ASSERT_TRUE(iterator->Data().mImpl);
+}
+
+class MockFileSystemDirectoryIteratorImpl final
+    : public FileSystemDirectoryIterator::Impl {
+ public:
+  MOCK_METHOD(already_AddRefed<Promise>, Next,
+              (nsIGlobalObject * aGlobal, RefPtr<FileSystemManager>& aManager,
+               ErrorResult& aError),
+              (override));
+};
+
+TEST_F(TestFileSystemDirectoryHandle, isNextPromiseReturned) {
+  RefPtr<FileSystemDirectoryHandle> dirHandle =
+      MakeAndAddRef<FileSystemDirectoryHandle>(mGlobal, mManager, mMetadata,
+                                               mRequestHandler.release());
+
+  ASSERT_TRUE(dirHandle);
+
+  auto mockIter = MakeRefPtr<MockFileSystemDirectoryIteratorImpl>();
+  IgnoredErrorResult error;
+  EXPECT_CALL(*mockIter, Next(_, _, _))
+      .WillOnce(::testing::Return(Promise::Create(mGlobal, error)));
+
+  RefPtr<FileSystemDirectoryHandle::iterator_t> iterator =
+      MakeAndAddRef<FileSystemDirectoryHandle::iterator_t>(dirHandle.get(),
+                                                           mIteratorType);
+  iterator->Data().mImpl = std::move(mockIter);
+
+  IgnoredErrorResult rv;
+  RefPtr<Promise> promise =
+      dirHandle->GetNextIterationResult(iterator.get(), rv);
+  ASSERT_TRUE(promise);
+}
+
+TEST_F(TestFileSystemDirectoryHandle, isHandleKindDirectory) {
+  RefPtr<FileSystemDirectoryHandle> dirHandle =
+      MakeAndAddRef<FileSystemDirectoryHandle>(mGlobal, mManager, mMetadata,
+                                               mRequestHandler.release());
+
+  ASSERT_TRUE(dirHandle);
+
+  ASSERT_EQ(FileSystemHandleKind::Directory, dirHandle->Kind());
+}
+
+TEST_F(TestFileSystemDirectoryHandle, isFileHandleReturned) {
+  EXPECT_CALL(*mRequestHandler, GetFileHandle(_, _, _, _, _))
+      .WillOnce(::testing::ReturnArg<3>());
+  RefPtr<FileSystemDirectoryHandle> dirHandle =
+      MakeAndAddRef<FileSystemDirectoryHandle>(mGlobal, mManager, mMetadata,
+                                               mRequestHandler.release());
+
+  ASSERT_TRUE(dirHandle);
+
+  FileSystemGetFileOptions options;
+  IgnoredErrorResult rv;
+  RefPtr<Promise> promise = dirHandle->GetFileHandle(mName, options, rv);
+
+  ASSERT_TRUE(rv.ErrorCodeIs(NS_OK));
+}
+
+TEST_F(TestFileSystemDirectoryHandle, doesGetFileHandleFailOnNullGlobal) {
+  mGlobal = nullptr;
+  RefPtr<FileSystemDirectoryHandle> dirHandle =
+      MakeAndAddRef<FileSystemDirectoryHandle>(mGlobal, mManager, mMetadata);
+
+  ASSERT_TRUE(dirHandle);
+
+  FileSystemGetFileOptions options;
+  IgnoredErrorResult rv;
+  RefPtr<Promise> promise = dirHandle->GetFileHandle(mName, options, rv);
+
+  ASSERT_TRUE(rv.ErrorCodeIs(NS_ERROR_UNEXPECTED));
+}
+
+TEST_F(TestFileSystemDirectoryHandle, isDirectoryHandleReturned) {
+  EXPECT_CALL(*mRequestHandler, GetDirectoryHandle(_, _, _, _, _))
+      .WillOnce(::testing::ReturnArg<3>());
+  RefPtr<FileSystemDirectoryHandle> dirHandle =
+      MakeAndAddRef<FileSystemDirectoryHandle>(mGlobal, mManager, mMetadata,
+                                               mRequestHandler.release());
+
+  ASSERT_TRUE(dirHandle);
+
+  FileSystemGetDirectoryOptions options;
+  IgnoredErrorResult rv;
+  RefPtr<Promise> promise = dirHandle->GetDirectoryHandle(mName, options, rv);
+
+  ASSERT_TRUE(rv.ErrorCodeIs(NS_OK));
+}
+
+TEST_F(TestFileSystemDirectoryHandle, doesGetDirectoryHandleFailOnNullGlobal) {
+  mGlobal = nullptr;
+  RefPtr<FileSystemDirectoryHandle> dirHandle =
+      MakeAndAddRef<FileSystemDirectoryHandle>(mGlobal, mManager, mMetadata);
+
+  ASSERT_TRUE(dirHandle);
+
+  FileSystemGetDirectoryOptions options;
+  IgnoredErrorResult rv;
+  RefPtr<Promise> promise = dirHandle->GetDirectoryHandle(mName, options, rv);
+
+  ASSERT_TRUE(rv.ErrorCodeIs(NS_ERROR_UNEXPECTED));
+}
+
+TEST_F(TestFileSystemDirectoryHandle, isRemoveEntrySuccessful) {
+  EXPECT_CALL(*mRequestHandler, RemoveEntry(_, _, _, _, _))
+      .WillOnce(::testing::ReturnArg<3>());
+  RefPtr<FileSystemDirectoryHandle> dirHandle =
+      MakeAndAddRef<FileSystemDirectoryHandle>(mGlobal, mManager, mMetadata,
+                                               mRequestHandler.release());
+
+  ASSERT_TRUE(dirHandle);
+
+  FileSystemRemoveOptions options;
+  IgnoredErrorResult rv;
+  RefPtr<Promise> promise = dirHandle->RemoveEntry(mName, options, rv);
+
+  ASSERT_TRUE(rv.ErrorCodeIs(NS_OK));
+}
+
+TEST_F(TestFileSystemDirectoryHandle, doesRemoveEntryFailOnNullGlobal) {
+  mGlobal = nullptr;
+  RefPtr<FileSystemDirectoryHandle> dirHandle =
+      MakeAndAddRef<FileSystemDirectoryHandle>(mGlobal, mManager, mMetadata);
+
+  ASSERT_TRUE(dirHandle);
+
+  FileSystemRemoveOptions options;
+  IgnoredErrorResult rv;
+  RefPtr<Promise> promise = dirHandle->RemoveEntry(mName, options, rv);
+
+  ASSERT_TRUE(rv.ErrorCodeIs(NS_ERROR_UNEXPECTED));
+}
+
+TEST_F(TestFileSystemDirectoryHandle, isResolveSuccessful) {
+  RefPtr<FileSystemDirectoryHandle> dirHandle =
+      MakeAndAddRef<FileSystemDirectoryHandle>(mGlobal, mManager, mMetadata,
+                                               mRequestHandler.release());
+
+  ASSERT_TRUE(dirHandle);
+
+  IgnoredErrorResult rv;
+  RefPtr<Promise> promise = dirHandle->Resolve(*dirHandle, rv);
+
+  ASSERT_TRUE(rv.ErrorCodeIs(NS_OK));
+}
+
+TEST_F(TestFileSystemDirectoryHandle, doesResolveFailOnNullGlobal) {
+  mGlobal = nullptr;
+  RefPtr<FileSystemDirectoryHandle> dirHandle =
+      MakeAndAddRef<FileSystemDirectoryHandle>(mGlobal, mManager, mMetadata);
+
+  ASSERT_TRUE(dirHandle);
+
+  IgnoredErrorResult rv;
+  RefPtr<Promise> promise = dirHandle->Resolve(*dirHandle, rv);
+
+  ASSERT_TRUE(rv.ErrorCodeIs(NS_ERROR_UNEXPECTED));
+}
+
+}  // namespace mozilla::dom::fs::test
diff --git a/dom/fs/test/gtest/api/TestFileSystemFileHandle.cpp b/dom/fs/test/gtest/api/TestFileSystemFileHandle.cpp
new file mode 100644
index 0000000000..263c1f2ed1
--- /dev/null
+++ b/dom/fs/test/gtest/api/TestFileSystemFileHandle.cpp
@@ -0,0 +1,144 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "FileSystemMocks.h"
+#include "fs/FileSystemChildFactory.h"
+#include "gtest/gtest.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/dom/FileSystemFileHandle.h"
+#include "mozilla/dom/FileSystemFileHandleBinding.h"
+#include "mozilla/dom/FileSystemHandle.h"
+#include "mozilla/dom/FileSystemHandleBinding.h"
+#include "mozilla/dom/FileSystemManager.h"
+#include "mozilla/dom/Promise.h"
+#include "mozilla/dom/StorageManager.h"
+#include "nsIGlobalObject.h"
+
+namespace mozilla::dom::fs::test {
+
+class TestFileSystemFileHandle : public ::testing::Test {
+ protected:
+  void SetUp() override {
+    // TODO: Fix the test to not depend on CreateFileSystemManagerParent
+    // failure because of the pref set to false.
+    nsCOMPtr<nsIPrefBranch> prefs = do_GetService(NS_PREFSERVICE_CONTRACTID);
+    prefs->SetBoolPref("dom.fs.enabled", false);
+
+    mRequestHandler = MakeUnique<MockFileSystemRequestHandler>();
+    mMetadata =
+        FileSystemEntryMetadata("file"_ns, u"File"_ns, /* directory */ false);
+    mManager = MakeAndAddRef<FileSystemManager>(mGlobal, nullptr);
+  }
+
+  void TearDown() override {
+    nsCOMPtr<nsIPrefBranch> prefs = do_GetService(NS_PREFSERVICE_CONTRACTID);
+    prefs->SetBoolPref("dom.fs.enabled", true);
+
+    if (!mManager->IsShutdown()) {
+      mManager->Shutdown();
+    }
+  }
+
+  nsIGlobalObject* mGlobal = GetGlobal();
+  UniquePtr<MockFileSystemRequestHandler> mRequestHandler;
+  FileSystemEntryMetadata mMetadata;
+  RefPtr<FileSystemManager> mManager;
+};
+
+TEST_F(TestFileSystemFileHandle, constructFileHandleRefPointer) {
+  RefPtr<FileSystemFileHandle> fileHandle = MakeAndAddRef<FileSystemFileHandle>(
+      mGlobal, mManager, mMetadata, mRequestHandler.release());
+
+  ASSERT_TRUE(fileHandle);
+}
+
+TEST_F(TestFileSystemFileHandle, isHandleKindFile) {
+  RefPtr<FileSystemFileHandle> fileHandle = MakeAndAddRef<FileSystemFileHandle>(
+      mGlobal, mManager, mMetadata, mRequestHandler.release());
+
+  ASSERT_TRUE(fileHandle);
+
+  ASSERT_EQ(FileSystemHandleKind::File, fileHandle->Kind());
+}
+
+TEST_F(TestFileSystemFileHandle, isFileReturned) {
+  RefPtr<FileSystemFileHandle> fileHandle = MakeAndAddRef<FileSystemFileHandle>(
+      mGlobal, mManager, mMetadata, mRequestHandler.release());
+
+  ASSERT_TRUE(fileHandle);
+
+  IgnoredErrorResult rv;
+  RefPtr<Promise> promise = fileHandle->GetFile(rv);
+
+  ASSERT_TRUE(rv.ErrorCodeIs(NS_OK));
+}
+
+TEST_F(TestFileSystemFileHandle, doesGetFileFailOnNullGlobal) {
+  mGlobal = nullptr;
+  RefPtr<FileSystemFileHandle> fileHandle = MakeAndAddRef<FileSystemFileHandle>(
+      mGlobal, mManager, mMetadata, mRequestHandler.release());
+
+  ASSERT_TRUE(fileHandle);
+
+  IgnoredErrorResult rv;
+  RefPtr<Promise> promise = fileHandle->GetFile(rv);
+
+  ASSERT_TRUE(rv.ErrorCodeIs(NS_ERROR_UNEXPECTED));
+}
+
+TEST_F(TestFileSystemFileHandle, isWritableReturned) {
+  RefPtr<FileSystemFileHandle> fileHandle = MakeAndAddRef<FileSystemFileHandle>(
+      mGlobal, mManager, mMetadata, mRequestHandler.release());
+
+  ASSERT_TRUE(fileHandle);
+
+  FileSystemCreateWritableOptions options;
+  IgnoredErrorResult rv;
+  RefPtr<Promise> promise = fileHandle->CreateWritable(options, rv);
+
+  ASSERT_TRUE(rv.ErrorCodeIs(NS_OK));
+}
+
+TEST_F(TestFileSystemFileHandle, doesCreateWritableFailOnNullGlobal) {
+  mGlobal = nullptr;
+  RefPtr<FileSystemFileHandle> fileHandle = MakeAndAddRef<FileSystemFileHandle>(
+      mGlobal, mManager, mMetadata, mRequestHandler.release());
+
+  ASSERT_TRUE(fileHandle);
+
+  FileSystemCreateWritableOptions options;
+  IgnoredErrorResult rv;
+  RefPtr<Promise> promise = fileHandle->CreateWritable(options, rv);
+
+  ASSERT_TRUE(rv.ErrorCodeIs(NS_ERROR_UNEXPECTED));
+}
+
+TEST_F(TestFileSystemFileHandle, isSyncAccessHandleReturned) {
+  RefPtr<FileSystemFileHandle> fileHandle = MakeAndAddRef<FileSystemFileHandle>(
+      mGlobal, mManager, mMetadata, mRequestHandler.release());
+
+  ASSERT_TRUE(fileHandle);
+
+  IgnoredErrorResult rv;
+  RefPtr<Promise> promise = fileHandle->CreateSyncAccessHandle(rv);
+
+  ASSERT_TRUE(rv.ErrorCodeIs(NS_OK));
+}
+
+TEST_F(TestFileSystemFileHandle, doesCreateSyncAccessHandleFailOnNullGlobal) {
+  mGlobal = nullptr;
+  RefPtr<FileSystemFileHandle> fileHandle = MakeAndAddRef<FileSystemFileHandle>(
+      mGlobal, mManager, mMetadata, mRequestHandler.release());
+
+  ASSERT_TRUE(fileHandle);
+
+  IgnoredErrorResult rv;
+  RefPtr<Promise> promise = fileHandle->CreateSyncAccessHandle(rv);
+
+  ASSERT_TRUE(rv.ErrorCodeIs(NS_ERROR_UNEXPECTED));
+}
+
+}  // namespace mozilla::dom::fs::test
diff --git a/dom/fs/test/gtest/api/TestFileSystemHandle.cpp b/dom/fs/test/gtest/api/TestFileSystemHandle.cpp
new file mode 100644
index 0000000000..19cdc98a84
--- /dev/null
+++ b/dom/fs/test/gtest/api/TestFileSystemHandle.cpp
@@ -0,0 +1,131 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "FileSystemMocks.h"
+#include "fs/FileSystemChildFactory.h"
+#include "gtest/gtest.h"
+#include "mozilla/dom/FileSystemDirectoryHandle.h"
+#include "mozilla/dom/FileSystemFileHandle.h"
+#include "mozilla/dom/FileSystemHandle.h"
+#include "mozilla/dom/FileSystemHandleBinding.h"
+#include "mozilla/dom/FileSystemManager.h"
+#include "mozilla/dom/StorageManager.h"
+#include "nsIGlobalObject.h"
+
+namespace mozilla::dom::fs::test {
+
+class TestFileSystemHandle : public ::testing::Test {
+ protected:
+  void SetUp() override {
+    // TODO: Fix the test to not depend on CreateFileSystemManagerParent
+    // failure because of the pref set to false.
+    nsCOMPtr<nsIPrefBranch> prefs = do_GetService(NS_PREFSERVICE_CONTRACTID);
+    prefs->SetBoolPref("dom.fs.enabled", false);
+
+    mDirMetadata = FileSystemEntryMetadata("dir"_ns, u"Directory"_ns,
+                                           /* directory */ true);
+    mFileMetadata =
+        FileSystemEntryMetadata("file"_ns, u"File"_ns, /* directory */ false);
+    mManager = MakeAndAddRef<FileSystemManager>(mGlobal, nullptr);
+  }
+
+  void TearDown() override {
+    nsCOMPtr<nsIPrefBranch> prefs = do_GetService(NS_PREFSERVICE_CONTRACTID);
+    prefs->SetBoolPref("dom.fs.enabled", true);
+
+    if (!mManager->IsShutdown()) {
+      mManager->Shutdown();
+    }
+  }
+
+  nsIGlobalObject* mGlobal = GetGlobal();
+  FileSystemEntryMetadata mDirMetadata;
+  FileSystemEntryMetadata mFileMetadata;
+  RefPtr<FileSystemManager> mManager;
+};
+
+TEST_F(TestFileSystemHandle, createAndDestroyHandles) {
+  RefPtr<FileSystemHandle> dirHandle =
+      new FileSystemDirectoryHandle(mGlobal, mManager, mDirMetadata);
+  RefPtr<FileSystemHandle> fileHandle =
+      new FileSystemFileHandle(mGlobal, mManager, mFileMetadata);
+
+  EXPECT_TRUE(dirHandle);
+  EXPECT_TRUE(fileHandle);
+}
+
+TEST_F(TestFileSystemHandle, areFileNamesAsExpected) {
+  RefPtr<FileSystemHandle> dirHandle =
+      new FileSystemDirectoryHandle(mGlobal, mManager, mDirMetadata);
+  RefPtr<FileSystemHandle> fileHandle =
+      new FileSystemFileHandle(mGlobal, mManager, mFileMetadata);
+
+  auto GetEntryName = [](const RefPtr<FileSystemHandle>& aHandle) {
+    DOMString domName;
+    aHandle->GetName(domName);
+    nsString result;
+    domName.ToString(result);
+    return result;
+  };
+
+  const nsString& dirName = GetEntryName(dirHandle);
+  EXPECT_TRUE(mDirMetadata.entryName().Equals(dirName));
+
+  const nsString& fileName = GetEntryName(fileHandle);
+  EXPECT_TRUE(mFileMetadata.entryName().Equals(fileName));
+}
+
+TEST_F(TestFileSystemHandle, isParentObjectReturned) {
+  ASSERT_TRUE(mGlobal);
+  RefPtr<FileSystemHandle> dirHandle =
+      new FileSystemDirectoryHandle(mGlobal, mManager, mDirMetadata);
+
+  ASSERT_EQ(mGlobal, dirHandle->GetParentObject());
+}
+
+TEST_F(TestFileSystemHandle, areHandleKindsAsExpected) {
+  RefPtr<FileSystemHandle> dirHandle =
+      new FileSystemDirectoryHandle(mGlobal, mManager, mDirMetadata);
+  RefPtr<FileSystemHandle> fileHandle =
+      new FileSystemFileHandle(mGlobal, mManager, mFileMetadata);
+
+  EXPECT_EQ(FileSystemHandleKind::Directory, dirHandle->Kind());
+  EXPECT_EQ(FileSystemHandleKind::File, fileHandle->Kind());
+}
+
+TEST_F(TestFileSystemHandle, isDifferentEntry) {
+  RefPtr<FileSystemHandle> dirHandle =
+      new FileSystemDirectoryHandle(mGlobal, mManager, mDirMetadata);
+  RefPtr<FileSystemHandle> fileHandle =
+      new FileSystemFileHandle(mGlobal, mManager, mFileMetadata);
+
+  IgnoredErrorResult rv;
+  RefPtr<Promise> promise = dirHandle->IsSameEntry(*fileHandle, rv);
+  ASSERT_TRUE(rv.ErrorCodeIs(NS_OK));
+  ASSERT_TRUE(promise);
+  ASSERT_EQ(Promise::PromiseState::Resolved, promise->State());
+
+  nsString result;
+  ASSERT_NSEQ(NS_OK, GetAsString(promise, result));
+  ASSERT_STREQ(u"false"_ns, result);
+}
+
+TEST_F(TestFileSystemHandle, isSameEntry) {
+  RefPtr<FileSystemHandle> fileHandle =
+      new FileSystemFileHandle(mGlobal, mManager, mFileMetadata);
+
+  IgnoredErrorResult rv;
+  RefPtr<Promise> promise = fileHandle->IsSameEntry(*fileHandle, rv);
+  ASSERT_TRUE(rv.ErrorCodeIs(NS_OK));
+  ASSERT_TRUE(promise);
+  ASSERT_EQ(Promise::PromiseState::Resolved, promise->State());
+
+  nsString result;
+  ASSERT_NSEQ(NS_OK, GetAsString(promise, result));
+  ASSERT_STREQ(u"true"_ns, result);
+}
+
+}  // namespace mozilla::dom::fs::test
diff --git a/dom/fs/test/gtest/api/moz.build b/dom/fs/test/gtest/api/moz.build
new file mode 100644
index 0000000000..eb8416a3ba
--- /dev/null
+++ b/dom/fs/test/gtest/api/moz.build
@@ -0,0 +1,21 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, you can obtain one at http://mozilla.org/MPL/2.0/.
+
+UNIFIED_SOURCES = [
+    "TestFileSystemDirectoryHandle.cpp",
+    "TestFileSystemFileHandle.cpp",
+    "TestFileSystemHandle.cpp",
+]
+
+include("/ipc/chromium/chromium-config.mozbuild")
+
+FINAL_LIBRARY = "xul-gtest"
+
+LOCAL_INCLUDES += [
+    "/dom/fs/api",
+    "/dom/fs/include",
+    "/dom/fs/test/gtest",
+]
diff --git a/dom/fs/test/gtest/child/TestFileSystemBackgroundRequestHandler.cpp b/dom/fs/test/gtest/child/TestFileSystemBackgroundRequestHandler.cpp
new file mode 100644
index 0000000000..48d63cfc36
--- /dev/null
+++ b/dom/fs/test/gtest/child/TestFileSystemBackgroundRequestHandler.cpp
@@ -0,0 +1,64 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "FileSystemBackgroundRequestHandler.h"
+#include "FileSystemMocks.h"
+#include "gtest/gtest.h"
+#include "mozilla/SpinEventLoopUntil.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/dom/FileSystemManager.h"
+#include "mozilla/dom/FileSystemManagerChild.h"
+#include "mozilla/dom/PFileSystemManager.h"
+
+namespace mozilla::dom::fs::test {
+
+class TestFileSystemBackgroundRequestHandler : public ::testing::Test {
+ protected:
+  void SetUp() override {
+    // TODO: Fix the test to not depend on CreateFileSystemManagerParent
+    // failure because of the pref set to false.
+    nsCOMPtr<nsIPrefBranch> prefs = do_GetService(NS_PREFSERVICE_CONTRACTID);
+    prefs->SetBoolPref("dom.fs.enabled", false);
+
+    mFileSystemManagerChild = MakeAndAddRef<TestFileSystemManagerChild>();
+  }
+
+  void TearDown() override {
+    nsCOMPtr<nsIPrefBranch> prefs = do_GetService(NS_PREFSERVICE_CONTRACTID);
+    prefs->SetBoolPref("dom.fs.enabled", true);
+  }
+
+  RefPtr<FileSystemBackgroundRequestHandler>
+  GetFileSystemBackgroundRequestHandler() {
+    return MakeRefPtr<FileSystemBackgroundRequestHandler>(
+        new TestFileSystemChildFactory(mFileSystemManagerChild));
+  }
+
+  mozilla::ipc::PrincipalInfo mPrincipalInfo = GetPrincipalInfo();
+  RefPtr<TestFileSystemManagerChild> mFileSystemManagerChild;
+};
+
+TEST_F(TestFileSystemBackgroundRequestHandler,
+       isCreateFileSystemManagerChildSuccessful) {
+  EXPECT_CALL(*mFileSystemManagerChild, Shutdown())
+      .WillOnce([fileSystemManagerChild =
+                     static_cast<void*>(mFileSystemManagerChild.get())]() {
+        static_cast<TestFileSystemManagerChild*>(fileSystemManagerChild)
+            ->FileSystemManagerChild::Shutdown();
+      });
+
+  bool done = false;
+  auto testable = GetFileSystemBackgroundRequestHandler();
+  testable->CreateFileSystemManagerChild(mPrincipalInfo)
+      ->Then(
+          GetCurrentSerialEventTarget(), __func__,
+          [&done](bool) { done = true; }, [&done](nsresult) { done = true; });
+  // MozPromise should be rejected
+  SpinEventLoopUntil("Promise is fulfilled or timeout"_ns,
+                     [&done]() { return done; });
+}
+
+}  // namespace mozilla::dom::fs::test
diff --git a/dom/fs/test/gtest/child/TestFileSystemRequestHandler.cpp b/dom/fs/test/gtest/child/TestFileSystemRequestHandler.cpp
new file mode 100644
index 0000000000..c2832103af
--- /dev/null
+++ b/dom/fs/test/gtest/child/TestFileSystemRequestHandler.cpp
@@ -0,0 +1,352 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "FileSystemBackgroundRequestHandler.h"
+#include "FileSystemEntryMetadataArray.h"
+#include "FileSystemMocks.h"
+#include "fs/FileSystemRequestHandler.h"
+#include "gtest/gtest.h"
+#include "mozilla/SpinEventLoopUntil.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/dom/FileBlobImpl.h"
+#include "mozilla/dom/FileSystemManager.h"
+#include "mozilla/dom/FileSystemManagerChild.h"
+#include "mozilla/dom/IPCBlob.h"
+#include "mozilla/dom/IPCBlobUtils.h"
+#include "mozilla/dom/PFileSystemManager.h"
+#include "mozilla/dom/StorageManager.h"
+#include "mozilla/ipc/FileDescriptorUtils.h"
+#include "mozilla/ipc/IPCCore.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsIFile.h"
+
+using ::testing::_;
+using ::testing::ByRef;
+using ::testing::Invoke;
+using ::testing::Return;
+
+namespace mozilla::dom::fs::test {
+
+class TestFileSystemRequestHandler : public ::testing::Test {
+ protected:
+  void SetUp() override {
+    mListener = MakeAndAddRef<ExpectResolveCalled>();
+
+    mChild = FileSystemChildMetadata("parent"_ns, u"ChildName"_ns);
+    mEntry = FileSystemEntryMetadata("myid"_ns, u"EntryName"_ns,
+                                     /* directory */ false);
+    mName = u"testDir"_ns;
+    mFileSystemManagerChild = MakeAndAddRef<TestFileSystemManagerChild>();
+    mManager = MakeAndAddRef<FileSystemManager>(
+        mGlobal, nullptr,
+        MakeRefPtr<FileSystemBackgroundRequestHandler>(
+            mFileSystemManagerChild));
+  }
+
+  void TearDown() override {
+    if (!mManager->IsShutdown()) {
+      EXPECT_NO_FATAL_FAILURE(ShutdownFileSystemManager());
+    }
+  }
+
+  already_AddRefed<Promise> GetDefaultPromise() {
+    IgnoredErrorResult rv;
+    RefPtr<Promise> result = Promise::Create(mGlobal, rv);
+    mListener->ClearDone();
+    result->AppendNativeHandler(mListener->AsHandler());
+
+    return result.forget();
+  }
+
+  already_AddRefed<Promise> GetSimplePromise() {
+    IgnoredErrorResult rv;
+    RefPtr<Promise> result = Promise::Create(mGlobal, rv);
+
+    return result.forget();
+  }
+
+  already_AddRefed<Promise> GetShutdownPromise() {
+    RefPtr<Promise> promise = GetDefaultPromise();
+    EXPECT_CALL(*mFileSystemManagerChild, Shutdown())
+        .WillOnce(Invoke([promise]() { promise->MaybeResolveWithUndefined(); }))
+        .WillOnce(Return());
+    EXPECT_CALL(mListener->GetSuccessHandler(), InvokeMe());
+
+    return promise.forget();
+  }
+
+  UniquePtr<FileSystemRequestHandler> GetFileSystemRequestHandler() {
+    return MakeUnique<FileSystemRequestHandler>();
+  }
+
+  void ShutdownFileSystemManager() {
+    RefPtr<Promise> promise = GetShutdownPromise();
+
+    mManager->Shutdown();
+
+    SpinEventLoopUntil("Promise is fulfilled or timeout"_ns,
+                       [this]() { return mListener->IsDone(); });
+    ASSERT_TRUE(mManager->IsShutdown());
+  }
+
+  nsIGlobalObject* mGlobal = GetGlobal();
+  RefPtr<ExpectResolveCalled> mListener;
+
+  FileSystemChildMetadata mChild;
+  FileSystemEntryMetadata mEntry;
+  nsString mName;
+  RefPtr<TestFileSystemManagerChild> mFileSystemManagerChild;
+  RefPtr<FileSystemManager> mManager;
+};
+
+TEST_F(TestFileSystemRequestHandler, isGetRootHandleSuccessful) {
+  auto fakeResponse = [](auto&& aResolve, auto&& /* aReject */) {
+    EntryId expected = "expected"_ns;
+    FileSystemGetHandleResponse response(expected);
+    aResolve(std::move(response));
+  };
+
+  EXPECT_CALL(mListener->GetSuccessHandler(), InvokeMe());
+  EXPECT_CALL(*mFileSystemManagerChild, SendGetRootHandle(_, _))
+      .WillOnce(Invoke(fakeResponse));
+
+  RefPtr<Promise> promise = GetDefaultPromise();
+  auto testable = GetFileSystemRequestHandler();
+  testable->GetRootHandle(mManager, promise, IgnoredErrorResult());
+  SpinEventLoopUntil("Promise is fulfilled or timeout"_ns,
+                     [this]() { return mListener->IsDone(); });
+}
+
+TEST_F(TestFileSystemRequestHandler, isGetRootHandleBlockedAfterShutdown) {
+  ASSERT_NO_FATAL_FAILURE(ShutdownFileSystemManager());
+
+  IgnoredErrorResult error;
+  GetFileSystemRequestHandler()->GetRootHandle(mManager, GetSimplePromise(),
+                                               error);
+
+  ASSERT_TRUE(error.Failed());
+  ASSERT_TRUE(error.ErrorCodeIs(NS_ERROR_ILLEGAL_DURING_SHUTDOWN));
+}
+
+TEST_F(TestFileSystemRequestHandler, isGetDirectoryHandleSuccessful) {
+  auto fakeResponse = [](const auto& /* aRequest */, auto&& aResolve,
+                         auto&& /* aReject */) {
+    EntryId expected = "expected"_ns;
+    FileSystemGetHandleResponse response(expected);
+    aResolve(std::move(response));
+  };
+
+  EXPECT_CALL(mListener->GetSuccessHandler(), InvokeMe());
+  EXPECT_CALL(*mFileSystemManagerChild, SendGetDirectoryHandle(_, _, _))
+      .WillOnce(Invoke(fakeResponse));
+
+  RefPtr<Promise> promise = GetDefaultPromise();
+  auto testable = GetFileSystemRequestHandler();
+  testable->GetDirectoryHandle(mManager, mChild,
+                               /* create */ true, promise,
+                               IgnoredErrorResult());
+  SpinEventLoopUntil("Promise is fulfilled or timeout"_ns,
+                     [this]() { return mListener->IsDone(); });
+}
+
+TEST_F(TestFileSystemRequestHandler, isGetDirectoryHandleBlockedAfterShutdown) {
+  ASSERT_NO_FATAL_FAILURE(ShutdownFileSystemManager());
+
+  IgnoredErrorResult error;
+  GetFileSystemRequestHandler()->GetDirectoryHandle(
+      mManager, mChild, /* aCreate */ true, GetSimplePromise(), error);
+
+  ASSERT_TRUE(error.Failed());
+  ASSERT_TRUE(error.ErrorCodeIs(NS_ERROR_ILLEGAL_DURING_SHUTDOWN));
+}
+
+TEST_F(TestFileSystemRequestHandler, isGetFileHandleSuccessful) {
+  auto fakeResponse = [](const auto& /* aRequest */, auto&& aResolve,
+                         auto&& /* aReject */) {
+    EntryId expected = "expected"_ns;
+    FileSystemGetHandleResponse response(expected);
+    aResolve(std::move(response));
+  };
+
+  EXPECT_CALL(mListener->GetSuccessHandler(), InvokeMe());
+  EXPECT_CALL(*mFileSystemManagerChild, SendGetFileHandle(_, _, _))
+      .WillOnce(Invoke(fakeResponse));
+
+  RefPtr<Promise> promise = GetDefaultPromise();
+  auto testable = GetFileSystemRequestHandler();
+  testable->GetFileHandle(mManager, mChild, /* create */ true, promise,
+                          IgnoredErrorResult());
+  SpinEventLoopUntil("Promise is fulfilled or timeout"_ns,
+                     [this]() { return mListener->IsDone(); });
+}
+
+TEST_F(TestFileSystemRequestHandler, isGetFileHandleBlockedAfterShutdown) {
+  ASSERT_NO_FATAL_FAILURE(ShutdownFileSystemManager());
+
+  IgnoredErrorResult error;
+  GetFileSystemRequestHandler()->GetFileHandle(
+      mManager, mChild, /* aCreate */ true, GetSimplePromise(), error);
+
+  ASSERT_TRUE(error.Failed());
+  ASSERT_TRUE(error.ErrorCodeIs(NS_ERROR_ILLEGAL_DURING_SHUTDOWN));
+}
+
+TEST_F(TestFileSystemRequestHandler, isGetFileSuccessful) {
+  auto fakeResponse = [](const auto& /* aRequest */, auto&& aResolve,
+                         auto&& /* aReject */) {
+    // We have to create a temporary file
+    nsCOMPtr<nsIFile> tmpfile;
+    nsresult rv =
+        NS_GetSpecialDirectory(NS_OS_TEMP_DIR, getter_AddRefs(tmpfile));
+    ASSERT_EQ(NS_SUCCEEDED(rv), true);
+
+    rv = tmpfile->AppendNative("GetFileTestBlob"_ns);
+    ASSERT_EQ(NS_SUCCEEDED(rv), true);
+
+    rv = tmpfile->CreateUnique(nsIFile::NORMAL_FILE_TYPE, 0666);
+    ASSERT_EQ(NS_SUCCEEDED(rv), true);
+
+    auto blob = MakeRefPtr<FileBlobImpl>(tmpfile);
+
+    TimeStamp last_modified_ms = 0;
+    ContentType type = "txt"_ns;
+    IPCBlob file;
+    IPCBlobUtils::Serialize(blob, file);
+
+    nsTArray<Name> path;
+    path.AppendElement(u"root"_ns);
+    path.AppendElement(u"Trash"_ns);
+
+    FileSystemFileProperties properties(last_modified_ms, file, type, path);
+    FileSystemGetFileResponse response(properties);
+    aResolve(std::move(response));
+  };
+
+  EXPECT_CALL(mListener->GetSuccessHandler(), InvokeMe());
+  EXPECT_CALL(*mFileSystemManagerChild, SendGetFile(_, _, _))
+      .WillOnce(Invoke(fakeResponse));
+
+  RefPtr<Promise> promise = GetDefaultPromise();
+  auto testable = GetFileSystemRequestHandler();
+  testable->GetFile(mManager, mEntry, promise, IgnoredErrorResult());
+  SpinEventLoopUntil("Promise is fulfilled or timeout"_ns,
+                     [this]() { return mListener->IsDone(); });
+}
+
+TEST_F(TestFileSystemRequestHandler, isGetFileBlockedAfterShutdown) {
+  ASSERT_NO_FATAL_FAILURE(ShutdownFileSystemManager());
+
+  IgnoredErrorResult error;
+  GetFileSystemRequestHandler()->GetFile(mManager, mEntry, GetSimplePromise(),
+                                         error);
+
+  ASSERT_TRUE(error.Failed());
+  ASSERT_TRUE(error.ErrorCodeIs(NS_ERROR_ILLEGAL_DURING_SHUTDOWN));
+}
+
+TEST_F(TestFileSystemRequestHandler, isGetAccessHandleBlockedAfterShutdown) {
+  RefPtr<Promise> promise = GetShutdownPromise();
+
+  mManager->Shutdown();
+
+  SpinEventLoopUntil("Promise is fulfilled or timeout"_ns,
+                     [this]() { return mListener->IsDone(); });
+  ASSERT_TRUE(mManager->IsShutdown());
+
+  IgnoredErrorResult error;
+  GetFileSystemRequestHandler()->GetAccessHandle(mManager, mEntry,
+                                                 GetSimplePromise(), error);
+
+  ASSERT_TRUE(error.Failed());
+  ASSERT_TRUE(error.ErrorCodeIs(NS_ERROR_ILLEGAL_DURING_SHUTDOWN));
+}
+
+TEST_F(TestFileSystemRequestHandler, isGetWritableBlockedAfterShutdown) {
+  ASSERT_NO_FATAL_FAILURE(ShutdownFileSystemManager());
+
+  IgnoredErrorResult error;
+  GetFileSystemRequestHandler()->GetWritable(
+      mManager, mEntry, /* aKeepData */ false, GetSimplePromise(), error);
+
+  ASSERT_TRUE(error.Failed());
+  ASSERT_TRUE(error.ErrorCodeIs(NS_ERROR_ILLEGAL_DURING_SHUTDOWN));
+}
+
+TEST_F(TestFileSystemRequestHandler, isGetEntriesSuccessful) {
+  auto fakeResponse = [](const auto& /* aRequest */, auto&& aResolve,
+                         auto&& /* aReject */) {
+    nsTArray<FileSystemEntryMetadata> files;
+    nsTArray<FileSystemEntryMetadata> directories;
+    FileSystemDirectoryListing listing(files, directories);
+    FileSystemGetEntriesResponse response(listing);
+    aResolve(std::move(response));
+  };
+
+  RefPtr<ExpectResolveCalled> listener = MakeAndAddRef<ExpectResolveCalled>();
+  IgnoredErrorResult rv;
+  listener->ClearDone();
+  EXPECT_CALL(listener->GetSuccessHandler(), InvokeMe());
+
+  RefPtr<Promise> promise = Promise::Create(mGlobal, rv);
+  promise->AppendNativeHandler(listener);
+
+  EXPECT_CALL(*mFileSystemManagerChild, SendGetEntries(_, _, _))
+      .WillOnce(Invoke(fakeResponse));
+
+  auto testable = GetFileSystemRequestHandler();
+  RefPtr<FileSystemEntryMetadataArray> sink;
+
+  testable->GetEntries(mManager, mEntry.entryId(), /* page */ 0, promise, sink,
+                       IgnoredErrorResult());
+  SpinEventLoopUntil("Promise is fulfilled or timeout"_ns,
+                     [listener]() { return listener->IsDone(); });
+}
+
+TEST_F(TestFileSystemRequestHandler, isGetEntriesBlockedAfterShutdown) {
+  ASSERT_NO_FATAL_FAILURE(ShutdownFileSystemManager());
+
+  RefPtr<FileSystemEntryMetadataArray> sink;
+
+  IgnoredErrorResult error;
+  GetFileSystemRequestHandler()->GetEntries(mManager, mEntry.entryId(),
+                                            /* aPage */ 0, GetSimplePromise(),
+                                            sink, error);
+
+  ASSERT_TRUE(error.Failed());
+  ASSERT_TRUE(error.ErrorCodeIs(NS_ERROR_ILLEGAL_DURING_SHUTDOWN));
+}
+
+TEST_F(TestFileSystemRequestHandler, isRemoveEntrySuccessful) {
+  auto fakeResponse = [](const auto& /* aRequest */, auto&& aResolve,
+                         auto&& /* aReject */) {
+    FileSystemRemoveEntryResponse response(mozilla::void_t{});
+    aResolve(std::move(response));
+  };
+
+  EXPECT_CALL(mListener->GetSuccessHandler(), InvokeMe());
+  EXPECT_CALL(*mFileSystemManagerChild, SendRemoveEntry(_, _, _))
+      .WillOnce(Invoke(fakeResponse));
+
+  auto testable = GetFileSystemRequestHandler();
+  RefPtr<Promise> promise = GetDefaultPromise();
+  testable->RemoveEntry(mManager, mChild, /* recursive */ true, promise,
+                        IgnoredErrorResult());
+  SpinEventLoopUntil("Promise is fulfilled or timeout"_ns,
+                     [this]() { return mListener->IsDone(); });
+}
+
+TEST_F(TestFileSystemRequestHandler, isRemoveEntryBlockedAfterShutdown) {
+  ASSERT_NO_FATAL_FAILURE(ShutdownFileSystemManager());
+
+  IgnoredErrorResult error;
+  GetFileSystemRequestHandler()->RemoveEntry(
+      mManager, mChild, /* aRecursive */ true, GetSimplePromise(), error);
+
+  ASSERT_TRUE(error.Failed());
+  ASSERT_TRUE(error.ErrorCodeIs(NS_ERROR_ILLEGAL_DURING_SHUTDOWN));
+}
+
+}  // namespace mozilla::dom::fs::test
diff --git a/dom/fs/test/gtest/child/moz.build b/dom/fs/test/gtest/child/moz.build
new file mode 100644
index 0000000000..c305ab1f2e
--- /dev/null
+++ b/dom/fs/test/gtest/child/moz.build
@@ -0,0 +1,20 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, you can obtain one at http://mozilla.org/MPL/2.0/.
+
+UNIFIED_SOURCES = [
+    "TestFileSystemBackgroundRequestHandler.cpp",
+    "TestFileSystemRequestHandler.cpp",
+]
+
+include("/ipc/chromium/chromium-config.mozbuild")
+
+FINAL_LIBRARY = "xul-gtest"
+
+LOCAL_INCLUDES += [
+    "/dom/fs/child",
+    "/dom/fs/include",
+    "/dom/fs/test/gtest",
+]
diff --git a/dom/fs/test/gtest/moz.build b/dom/fs/test/gtest/moz.build
new file mode 100644
index 0000000000..81be2a3d33
--- /dev/null
+++ b/dom/fs/test/gtest/moz.build
@@ -0,0 +1,25 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+TEST_DIRS += [
+    "api",
+    "child",
+    "parent",
+    "shared",
+]
+
+UNIFIED_SOURCES = [
+    "FileSystemMocks.cpp",
+    "TestHelpers.cpp",
+]
+
+include("/ipc/chromium/chromium-config.mozbuild")
+
+FINAL_LIBRARY = "xul-gtest"
+
+LOCAL_INCLUDES += [
+    "/dom/fs/include",
+]
diff --git a/dom/fs/test/gtest/parent/TestFileSystemHashSource.cpp b/dom/fs/test/gtest/parent/TestFileSystemHashSource.cpp
new file mode 100644
index 0000000000..1764763dd5
--- /dev/null
+++ b/dom/fs/test/gtest/parent/TestFileSystemHashSource.cpp
@@ -0,0 +1,183 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "FileSystemHashSource.h"
+#include "FileSystemParentTypes.h"
+#include "TestHelpers.h"
+#include "gtest/gtest.h"
+#include "mozilla/Array.h"
+#include "mozilla/dom/FileSystemTypes.h"
+#include "nsContentUtils.h"
+#include "nsLiteralString.h"
+#include "nsString.h"
+#include "nsStringFwd.h"
+#include "nsTArray.h"
+#include "nsTHashSet.h"
+
+namespace mozilla::dom::fs::test {
+
+using mozilla::dom::fs::data::FileSystemHashSource;
+
+namespace {
+
+constexpr size_t sha256ByteLength = 32u;
+
+constexpr size_t kExpectedLength = 52u;
+
+std::wstring asWide(const nsString& aStr) {
+  std::wstring result;
+  result.reserve(aStr.Length());
+  for (const auto* it = aStr.BeginReading(); it != aStr.EndReading(); ++it) {
+    result.push_back(static_cast<wchar_t>(*it));
+  }
+  return result;
+}
+
+}  // namespace
+
+TEST(TestFileSystemHashSource, isHashLengthAsExpected)
+{
+  EntryId parent = "a"_ns;
+  Name name = u"b"_ns;
+  TEST_TRY_UNWRAP(EntryId result,
+                  FileSystemHashSource::GenerateHash(parent, name));
+  ASSERT_EQ(sha256ByteLength, result.Length());
+};
+
+TEST(TestFileSystemHashSource, areNestedNameHashesValidAndUnequal)
+{
+  EntryId emptyParent = ""_ns;
+  Name name = u"a"_ns;
+  const size_t nestingNumber = 500u;
+
+  nsTHashSet<EntryId> results;
+  nsTHashSet<Name> names;
+
+  auto previousParent = emptyParent;
+  for (size_t i = 0; i < nestingNumber; ++i) {
+    TEST_TRY_UNWRAP(EntryId result,
+                    FileSystemHashSource::GenerateHash(previousParent, name));
+
+    TEST_TRY_UNWRAP(Name encoded,
+                    FileSystemHashSource::EncodeHash(FileId(result)));
+
+    // Validity checks
+    ASSERT_TRUE(mozilla::IsAscii(encoded))
+    << encoded;
+    Name upperCaseVersion;
+    nsContentUtils::ASCIIToUpper(encoded, upperCaseVersion);
+    ASSERT_STREQ(asWide(upperCaseVersion).c_str(), asWide(encoded).c_str());
+
+    // Is the same hash encountered?
+    ASSERT_FALSE(results.Contains(result));
+    ASSERT_TRUE(results.Insert(result, mozilla::fallible));
+
+    // Is the same name encountered?
+    ASSERT_FALSE(names.Contains(encoded));
+    ASSERT_TRUE(names.Insert(encoded, mozilla::fallible));
+
+    previousParent = result;
+  }
+};
+
+TEST(TestFileSystemHashSource, areNameCombinationHashesUnequal)
+{
+  EntryId emptyParent = ""_ns;
+
+  mozilla::Array<Name, 2> inputs = {u"a"_ns, u"b"_ns};
+  nsTArray<EntryId> results;
+  nsTArray<Name> names;
+
+  for (const auto& name : inputs) {
+    TEST_TRY_UNWRAP(EntryId result,
+                    FileSystemHashSource::GenerateHash(emptyParent, name));
+    TEST_TRY_UNWRAP(Name encoded,
+                    FileSystemHashSource::EncodeHash(FileId(result)));
+
+    // Validity checks
+    ASSERT_TRUE(mozilla::IsAscii(encoded))
+    << encoded;
+    Name upperCaseVersion;
+    nsContentUtils::ASCIIToUpper(encoded, upperCaseVersion);
+    ASSERT_STREQ(asWide(upperCaseVersion).c_str(), asWide(encoded).c_str());
+
+    results.AppendElement(result);
+    names.AppendElement(encoded);
+  }
+
+  nsTArray<EntryId> more_results;
+  nsTArray<Name> more_names;
+  for (const auto& parent : results) {
+    for (const auto& name : inputs) {
+      TEST_TRY_UNWRAP(EntryId result,
+                      FileSystemHashSource::GenerateHash(parent, name));
+      TEST_TRY_UNWRAP(Name encoded,
+                      FileSystemHashSource::EncodeHash(FileId(result)));
+
+      // Validity checks
+      ASSERT_TRUE(mozilla::IsAscii(encoded))
+      << encoded;
+      Name upperCaseVersion;
+      nsContentUtils::ASCIIToUpper(encoded, upperCaseVersion);
+      ASSERT_STREQ(asWide(upperCaseVersion).c_str(), asWide(encoded).c_str());
+
+      more_results.AppendElement(result);
+      more_names.AppendElement(encoded);
+    }
+  }
+
+  results.AppendElements(more_results);
+  names.AppendElements(more_names);
+
+  // Is the same hash encountered?
+  for (size_t i = 0; i < results.Length(); ++i) {
+    for (size_t j = i + 1; j < results.Length(); ++j) {
+      ASSERT_STRNE(results[i].get(), results[j].get());
+    }
+  }
+
+  // Is the same name encountered?
+  for (size_t i = 0; i < names.Length(); ++i) {
+    for (size_t j = i + 1; j < names.Length(); ++j) {
+      ASSERT_STRNE(asWide(names[i]).c_str(), asWide(names[j]).c_str());
+    }
+  }
+};
+
+TEST(TestFileSystemHashSource, encodeGeneratedHash)
+{
+  Name expected = u"HF6FOFV72G3NMDEJKYMVRIFJO4X5ZNZCF2GM7Q4Y5Q3E7NPQKSLA"_ns;
+  ASSERT_EQ(kExpectedLength, expected.Length());
+
+  EntryId parent = "a"_ns;
+  Name name = u"b"_ns;
+  TEST_TRY_UNWRAP(EntryId entry,
+                  FileSystemHashSource::GenerateHash(parent, name));
+  ASSERT_EQ(sha256ByteLength, entry.Length());
+
+  TEST_TRY_UNWRAP(Name result, FileSystemHashSource::EncodeHash(FileId(entry)));
+  ASSERT_EQ(kExpectedLength, result.Length());
+  ASSERT_STREQ(asWide(expected).c_str(), asWide(result).c_str());
+
+  // Generate further hashes
+  TEST_TRY_UNWRAP(entry, FileSystemHashSource::GenerateHash(entry, result));
+  ASSERT_EQ(sha256ByteLength, entry.Length());
+
+  TEST_TRY_UNWRAP(result, FileSystemHashSource::EncodeHash(FileId(entry)));
+
+  // Always the same length
+  ASSERT_EQ(kExpectedLength, result.Length());
+
+  // Encoded versions should differ
+  ASSERT_STRNE(asWide(expected).c_str(), asWide(result).c_str());
+
+  // Padding length should have been stripped
+  char16_t padding = u"="_ns[0];
+  const int32_t paddingStart = result.FindChar(padding);
+  ASSERT_EQ(-1, paddingStart);
+};
+
+}  // namespace mozilla::dom::fs::test
diff --git a/dom/fs/test/gtest/parent/TestFileSystemQuotaClient.cpp b/dom/fs/test/gtest/parent/TestFileSystemQuotaClient.cpp
new file mode 100644
index 0000000000..d62dfb1229
--- /dev/null
+++ b/dom/fs/test/gtest/parent/TestFileSystemQuotaClient.cpp
@@ -0,0 +1,474 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "FileSystemParentTypes.h"
+#include "TestHelpers.h"
+#include "datamodel/FileSystemDataManager.h"
+#include "datamodel/FileSystemDatabaseManager.h"
+#include "datamodel/FileSystemFileManager.h"
+#include "gtest/gtest.h"
+#include "mozIStorageService.h"
+#include "mozStorageCID.h"
+#include "mozilla/SpinEventLoopUntil.h"
+#include "mozilla/dom/FileSystemQuotaClientFactory.h"
+#include "mozilla/dom/PFileSystemManager.h"
+#include "mozilla/dom/ScriptSettings.h"
+#include "mozilla/dom/quota/FileStreams.h"
+#include "mozilla/dom/quota/QuotaCommon.h"
+#include "mozilla/dom/quota/QuotaManager.h"
+#include "mozilla/dom/quota/QuotaManagerService.h"
+#include "mozilla/dom/quota/ResultExtensions.h"
+#include "mozilla/dom/quota/UsageInfo.h"
+#include "mozilla/dom/quota/test/QuotaManagerDependencyFixture.h"
+#include "mozilla/gtest/MozAssertions.h"
+#include "nsIFile.h"
+#include "nsIFileURL.h"
+#include "nsIPrefBranch.h"
+#include "nsIPrefService.h"
+#include "nsIQuotaCallbacks.h"
+#include "nsIQuotaRequests.h"
+#include "nsNetUtil.h"
+#include "nsScriptSecurityManager.h"
+
+namespace mozilla::dom::fs::test {
+
+quota::OriginMetadata GetTestQuotaOriginMetadata() {
+  return quota::OriginMetadata{""_ns,
+                               "quotaexample.com"_ns,
+                               "http://quotaexample.com"_ns,
+                               "http://quotaexample.com"_ns,
+                               /* aIsPrivate */ false,
+                               quota::PERSISTENCE_TYPE_DEFAULT};
+}
+
+class TestFileSystemQuotaClient
+    : public quota::test::QuotaManagerDependencyFixture {
+ public:
+  static const int sPage = 64 * 512;
+  // ExceedsPreallocation value may depend on platform and sqlite version!
+  static const int sExceedsPreallocation = sPage;
+
+ protected:
+  void SetUp() override { ASSERT_NO_FATAL_FAILURE(InitializeFixture()); }
+
+  void TearDown() override {
+    EXPECT_NO_FATAL_FAILURE(
+        ClearStoragesForOrigin(GetTestQuotaOriginMetadata()));
+    ASSERT_NO_FATAL_FAILURE(ShutdownFixture());
+  }
+
+  static const Name& GetTestFileName() {
+    static Name testFileName = []() {
+      nsCString testCFileName;
+      testCFileName.SetLength(sExceedsPreallocation);
+      std::fill(testCFileName.BeginWriting(), testCFileName.EndWriting(), 'x');
+      return NS_ConvertASCIItoUTF16(testCFileName.BeginReading(),
+                                    sExceedsPreallocation);
+    }();
+
+    return testFileName;
+  }
+
+  static uint64_t BytesOfName(const Name& aName) {
+    return static_cast<uint64_t>(aName.Length() * sizeof(Name::char_type));
+  }
+
+  static const nsCString& GetTestData() {
+    static const nsCString sTestData = "There is a way out of every box"_ns;
+    return sTestData;
+  }
+
+  static void CreateNewEmptyFile(
+      data::FileSystemDatabaseManager* const aDatabaseManager,
+      const FileSystemChildMetadata& aFileSlot, EntryId& aEntryId) {
+    // The file should not exist yet
+    Result<EntryId, QMResult> existingTestFile =
+        aDatabaseManager->GetOrCreateFile(aFileSlot, /* create */ false);
+    ASSERT_TRUE(existingTestFile.isErr());
+    ASSERT_NSEQ(NS_ERROR_DOM_NOT_FOUND_ERR,
+                ToNSResult(existingTestFile.unwrapErr()));
+
+    // Create a new file
+    TEST_TRY_UNWRAP(aEntryId, aDatabaseManager->GetOrCreateFile(
+                                  aFileSlot, /* create */ true));
+  }
+
+  static void WriteDataToFile(
+      data::FileSystemDatabaseManager* const aDatabaseManager,
+      const EntryId& aEntryId, const nsCString& aData) {
+    TEST_TRY_UNWRAP(FileId fileId, aDatabaseManager->EnsureFileId(aEntryId));
+    ASSERT_FALSE(fileId.IsEmpty());
+
+    ContentType type;
+    TimeStamp lastModMilliS = 0;
+    Path path;
+    nsCOMPtr<nsIFile> fileObj;
+    ASSERT_NSEQ(NS_OK,
+                aDatabaseManager->GetFile(aEntryId, fileId, FileMode::EXCLUSIVE,
+                                          type, lastModMilliS, path, fileObj));
+
+    uint32_t written = 0;
+    ASSERT_NE(written, aData.Length());
+
+    const quota::OriginMetadata& testOriginMeta = GetTestQuotaOriginMetadata();
+
+    TEST_TRY_UNWRAP(nsCOMPtr<nsIOutputStream> fileStream,
+                    quota::CreateFileOutputStream(
+                        quota::PERSISTENCE_TYPE_DEFAULT, testOriginMeta,
+                        quota::Client::FILESYSTEM, fileObj));
+
+    auto finallyClose = MakeScopeExit(
+        [&fileStream]() { ASSERT_NSEQ(NS_OK, fileStream->Close()); });
+    ASSERT_NSEQ(NS_OK,
+                fileStream->Write(aData.get(), aData.Length(), &written));
+
+    ASSERT_EQ(aData.Length(), written);
+  }
+
+  /* Static for use in callbacks */
+  static void CreateRegisteredDataManager(
+      Registered<data::FileSystemDataManager>& aRegisteredDataManager) {
+    bool done = false;
+
+    data::FileSystemDataManager::GetOrCreateFileSystemDataManager(
+        GetTestQuotaOriginMetadata())
+        ->Then(
+            GetCurrentSerialEventTarget(), __func__,
+            [&aRegisteredDataManager,
+             &done](Registered<data::FileSystemDataManager>
+                        registeredDataManager) mutable {
+              auto doneOnReturn = MakeScopeExit([&done]() { done = true; });
+
+              ASSERT_TRUE(registeredDataManager->IsOpen());
+              aRegisteredDataManager = std::move(registeredDataManager);
+            },
+            [&done](nsresult rejectValue) {
+              auto doneOnReturn = MakeScopeExit([&done]() { done = true; });
+
+              ASSERT_NSEQ(NS_OK, rejectValue);
+            });
+
+    SpinEventLoopUntil("Promise is fulfilled"_ns, [&done]() { return done; });
+
+    ASSERT_TRUE(aRegisteredDataManager);
+    ASSERT_TRUE(aRegisteredDataManager->IsOpen());
+    ASSERT_TRUE(aRegisteredDataManager->MutableDatabaseManagerPtr());
+  }
+
+  static void CheckUsageEqualTo(const quota::UsageInfo& aUsage,
+                                uint64_t expected) {
+    EXPECT_TRUE(aUsage.FileUsage().isNothing());
+    auto dbUsage = aUsage.DatabaseUsage();
+    ASSERT_TRUE(dbUsage.isSome());
+    const auto actual = dbUsage.value();
+    ASSERT_EQ(actual, expected);
+  }
+
+  static void CheckUsageGreaterThan(const quota::UsageInfo& aUsage,
+                                    uint64_t expected) {
+    EXPECT_TRUE(aUsage.FileUsage().isNothing());
+    auto dbUsage = aUsage.DatabaseUsage();
+    ASSERT_TRUE(dbUsage.isSome());
+    const auto actual = dbUsage.value();
+    ASSERT_GT(actual, expected);
+  }
+};
+
+TEST_F(TestFileSystemQuotaClient, CheckUsageBeforeAnyFilesOnDisk) {
+  auto backgroundTask = []() {
+    mozilla::Atomic<bool> isCanceled{false};
+    auto ioTask = [&isCanceled](const RefPtr<quota::Client>& quotaClient,
+                                data::FileSystemDatabaseManager* dbm) {
+      ASSERT_FALSE(isCanceled);
+      const quota::OriginMetadata& testOriginMeta =
+          GetTestQuotaOriginMetadata();
+      const Origin& testOrigin = testOriginMeta.mOrigin;
+
+      // After initialization,
+      // * database size is not zero
+      // * GetUsageForOrigin and InitOrigin should agree
+      TEST_TRY_UNWRAP(quota::UsageInfo usageNow,
+                      quotaClient->InitOrigin(quota::PERSISTENCE_TYPE_DEFAULT,
+                                              testOriginMeta, isCanceled));
+      ASSERT_NO_FATAL_FAILURE(CheckUsageGreaterThan(usageNow, 0u));
+      const auto initialDbUsage = usageNow.DatabaseUsage().value();
+
+      TEST_TRY_UNWRAP(usageNow, quotaClient->GetUsageForOrigin(
+                                    quota::PERSISTENCE_TYPE_DEFAULT,
+                                    testOriginMeta, isCanceled));
+      ASSERT_NO_FATAL_FAILURE(CheckUsageEqualTo(usageNow, initialDbUsage));
+
+      // Create a new file
+      TEST_TRY_UNWRAP(const EntryId rootId, data::GetRootHandle(testOrigin));
+      FileSystemChildMetadata fileData(rootId, GetTestFileName());
+
+      EntryId testFileId;
+      ASSERT_NO_FATAL_FAILURE(CreateNewEmptyFile(dbm, fileData, testFileId));
+
+      // After a new file has been created (only in the database),
+      // * database size has increased
+      // * GetUsageForOrigin and InitOrigin should agree
+      const auto expectedUse = initialDbUsage + 2 * sPage;
+
+      TEST_TRY_UNWRAP(usageNow, quotaClient->GetUsageForOrigin(
+                                    quota::PERSISTENCE_TYPE_DEFAULT,
+                                    testOriginMeta, isCanceled));
+      ASSERT_NO_FATAL_FAILURE(CheckUsageEqualTo(usageNow, expectedUse));
+
+      TEST_TRY_UNWRAP(usageNow,
+                      quotaClient->InitOrigin(quota::PERSISTENCE_TYPE_DEFAULT,
+                                              testOriginMeta, isCanceled));
+      ASSERT_NO_FATAL_FAILURE(CheckUsageEqualTo(usageNow, expectedUse));
+    };
+
+    RefPtr<mozilla::dom::quota::Client> quotaClient = fs::CreateQuotaClient();
+    ASSERT_TRUE(quotaClient);
+
+    // For uninitialized database, file usage is nothing
+    auto checkTask =
+        [&isCanceled](const RefPtr<mozilla::dom::quota::Client>& quotaClient) {
+          TEST_TRY_UNWRAP(quota::UsageInfo usageNow,
+                          quotaClient->GetUsageForOrigin(
+                              quota::PERSISTENCE_TYPE_DEFAULT,
+                              GetTestQuotaOriginMetadata(), isCanceled));
+
+          ASSERT_TRUE(usageNow.DatabaseUsage().isNothing());
+          EXPECT_TRUE(usageNow.FileUsage().isNothing());
+        };
+
+    PerformOnIOThread(std::move(checkTask),
+                      RefPtr<mozilla::dom::quota::Client>{quotaClient});
+
+    // Initialize database
+    Registered<data::FileSystemDataManager> rdm;
+    ASSERT_NO_FATAL_FAILURE(CreateRegisteredDataManager(rdm));
+
+    // Run tests with an initialized database
+    PerformOnIOThread(std::move(ioTask), std::move(quotaClient),
+                      rdm->MutableDatabaseManagerPtr());
+  };
+
+  PerformOnBackgroundThread(std::move(backgroundTask));
+}
+
+TEST_F(TestFileSystemQuotaClient, WritesToFilesShouldIncreaseUsage) {
+  auto backgroundTask = []() {
+    mozilla::Atomic<bool> isCanceled{false};
+    auto ioTask = [&isCanceled](
+                      const RefPtr<mozilla::dom::quota::Client>& quotaClient,
+                      data::FileSystemDatabaseManager* dbm) {
+      const quota::OriginMetadata& testOriginMeta =
+          GetTestQuotaOriginMetadata();
+      const Origin& testOrigin = testOriginMeta.mOrigin;
+
+      TEST_TRY_UNWRAP(const EntryId rootId, data::GetRootHandle(testOrigin));
+      FileSystemChildMetadata fileData(rootId, GetTestFileName());
+
+      EntryId testFileId;
+      ASSERT_NO_FATAL_FAILURE(CreateNewEmptyFile(dbm, fileData, testFileId));
+      // const auto testFileDbUsage = usageNow.DatabaseUsage().value();
+
+      TEST_TRY_UNWRAP(
+          quota::UsageInfo usageNow,
+          quotaClient->GetUsageForOrigin(quota::PERSISTENCE_TYPE_DEFAULT,
+                                         testOriginMeta, isCanceled));
+      ASSERT_TRUE(usageNow.DatabaseUsage().isSome());
+      const auto testFileDbUsage = usageNow.DatabaseUsage().value();
+
+      TEST_TRY_UNWRAP(usageNow,
+                      quotaClient->InitOrigin(quota::PERSISTENCE_TYPE_DEFAULT,
+                                              testOriginMeta, isCanceled));
+      ASSERT_NO_FATAL_FAILURE(CheckUsageEqualTo(usageNow, testFileDbUsage));
+
+      // Fill the file with some content
+      const nsCString& testData = GetTestData();
+
+      ASSERT_NO_FATAL_FAILURE(WriteDataToFile(dbm, testFileId, testData));
+
+      // In this test we don't lock the file -> no rescan is expected
+      // and InitOrigin should return the previous value
+      TEST_TRY_UNWRAP(usageNow,
+                      quotaClient->InitOrigin(quota::PERSISTENCE_TYPE_DEFAULT,
+                                              testOriginMeta, isCanceled));
+      ASSERT_NO_FATAL_FAILURE(CheckUsageEqualTo(usageNow, testFileDbUsage));
+
+      // When data manager unlocks the file, it should call update
+      // but in this test we call it directly
+      ASSERT_NSEQ(NS_OK, dbm->UpdateUsage(FileId(testFileId)));
+
+      const auto expectedTotalUsage = testFileDbUsage + testData.Length();
+
+      // Disk usage should have increased after writing
+      TEST_TRY_UNWRAP(usageNow,
+                      quotaClient->InitOrigin(quota::PERSISTENCE_TYPE_DEFAULT,
+                                              testOriginMeta, isCanceled));
+      ASSERT_NO_FATAL_FAILURE(CheckUsageEqualTo(usageNow, expectedTotalUsage));
+
+      // The usage values should now agree
+      TEST_TRY_UNWRAP(usageNow, quotaClient->GetUsageForOrigin(
+                                    quota::PERSISTENCE_TYPE_DEFAULT,
+                                    testOriginMeta, isCanceled));
+      ASSERT_NO_FATAL_FAILURE(CheckUsageEqualTo(usageNow, expectedTotalUsage));
+    };
+
+    RefPtr<mozilla::dom::quota::Client> quotaClient = fs::CreateQuotaClient();
+    ASSERT_TRUE(quotaClient);
+
+    // Initialize database
+    Registered<data::FileSystemDataManager> rdm;
+    ASSERT_NO_FATAL_FAILURE(CreateRegisteredDataManager(rdm));
+
+    // Run tests with an initialized database
+    PerformOnIOThread(std::move(ioTask), std::move(quotaClient),
+                      rdm->MutableDatabaseManagerPtr());
+  };
+
+  PerformOnBackgroundThread(std::move(backgroundTask));
+}
+
+TEST_F(TestFileSystemQuotaClient, TrackedFilesOnInitOriginShouldCauseRescan) {
+  auto backgroundTask = []() {
+    mozilla::Atomic<bool> isCanceled{false};
+    EntryId* testFileId = new EntryId();
+    auto cleanupFileId = MakeScopeExit([&testFileId] { delete testFileId; });
+
+    auto fileCreation = [&testFileId](data::FileSystemDatabaseManager* dbm) {
+      const Origin& testOrigin = GetTestQuotaOriginMetadata().mOrigin;
+
+      TEST_TRY_UNWRAP(const EntryId rootId, data::GetRootHandle(testOrigin));
+      FileSystemChildMetadata fileData(rootId, GetTestFileName());
+
+      EntryId someId;
+      ASSERT_NO_FATAL_FAILURE(CreateNewEmptyFile(dbm, fileData, someId));
+      testFileId->Append(someId);
+    };
+
+    auto writingToFile =
+        [&isCanceled, testFileId](
+            const RefPtr<mozilla::dom::quota::Client>& quotaClient,
+            data::FileSystemDatabaseManager* dbm) {
+          const quota::OriginMetadata& testOriginMeta =
+              GetTestQuotaOriginMetadata();
+          TEST_TRY_UNWRAP(
+              quota::UsageInfo usageNow,
+              quotaClient->GetUsageForOrigin(quota::PERSISTENCE_TYPE_DEFAULT,
+                                             testOriginMeta, isCanceled));
+          ASSERT_TRUE(usageNow.DatabaseUsage().isSome());
+          const auto testFileDbUsage = usageNow.DatabaseUsage().value();
+
+          // Fill the file with some content
+          const auto& testData = GetTestData();
+          const auto expectedTotalUsage = testFileDbUsage + testData.Length();
+
+          ASSERT_NO_FATAL_FAILURE(WriteDataToFile(dbm, *testFileId, testData));
+
+          // We don't call update now - because the file is tracked and
+          // InitOrigin should perform a rescan
+          TEST_TRY_UNWRAP(
+              usageNow, quotaClient->InitOrigin(quota::PERSISTENCE_TYPE_DEFAULT,
+                                                testOriginMeta, isCanceled));
+          ASSERT_NO_FATAL_FAILURE(
+              CheckUsageEqualTo(usageNow, expectedTotalUsage));
+
+          // As always, the cached and scanned values should agree
+          TEST_TRY_UNWRAP(usageNow, quotaClient->GetUsageForOrigin(
+                                        quota::PERSISTENCE_TYPE_DEFAULT,
+                                        testOriginMeta, isCanceled));
+          ASSERT_NO_FATAL_FAILURE(
+              CheckUsageEqualTo(usageNow, expectedTotalUsage));
+        };
+
+    RefPtr<mozilla::dom::quota::Client> quotaClient = fs::CreateQuotaClient();
+    ASSERT_TRUE(quotaClient);
+
+    // Initialize database
+    Registered<data::FileSystemDataManager> rdm;
+    ASSERT_NO_FATAL_FAILURE(CreateRegisteredDataManager(rdm));
+
+    PerformOnIOThread(std::move(fileCreation),
+                      rdm->MutableDatabaseManagerPtr());
+
+    // This should force a rescan
+    TEST_TRY_UNWRAP(FileId fileId, rdm->LockExclusive(*testFileId));
+    ASSERT_FALSE(fileId.IsEmpty());
+    PerformOnIOThread(std::move(writingToFile), std::move(quotaClient),
+                      rdm->MutableDatabaseManagerPtr());
+  };
+
+  PerformOnBackgroundThread(std::move(backgroundTask));
+}
+
+TEST_F(TestFileSystemQuotaClient, RemovingFileShouldDecreaseUsage) {
+  auto backgroundTask = []() {
+    mozilla::Atomic<bool> isCanceled{false};
+    auto ioTask = [&isCanceled](
+                      const RefPtr<mozilla::dom::quota::Client>& quotaClient,
+                      data::FileSystemDatabaseManager* dbm) {
+      const quota::OriginMetadata& testOriginMeta =
+          GetTestQuotaOriginMetadata();
+      const Origin& testOrigin = testOriginMeta.mOrigin;
+
+      TEST_TRY_UNWRAP(const EntryId rootId, data::GetRootHandle(testOrigin));
+      FileSystemChildMetadata fileData(rootId, GetTestFileName());
+
+      EntryId testFileId;
+      ASSERT_NO_FATAL_FAILURE(CreateNewEmptyFile(dbm, fileData, testFileId));
+      TEST_TRY_UNWRAP(quota::UsageInfo usageNow,
+                      quotaClient->InitOrigin(quota::PERSISTENCE_TYPE_DEFAULT,
+                                              testOriginMeta, isCanceled));
+      ASSERT_TRUE(usageNow.DatabaseUsage().isSome());
+      const auto testFileDbUsage = usageNow.DatabaseUsage().value();
+
+      // Fill the file with some content
+      const nsCString& testData = GetTestData();
+      const auto expectedTotalUsage = testFileDbUsage + testData.Length();
+
+      ASSERT_NO_FATAL_FAILURE(WriteDataToFile(dbm, testFileId, testData));
+
+      // Currently, usage is expected to be updated on unlock by data manager
+      // but here UpdateUsage() is called directly
+      ASSERT_NSEQ(NS_OK, dbm->UpdateUsage(FileId(testFileId)));
+
+      // At least some file disk usage should have appeared after unlocking
+      TEST_TRY_UNWRAP(usageNow, quotaClient->GetUsageForOrigin(
+                                    quota::PERSISTENCE_TYPE_DEFAULT,
+                                    testOriginMeta, isCanceled));
+      ASSERT_NO_FATAL_FAILURE(CheckUsageEqualTo(usageNow, expectedTotalUsage));
+
+      TEST_TRY_UNWRAP(bool wasRemoved,
+                      dbm->RemoveFile({rootId, GetTestFileName()}));
+      ASSERT_TRUE(wasRemoved);
+
+      // Removes cascade and usage table should be up to date immediately
+      TEST_TRY_UNWRAP(usageNow,
+                      quotaClient->InitOrigin(quota::PERSISTENCE_TYPE_DEFAULT,
+                                              testOriginMeta, isCanceled));
+      ASSERT_NO_FATAL_FAILURE(CheckUsageEqualTo(usageNow, testFileDbUsage));
+
+      // GetUsageForOrigin should agree
+      TEST_TRY_UNWRAP(usageNow, quotaClient->GetUsageForOrigin(
+                                    quota::PERSISTENCE_TYPE_DEFAULT,
+                                    testOriginMeta, isCanceled));
+
+      ASSERT_NO_FATAL_FAILURE(CheckUsageEqualTo(usageNow, testFileDbUsage));
+    };
+
+    RefPtr<mozilla::dom::quota::Client> quotaClient = fs::CreateQuotaClient();
+    ASSERT_TRUE(quotaClient);
+
+    // Initialize database
+    Registered<data::FileSystemDataManager> rdm;
+    ASSERT_NO_FATAL_FAILURE(CreateRegisteredDataManager(rdm));
+
+    // Run tests with an initialized database
+    PerformOnIOThread(std::move(ioTask), std::move(quotaClient),
+                      rdm->MutableDatabaseManagerPtr());
+  };
+
+  PerformOnBackgroundThread(std::move(backgroundTask));
+}
+
+}  // namespace mozilla::dom::fs::test
diff --git a/dom/fs/test/gtest/parent/datamodel/TestFileSystemDataManager.cpp b/dom/fs/test/gtest/parent/datamodel/TestFileSystemDataManager.cpp
new file mode 100644
index 0000000000..484def797f
--- /dev/null
+++ b/dom/fs/test/gtest/parent/datamodel/TestFileSystemDataManager.cpp
@@ -0,0 +1,185 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "FileSystemDataManager.h"
+#include "TestHelpers.h"
+#include "mozilla/MozPromise.h"
+#include "mozilla/SpinEventLoopUntil.h"
+#include "mozilla/dom/quota/ForwardDecls.h"
+#include "mozilla/dom/quota/test/QuotaManagerDependencyFixture.h"
+
+namespace mozilla::dom::fs::test {
+
+class TestFileSystemDataManager
+    : public quota::test::QuotaManagerDependencyFixture {
+ public:
+  static void SetUpTestCase() { ASSERT_NO_FATAL_FAILURE(InitializeFixture()); }
+
+  static void TearDownTestCase() {
+    EXPECT_NO_FATAL_FAILURE(ClearStoragesForOrigin(GetTestOriginMetadata()));
+    ASSERT_NO_FATAL_FAILURE(ShutdownFixture());
+  }
+};
+
+TEST_F(TestFileSystemDataManager, GetOrCreateFileSystemDataManager) {
+  auto backgroundTask = []() {
+    bool done = false;
+
+    data::FileSystemDataManager::GetOrCreateFileSystemDataManager(
+        GetTestOriginMetadata())
+        ->Then(
+            GetCurrentSerialEventTarget(), __func__,
+            [](Registered<data::FileSystemDataManager> registeredDataManager) {
+              RefPtr<data::FileSystemDataManager> dataManager =
+                  registeredDataManager.get();
+
+              registeredDataManager = nullptr;
+
+              return dataManager->OnClose();
+            },
+            [](nsresult rejectValue) {
+              return BoolPromise::CreateAndReject(rejectValue, __func__);
+            })
+        ->Then(
+            GetCurrentSerialEventTarget(), __func__,
+            [&done](const BoolPromise::ResolveOrRejectValue&) { done = true; });
+
+    SpinEventLoopUntil("Promise is fulfilled"_ns, [&done]() { return done; });
+  };
+
+  PerformOnBackgroundThread(std::move(backgroundTask));
+}
+
+TEST_F(TestFileSystemDataManager,
+       GetOrCreateFileSystemDataManager_PendingOpen) {
+  auto backgroundTask = []() {
+    Registered<data::FileSystemDataManager> rdm1;
+
+    Registered<data::FileSystemDataManager> rdm2;
+
+    {
+      bool done1 = false;
+
+      data::FileSystemDataManager::GetOrCreateFileSystemDataManager(
+          GetTestOriginMetadata())
+          ->Then(
+              GetCurrentSerialEventTarget(), __func__,
+              [&rdm1, &done1](Registered<data::FileSystemDataManager>
+                                  registeredDataManager) {
+                ASSERT_TRUE(registeredDataManager->IsOpen());
+
+                rdm1 = std::move(registeredDataManager);
+
+                done1 = true;
+              },
+              [&done1](nsresult rejectValue) { done1 = true; });
+
+      bool done2 = false;
+
+      data::FileSystemDataManager::GetOrCreateFileSystemDataManager(
+          GetTestOriginMetadata())
+          ->Then(
+              GetCurrentSerialEventTarget(), __func__,
+              [&rdm2, &done2](Registered<data::FileSystemDataManager>
+                                  registeredDataManager) {
+                ASSERT_TRUE(registeredDataManager->IsOpen());
+
+                rdm2 = std::move(registeredDataManager);
+
+                done2 = true;
+              },
+              [&done2](nsresult rejectValue) { done2 = true; });
+
+      SpinEventLoopUntil("Promise is fulfilled"_ns,
+                         [&done1, &done2]() { return done1 && done2; });
+    }
+
+    RefPtr<data::FileSystemDataManager> dm1 = rdm1.unwrap();
+
+    RefPtr<data::FileSystemDataManager> dm2 = rdm2.unwrap();
+
+    {
+      bool done1 = false;
+
+      dm1->OnClose()->Then(
+          GetCurrentSerialEventTarget(), __func__,
+          [&done1](const BoolPromise::ResolveOrRejectValue&) { done1 = true; });
+
+      bool done2 = false;
+
+      dm2->OnClose()->Then(
+          GetCurrentSerialEventTarget(), __func__,
+          [&done2](const BoolPromise::ResolveOrRejectValue&) { done2 = true; });
+
+      SpinEventLoopUntil("Promise is fulfilled"_ns,
+                         [&done1, &done2]() { return done1 && done2; });
+    }
+  };
+
+  PerformOnBackgroundThread(std::move(backgroundTask));
+}
+
+TEST_F(TestFileSystemDataManager,
+       GetOrCreateFileSystemDataManager_PendingClose) {
+  auto backgroundTask = []() {
+    Registered<data::FileSystemDataManager> rdm;
+
+    {
+      bool done = false;
+
+      data::FileSystemDataManager::GetOrCreateFileSystemDataManager(
+          GetTestOriginMetadata())
+          ->Then(
+              GetCurrentSerialEventTarget(), __func__,
+              [&rdm, &done](Registered<data::FileSystemDataManager>
+                                registeredDataManager) {
+                ASSERT_TRUE(registeredDataManager->IsOpen());
+
+                rdm = std::move(registeredDataManager);
+
+                done = true;
+              },
+              [&done](nsresult rejectValue) { done = true; });
+
+      SpinEventLoopUntil("Promise is fulfilled"_ns, [&done]() { return done; });
+    }
+
+    RefPtr<data::FileSystemDataManager> dm = rdm.unwrap();
+
+    Unused << dm;
+
+    {
+      bool done = false;
+
+      data::FileSystemDataManager::GetOrCreateFileSystemDataManager(
+          GetTestOriginMetadata())
+          ->Then(
+              GetCurrentSerialEventTarget(), __func__,
+              [](Registered<data::FileSystemDataManager>
+                     registeredDataManager) {
+                RefPtr<data::FileSystemDataManager> dataManager =
+                    registeredDataManager.get();
+
+                registeredDataManager = nullptr;
+
+                return dataManager->OnClose();
+              },
+              [](nsresult rejectValue) {
+                return BoolPromise::CreateAndReject(rejectValue, __func__);
+              })
+          ->Then(GetCurrentSerialEventTarget(), __func__,
+                 [&done](const BoolPromise::ResolveOrRejectValue&) {
+                   done = true;
+                 });
+
+      SpinEventLoopUntil("Promise is fulfilled"_ns, [&done]() { return done; });
+    }
+  };
+
+  PerformOnBackgroundThread(std::move(backgroundTask));
+}
+
+}  // namespace mozilla::dom::fs::test
diff --git a/dom/fs/test/gtest/parent/datamodel/TestFileSystemDataManagerVersions.cpp b/dom/fs/test/gtest/parent/datamodel/TestFileSystemDataManagerVersions.cpp
new file mode 100644
index 0000000000..9782e534e9
--- /dev/null
+++ b/dom/fs/test/gtest/parent/datamodel/TestFileSystemDataManagerVersions.cpp
@@ -0,0 +1,1059 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <algorithm>
+
+#include "ErrorList.h"
+#include "FileSystemDataManager.h"
+#include "FileSystemDatabaseManagerVersion001.h"
+#include "FileSystemDatabaseManagerVersion002.h"
+#include "FileSystemFileManager.h"
+#include "FileSystemHashSource.h"
+#include "ResultStatement.h"
+#include "SchemaVersion001.h"
+#include "SchemaVersion002.h"
+#include "TestHelpers.h"
+#include "gtest/gtest.h"
+#include "mozIStorageService.h"
+#include "mozStorageCID.h"
+#include "mozStorageHelper.h"
+#include "mozilla/Array.h"
+#include "mozilla/ErrorNames.h"
+#include "mozilla/Result.h"
+#include "mozilla/dom/FileSystemTypes.h"
+#include "mozilla/dom/PFileSystemManager.h"
+#include "mozilla/dom/quota/CommonMetadata.h"
+#include "mozilla/dom/quota/test/QuotaManagerDependencyFixture.h"
+#include "nsContentUtils.h"
+#include "nsIFile.h"
+#include "nsLiteralString.h"
+#include "nsNetCID.h"
+#include "nsReadableUtils.h"
+#include "nsString.h"
+#include "nsStringFwd.h"
+#include "nsTArray.h"
+#include "nsTHashSet.h"
+
+namespace mozilla::dom::fs::test {
+
+using data::FileSystemDatabaseManagerVersion001;
+using data::FileSystemDatabaseManagerVersion002;
+using data::FileSystemFileManager;
+
+quota::OriginMetadata GetOriginMetadataSample() {
+  return quota::OriginMetadata{""_ns,
+                               "firefox.com"_ns,
+                               "http://firefox.com"_ns,
+                               "http://firefox.com"_ns,
+                               /* aIsPrivate */ false,
+                               quota::PERSISTENCE_TYPE_DEFAULT};
+}
+
+class TestFileSystemDatabaseManagerVersionsBase
+    : public quota::test::QuotaManagerDependencyFixture {
+ public:
+  void SetUp() override { ASSERT_NO_FATAL_FAILURE(InitializeFixture()); }
+
+  void TearDown() override {
+    EXPECT_NO_FATAL_FAILURE(ClearStoragesForOrigin(GetOriginMetadataSample()));
+    ASSERT_NO_FATAL_FAILURE(ShutdownFixture());
+  }
+};
+
+class TestFileSystemDatabaseManagerVersions
+    : public TestFileSystemDatabaseManagerVersionsBase,
+      public ::testing::WithParamInterface<DatabaseVersion> {
+ public:
+  static void AssertEntryIdMoved(const EntryId& aOriginal,
+                                 const EntryId& aMoved) {
+    switch (sVersion) {
+      case 1: {
+        ASSERT_EQ(aOriginal, aMoved);
+        break;
+      }
+      case 2: {
+        ASSERT_NE(aOriginal, aMoved);
+        break;
+      }
+      default: {
+        ASSERT_FALSE(false)
+        << "Unknown database version";
+      }
+    }
+  }
+
+  static void AssertEntryIdCollision(const EntryId& aOriginal,
+                                     const EntryId& aMoved) {
+    switch (sVersion) {
+      case 1: {
+        // We generated a new entryId
+        ASSERT_NE(aOriginal, aMoved);
+        break;
+      }
+      case 2: {
+        // We get the same entryId for the same input
+        ASSERT_EQ(aOriginal, aMoved);
+        break;
+      }
+      default: {
+        ASSERT_FALSE(false)
+        << "Unknown database version";
+      }
+    }
+  }
+
+  static DatabaseVersion sVersion;
+};
+
+// This is a minimal mock  to allow us to safely call the lock methods
+// while avoiding assertions
+class MockFileSystemDataManager final : public data::FileSystemDataManager {
+ public:
+  MockFileSystemDataManager(const quota::OriginMetadata& aOriginMetadata,
+                            MovingNotNull<nsCOMPtr<nsIEventTarget>> aIOTarget,
+                            MovingNotNull<RefPtr<TaskQueue>> aIOTaskQueue)
+      : FileSystemDataManager(aOriginMetadata, nullptr, std::move(aIOTarget),
+                              std::move(aIOTaskQueue)) {}
+
+  void SetDatabaseManager(data::FileSystemDatabaseManager* aDatabaseManager) {
+    mDatabaseManager =
+        UniquePtr<data::FileSystemDatabaseManager>(aDatabaseManager);
+  }
+
+  virtual ~MockFileSystemDataManager() {
+    mDatabaseManager->Close();
+    mDatabaseManager = nullptr;
+
+    // Need to avoid assertions
+    mState = State::Closed;
+  }
+};
+
+static void MakeDatabaseManagerVersions(
+    const DatabaseVersion aVersion,
+    RefPtr<MockFileSystemDataManager>& aDataManager,
+    FileSystemDatabaseManagerVersion001*& aDatabaseManager) {
+  TEST_TRY_UNWRAP(auto storageService,
+                  MOZ_TO_RESULT_GET_TYPED(nsCOMPtr<mozIStorageService>,
+                                          MOZ_SELECT_OVERLOAD(do_GetService),
+                                          MOZ_STORAGE_SERVICE_CONTRACTID));
+
+  const auto flags = mozIStorageService::CONNECTION_DEFAULT;
+  ResultConnection connection;
+
+  nsresult rv = storageService->OpenSpecialDatabase(kMozStorageMemoryStorageKey,
+                                                    VoidCString(), flags,
+                                                    getter_AddRefs(connection));
+  ASSERT_NSEQ(NS_OK, rv);
+
+  auto fmRes = FileSystemFileManager::CreateFileSystemFileManager(
+      GetOriginMetadataSample());
+  ASSERT_FALSE(fmRes.isErr());
+
+  const Origin& testOrigin = GetTestOrigin();
+
+  if (1 == aVersion) {
+    TEST_TRY_UNWRAP(
+        TestFileSystemDatabaseManagerVersions::sVersion,
+        SchemaVersion001::InitializeConnection(connection, testOrigin));
+  } else {
+    ASSERT_EQ(2, aVersion);
+
+    TEST_TRY_UNWRAP(TestFileSystemDatabaseManagerVersions::sVersion,
+                    SchemaVersion002::InitializeConnection(
+                        connection, *fmRes.inspect(), testOrigin));
+  }
+  ASSERT_NE(0, TestFileSystemDatabaseManagerVersions::sVersion);
+
+  TEST_TRY_UNWRAP(EntryId rootId, data::GetRootHandle(GetTestOrigin()));
+
+  QM_TRY_UNWRAP(auto streamTransportService,
+                MOZ_TO_RESULT_GET_TYPED(nsCOMPtr<nsIEventTarget>,
+                                        MOZ_SELECT_OVERLOAD(do_GetService),
+                                        NS_STREAMTRANSPORTSERVICE_CONTRACTID),
+                QM_VOID);
+
+  quota::OriginMetadata originMetadata = GetOriginMetadataSample();
+
+  nsCString taskQueueName("OPFS "_ns + originMetadata.mOrigin);
+
+  RefPtr<TaskQueue> ioTaskQueue =
+      TaskQueue::Create(do_AddRef(streamTransportService), taskQueueName.get());
+
+  aDataManager = MakeRefPtr<MockFileSystemDataManager>(
+      originMetadata, WrapMovingNotNull(streamTransportService),
+      WrapMovingNotNull(ioTaskQueue));
+
+  if (1 == aVersion) {
+    aDatabaseManager = new FileSystemDatabaseManagerVersion001(
+        aDataManager, std::move(connection), fmRes.unwrap(), rootId);
+  } else {
+    ASSERT_EQ(2, aVersion);
+
+    aDatabaseManager = new FileSystemDatabaseManagerVersion002(
+        aDataManager, std::move(connection), fmRes.unwrap(), rootId);
+  }
+
+  aDataManager->SetDatabaseManager(aDatabaseManager);
+}
+
+DatabaseVersion TestFileSystemDatabaseManagerVersions::sVersion = 0;
+
+TEST_P(TestFileSystemDatabaseManagerVersions,
+       smokeTestCreateRemoveDirectories) {
+  const DatabaseVersion version = GetParam();
+
+  auto ioTask = [version]() {
+    nsresult rv = NS_OK;
+    // Ensure that FileSystemDataManager lives for the lifetime of the test
+    RefPtr<MockFileSystemDataManager> dataManager;
+    FileSystemDatabaseManagerVersion001* dm = nullptr;
+    ASSERT_NO_FATAL_FAILURE(
+        MakeDatabaseManagerVersions(version, dataManager, dm));
+    ASSERT_TRUE(dm);
+    // if any of these exit early, we have to close
+    auto autoClose = MakeScopeExit([dm] { dm->Close(); });
+
+    TEST_TRY_UNWRAP(EntryId rootId, data::GetRootHandle(GetTestOrigin()));
+
+    FileSystemChildMetadata firstChildMeta(rootId, u"First"_ns);
+    TEST_TRY_UNWRAP_ERR(
+        rv, dm->GetOrCreateDirectory(firstChildMeta, /* create */ false));
+    ASSERT_NSEQ(NS_ERROR_DOM_NOT_FOUND_ERR, rv);
+
+    TEST_TRY_UNWRAP(EntryId firstChild, dm->GetOrCreateDirectory(
+                                            firstChildMeta, /* create */ true));
+
+    int32_t dbVersion = 0;
+    TEST_TRY_UNWRAP(FileSystemDirectoryListing entries,
+                    dm->GetDirectoryEntries(rootId, dbVersion));
+    ASSERT_EQ(1u, entries.directories().Length());
+    ASSERT_EQ(0u, entries.files().Length());
+
+    const auto& firstItemRef = entries.directories()[0];
+    ASSERT_TRUE(u"First"_ns == firstItemRef.entryName())
+    << firstItemRef.entryName();
+    ASSERT_EQ(firstChild, firstItemRef.entryId());
+
+    TEST_TRY_UNWRAP(
+        EntryId firstChildClone,
+        dm->GetOrCreateDirectory(firstChildMeta, /* create */ true));
+    ASSERT_EQ(firstChild, firstChildClone);
+
+    FileSystemChildMetadata secondChildMeta(firstChild, u"Second"_ns);
+    TEST_TRY_UNWRAP(
+        EntryId secondChild,
+        dm->GetOrCreateDirectory(secondChildMeta, /* create */ true));
+
+    FileSystemEntryPair shortPair(firstChild, secondChild);
+    TEST_TRY_UNWRAP(Path shortPath, dm->Resolve(shortPair));
+    ASSERT_EQ(1u, shortPath.Length());
+    ASSERT_EQ(u"Second"_ns, shortPath[0]);
+
+    FileSystemEntryPair longPair(rootId, secondChild);
+    TEST_TRY_UNWRAP(Path longPath, dm->Resolve(longPair));
+    ASSERT_EQ(2u, longPath.Length());
+    ASSERT_EQ(u"First"_ns, longPath[0]);
+    ASSERT_EQ(u"Second"_ns, longPath[1]);
+
+    FileSystemEntryPair wrongPair(secondChild, rootId);
+    TEST_TRY_UNWRAP(Path emptyPath, dm->Resolve(wrongPair));
+    ASSERT_TRUE(emptyPath.IsEmpty());
+
+    PageNumber page = 0;
+    TEST_TRY_UNWRAP(FileSystemDirectoryListing fEntries,
+                    dm->GetDirectoryEntries(firstChild, page));
+    ASSERT_EQ(1u, fEntries.directories().Length());
+    ASSERT_EQ(0u, fEntries.files().Length());
+
+    const auto& secItemRef = fEntries.directories()[0];
+    ASSERT_TRUE(u"Second"_ns == secItemRef.entryName())
+    << secItemRef.entryName();
+    ASSERT_EQ(secondChild, secItemRef.entryId());
+
+    TEST_TRY_UNWRAP_ERR(
+        rv, dm->RemoveDirectory(firstChildMeta, /* recursive */ false));
+    ASSERT_NSEQ(NS_ERROR_DOM_INVALID_MODIFICATION_ERR, rv);
+
+    TEST_TRY_UNWRAP(bool isDeleted,
+                    dm->RemoveDirectory(firstChildMeta, /* recursive */ true));
+    ASSERT_TRUE(isDeleted);
+
+    FileSystemChildMetadata thirdChildMeta(secondChild, u"Second"_ns);
+    TEST_TRY_UNWRAP_ERR(
+        rv, dm->GetOrCreateDirectory(thirdChildMeta, /* create */ true));
+    ASSERT_NSEQ(NS_ERROR_STORAGE_CONSTRAINT, rv);  // Is this a good error?
+
+    dm->Close();
+  };
+
+  PerformOnIOThread(std::move(ioTask));
+}
+
+TEST_P(TestFileSystemDatabaseManagerVersions, smokeTestCreateRemoveFiles) {
+  const DatabaseVersion version = GetParam();
+
+  auto ioTask = [version]() {
+    nsresult rv = NS_OK;
+    // Ensure that FileSystemDataManager lives for the lifetime of the test
+    RefPtr<MockFileSystemDataManager> datamanager;
+    FileSystemDatabaseManagerVersion001* dm = nullptr;
+    ASSERT_NO_FATAL_FAILURE(
+        MakeDatabaseManagerVersions(version, datamanager, dm));
+
+    TEST_TRY_UNWRAP(EntryId rootId, data::GetRootHandle(GetTestOrigin()));
+
+    FileSystemChildMetadata firstChildMeta(rootId, u"First"_ns);
+    // If creating is not allowed, getting a file from empty root fails
+    TEST_TRY_UNWRAP_ERR(
+        rv, dm->GetOrCreateFile(firstChildMeta, /* create */ false));
+    ASSERT_NSEQ(NS_ERROR_DOM_NOT_FOUND_ERR, rv);
+
+    // Creating a file under empty root succeeds
+    TEST_TRY_UNWRAP(EntryId firstChild,
+                    dm->GetOrCreateFile(firstChildMeta, /* create */ true));
+
+    // Second time, the same file is returned
+    TEST_TRY_UNWRAP(EntryId firstChildClone,
+                    dm->GetOrCreateFile(firstChildMeta, /* create */ true));
+    ASSERT_EQ(firstChild, firstChildClone);
+
+    // Directory listing returns the created file
+    PageNumber page = 0;
+    TEST_TRY_UNWRAP(FileSystemDirectoryListing entries,
+                    dm->GetDirectoryEntries(rootId, page));
+    ASSERT_EQ(0u, entries.directories().Length());
+    ASSERT_EQ(1u, entries.files().Length());
+
+    auto& firstItemRef = entries.files()[0];
+    ASSERT_TRUE(u"First"_ns == firstItemRef.entryName())
+    << firstItemRef.entryName();
+    ASSERT_EQ(firstChild, firstItemRef.entryId());
+
+    FileId fileId = FileId(firstItemRef.entryId());  // Default
+
+    ContentType type;
+    TimeStamp lastModifiedMilliSeconds;
+    Path path;
+    nsCOMPtr<nsIFile> file;
+    rv = dm->GetFile(firstItemRef.entryId(), fileId, FileMode::EXCLUSIVE, type,
+                     lastModifiedMilliSeconds, path, file);
+    ASSERT_NSEQ(NS_OK, rv);
+
+    const int64_t nowMilliSeconds = PR_Now() / 1000;
+    ASSERT_GE(nowMilliSeconds, lastModifiedMilliSeconds);
+    const int64_t expectedMaxDelayMilliSeconds = 100;
+    const int64_t actualDelay = nowMilliSeconds - lastModifiedMilliSeconds;
+    ASSERT_LT(actualDelay, expectedMaxDelayMilliSeconds);
+
+    ASSERT_EQ(1u, path.Length());
+    ASSERT_STREQ(u"First"_ns, path[0]);
+
+    ASSERT_NE(nullptr, file);
+
+    // Getting the file entry as directory fails
+    TEST_TRY_UNWRAP_ERR(
+        rv, dm->GetOrCreateDirectory(firstChildMeta, /* create */ false));
+    ASSERT_NSEQ(NS_ERROR_DOM_TYPE_MISMATCH_ERR, rv);
+
+    // Getting or creating the file entry as directory also fails
+    TEST_TRY_UNWRAP_ERR(
+        rv, dm->GetOrCreateDirectory(firstChildMeta, /* create */ true));
+    ASSERT_NSEQ(NS_ERROR_DOM_TYPE_MISMATCH_ERR, rv);
+
+    // Creating a file with non existing parent hash fails
+
+    EntryId notAChildHash = "0123456789abcdef0123456789abcdef"_ns;
+    FileSystemChildMetadata notAChildMeta(notAChildHash, u"Dummy"_ns);
+    TEST_TRY_UNWRAP_ERR(rv,
+                        dm->GetOrCreateFile(notAChildMeta, /* create */ true));
+    ASSERT_NSEQ(NS_ERROR_STORAGE_CONSTRAINT, rv);  // Is this a good error?
+
+    // We create a directory under root
+    FileSystemChildMetadata secondChildMeta(rootId, u"Second"_ns);
+    TEST_TRY_UNWRAP(
+        EntryId secondChild,
+        dm->GetOrCreateDirectory(secondChildMeta, /* create */ true));
+
+    // The root should now contain the existing file and the new directory
+    TEST_TRY_UNWRAP(FileSystemDirectoryListing fEntries,
+                    dm->GetDirectoryEntries(rootId, page));
+    ASSERT_EQ(1u, fEntries.directories().Length());
+    ASSERT_EQ(1u, fEntries.files().Length());
+
+    const auto& secItemRef = fEntries.directories()[0];
+    ASSERT_TRUE(u"Second"_ns == secItemRef.entryName())
+    << secItemRef.entryName();
+    ASSERT_EQ(secondChild, secItemRef.entryId());
+
+    // Create a file under the new directory
+    FileSystemChildMetadata thirdChildMeta(secondChild, u"Third"_ns);
+    TEST_TRY_UNWRAP(EntryId thirdChild,
+                    dm->GetOrCreateFile(thirdChildMeta, /* create */ true));
+
+    FileSystemEntryPair entryPair(rootId, thirdChild);
+    TEST_TRY_UNWRAP(Path entryPath, dm->Resolve(entryPair));
+    ASSERT_EQ(2u, entryPath.Length());
+    ASSERT_EQ(u"Second"_ns, entryPath[0]);
+    ASSERT_EQ(u"Third"_ns, entryPath[1]);
+
+    // If recursion is not allowed, the non-empty new directory may not be
+    // removed
+    TEST_TRY_UNWRAP_ERR(
+        rv, dm->RemoveDirectory(secondChildMeta, /* recursive */ false));
+    ASSERT_NSEQ(NS_ERROR_DOM_INVALID_MODIFICATION_ERR, rv);
+
+    // If recursion is allowed, the new directory goes away.
+    TEST_TRY_UNWRAP(bool isDeleted,
+                    dm->RemoveDirectory(secondChildMeta, /* recursive */ true));
+    ASSERT_TRUE(isDeleted);
+
+    // The file under the removed directory is no longer accessible.
+    TEST_TRY_UNWRAP_ERR(rv,
+                        dm->GetOrCreateFile(thirdChildMeta, /* create */ true));
+    ASSERT_NSEQ(NS_ERROR_STORAGE_CONSTRAINT, rv);  // Is this a good error?
+
+    // The deletion is reflected by the root directory listing
+    TEST_TRY_UNWRAP(FileSystemDirectoryListing nEntries,
+                    dm->GetDirectoryEntries(rootId, 0));
+    ASSERT_EQ(0u, nEntries.directories().Length());
+    ASSERT_EQ(1u, nEntries.files().Length());
+
+    const auto& fileItemRef = nEntries.files()[0];
+    ASSERT_TRUE(u"First"_ns == fileItemRef.entryName())
+    << fileItemRef.entryName();
+    ASSERT_EQ(firstChild, fileItemRef.entryId());
+
+    dm->Close();
+  };
+
+  PerformOnIOThread(std::move(ioTask));
+}
+
+TEST_P(TestFileSystemDatabaseManagerVersions, smokeTestCreateMoveDirectories) {
+  const DatabaseVersion version = GetParam();
+
+  auto ioTask = [version]() {
+    // Ensure that FileSystemDataManager lives for the lifetime of the test
+    RefPtr<MockFileSystemDataManager> datamanager;
+    FileSystemDatabaseManagerVersion001* dm = nullptr;
+    ASSERT_NO_FATAL_FAILURE(
+        MakeDatabaseManagerVersions(version, datamanager, dm));
+    auto closeAtExit = MakeScopeExit([&dm]() { dm->Close(); });
+
+    TEST_TRY_UNWRAP(EntryId rootId, data::GetRootHandle(GetTestOrigin()));
+
+    FileSystemEntryMetadata rootMeta{rootId, u"root"_ns,
+                                     /* is directory */ true};
+
+    {
+      // Sanity check: no existing items should be found
+      TEST_TRY_UNWRAP(FileSystemDirectoryListing contents,
+                      dm->GetDirectoryEntries(rootId, /* page */ 0u));
+      ASSERT_TRUE(contents.directories().IsEmpty());
+      ASSERT_TRUE(contents.files().IsEmpty());
+    }
+
+    // Create subdirectory
+    FileSystemChildMetadata firstChildMeta(rootId, u"First"_ns);
+    TEST_TRY_UNWRAP(
+        EntryId firstChildDir,
+        dm->GetOrCreateDirectory(firstChildMeta, /* create */ true));
+
+    {
+      // Check that directory listing is as expected
+      TEST_TRY_UNWRAP(FileSystemDirectoryListing contents,
+                      dm->GetDirectoryEntries(rootId, /* page */ 0u));
+      ASSERT_TRUE(contents.files().IsEmpty());
+      ASSERT_EQ(1u, contents.directories().Length());
+      ASSERT_STREQ(firstChildMeta.childName(),
+                   contents.directories()[0].entryName());
+    }
+
+    {
+      // Try to move subdirectory to its current location
+      FileSystemEntryMetadata src{firstChildDir, firstChildMeta.childName(),
+                                  /* is directory */ true};
+      FileSystemChildMetadata dest{rootId, src.entryName()};
+      TEST_TRY_UNWRAP(EntryId moved, dm->MoveEntry(src, dest));
+      ASSERT_FALSE(moved.IsEmpty());
+      firstChildDir = moved;
+    }
+
+    {
+      // Try to move subdirectory under itself
+      FileSystemEntryMetadata src{firstChildDir, firstChildMeta.childName(),
+                                  /* is directory */ true};
+      FileSystemChildMetadata dest{src.entryId(), src.entryName()};
+      TEST_TRY_UNWRAP_ERR(nsresult rv, dm->MoveEntry(src, dest));
+      ASSERT_NSEQ(NS_ERROR_DOM_INVALID_MODIFICATION_ERR, rv);
+    }
+
+    {
+      // Try to move root under its subdirectory
+      FileSystemEntryMetadata src{rootId, rootMeta.entryName(),
+                                  /* is directory */ true};
+      FileSystemChildMetadata dest{firstChildDir, src.entryName()};
+      TEST_TRY_UNWRAP_ERR(nsresult rv, dm->MoveEntry(src, dest));
+      ASSERT_NSEQ(NS_ERROR_DOM_NOT_FOUND_ERR, rv);
+    }
+
+    // Create subsubdirectory
+    FileSystemChildMetadata firstChildDescendantMeta(firstChildDir,
+                                                     u"Descendant"_ns);
+    TEST_TRY_UNWRAP(EntryId firstChildDescendant,
+                    dm->GetOrCreateDirectory(firstChildDescendantMeta,
+                                             /* create */ true));
+
+    {
+      TEST_TRY_UNWRAP(FileSystemDirectoryListing contents,
+                      dm->GetDirectoryEntries(firstChildDir, /* page */ 0u));
+      ASSERT_TRUE(contents.files().IsEmpty());
+      ASSERT_EQ(1u, contents.directories().Length());
+      ASSERT_STREQ(firstChildDescendantMeta.childName(),
+                   contents.directories()[0].entryName());
+
+      TEST_TRY_UNWRAP(
+          Path subSubDirPath,
+          dm->Resolve({rootId, contents.directories()[0].entryId()}));
+      ASSERT_EQ(2u, subSubDirPath.Length());
+      ASSERT_STREQ(firstChildMeta.childName(), subSubDirPath[0]);
+      ASSERT_STREQ(firstChildDescendantMeta.childName(), subSubDirPath[1]);
+    }
+
+    {
+      // Try to move subsubdirectory to its current location
+      FileSystemEntryMetadata src{firstChildDescendant,
+                                  firstChildDescendantMeta.childName(),
+                                  /* is directory */ true};
+      FileSystemChildMetadata dest{firstChildDir, src.entryName()};
+      TEST_TRY_UNWRAP(EntryId moved, dm->MoveEntry(src, dest));
+      ASSERT_FALSE(moved.IsEmpty());
+      firstChildDescendant = moved;
+    }
+
+    {
+      // Try to move subsubdirectory under itself
+      FileSystemEntryMetadata src{firstChildDescendant,
+                                  firstChildDescendantMeta.childName(),
+                                  /* is directory */ true};
+      FileSystemChildMetadata dest{src.entryId(), src.entryName()};
+      TEST_TRY_UNWRAP_ERR(nsresult rv, dm->MoveEntry(src, dest));
+      ASSERT_NSEQ(NS_ERROR_DOM_INVALID_MODIFICATION_ERR, rv);
+    }
+
+    {
+      // Try to move subdirectory under its descendant
+      FileSystemEntryMetadata src{firstChildDir, firstChildMeta.childName(),
+                                  /* is directory */ true};
+      FileSystemChildMetadata dest{firstChildDescendant, src.entryName()};
+      TEST_TRY_UNWRAP_ERR(nsresult rv, dm->MoveEntry(src, dest));
+      ASSERT_NSEQ(NS_ERROR_DOM_INVALID_MODIFICATION_ERR, rv);
+    }
+
+    {
+      // Try to move root under its subsubdirectory
+      FileSystemEntryMetadata src{rootId, rootMeta.entryName(),
+                                  /* is directory */ true};
+      FileSystemChildMetadata dest{firstChildDescendant, src.entryName()};
+      TEST_TRY_UNWRAP_ERR(nsresult rv, dm->MoveEntry(src, dest));
+      ASSERT_NSEQ(NS_ERROR_DOM_NOT_FOUND_ERR, rv);
+    }
+
+    // Create file in the subdirectory with already existing subsubdirectory
+    FileSystemChildMetadata testFileMeta(firstChildDir, u"Subfile"_ns);
+    TEST_TRY_UNWRAP(EntryId testFile,
+                    dm->GetOrCreateFile(testFileMeta, /* create */ true));
+
+    // Get handles to the original locations of the entries
+    FileSystemEntryMetadata subSubDir;
+    FileSystemEntryMetadata subSubFile;
+
+    {
+      TEST_TRY_UNWRAP(FileSystemDirectoryListing contents,
+                      dm->GetDirectoryEntries(firstChildDir, /* page */ 0u));
+      ASSERT_EQ(1u, contents.files().Length());
+      ASSERT_EQ(1u, contents.directories().Length());
+
+      subSubDir = contents.directories()[0];
+      ASSERT_STREQ(firstChildDescendantMeta.childName(), subSubDir.entryName());
+
+      subSubFile = contents.files()[0];
+      ASSERT_STREQ(testFileMeta.childName(), subSubFile.entryName());
+      ASSERT_EQ(testFile, subSubFile.entryId());
+    }
+
+    {
+      TEST_TRY_UNWRAP(Path entryPath,
+                      dm->Resolve({rootId, subSubFile.entryId()}));
+      ASSERT_EQ(2u, entryPath.Length());
+      ASSERT_STREQ(firstChildMeta.childName(), entryPath[0]);
+      ASSERT_STREQ(testFileMeta.childName(), entryPath[1]);
+    }
+
+    {
+      // Try to move file to its current location
+      FileSystemEntryMetadata src{testFile, testFileMeta.childName(),
+                                  /* is directory */ false};
+      FileSystemChildMetadata dest{firstChildDir, src.entryName()};
+      TEST_TRY_UNWRAP(EntryId moved, dm->MoveEntry(src, dest));
+      ASSERT_FALSE(moved.IsEmpty());
+      testFile = moved;
+    }
+
+    {
+      // Try to move subsubdirectory under a file
+      FileSystemEntryMetadata src{firstChildDescendant,
+                                  firstChildDescendantMeta.childName(),
+                                  /* is directory */ true};
+      FileSystemChildMetadata dest{testFile,
+                                   firstChildDescendantMeta.childName()};
+      TEST_TRY_UNWRAP_ERR(nsresult rv, dm->MoveEntry(src, dest));
+      ASSERT_NSEQ(NS_ERROR_STORAGE_CONSTRAINT, rv);
+    }
+
+    {
+      // Silently overwrite a directory with a file using rename
+      FileSystemEntryMetadata src{testFile, testFileMeta.childName(),
+                                  /* is directory */ false};
+      const FileSystemChildMetadata& dest = firstChildDescendantMeta;
+      TEST_TRY_UNWRAP(EntryId moved, dm->MoveEntry(src, dest));
+      ASSERT_FALSE(moved.IsEmpty());
+      testFile = moved;
+    }
+
+    {
+      // Move file back and recreate the directory
+      FileSystemEntryMetadata src{testFile,
+                                  firstChildDescendantMeta.childName(),
+                                  /* is directory */ false};
+
+      TEST_TRY_UNWRAP(EntryId moved, dm->MoveEntry(src, testFileMeta));
+      ASSERT_FALSE(moved.IsEmpty());
+      testFile = moved;
+
+      TEST_TRY_UNWRAP(EntryId firstChildDescendantCheck,
+                      dm->GetOrCreateDirectory(firstChildDescendantMeta,
+                                               /* create */ true));
+      ASSERT_EQ(firstChildDescendant, firstChildDescendantCheck);
+    }
+
+    {
+      // Try to rename directory to quietly overwrite a file
+      FileSystemEntryMetadata src{firstChildDescendant,
+                                  firstChildDescendantMeta.childName(),
+                                  /* is directory */ true};
+      const FileSystemChildMetadata& dest = testFileMeta;
+      TEST_TRY_UNWRAP(EntryId moved, dm->MoveEntry(src, dest));
+      ASSERT_FALSE(moved.IsEmpty());
+      firstChildDescendant = moved;
+    }
+
+    {
+      // Move directory back and recreate the file
+      FileSystemEntryMetadata src{firstChildDescendant,
+                                  testFileMeta.childName(),
+                                  /* is directory */ true};
+
+      FileSystemChildMetadata dest{firstChildDir,
+                                   firstChildDescendantMeta.childName()};
+
+      TEST_TRY_UNWRAP(EntryId moved, dm->MoveEntry(src, dest));
+      ASSERT_FALSE(moved.IsEmpty());
+      firstChildDescendant = moved;
+
+      TEST_TRY_UNWRAP(EntryId testFileCheck,
+                      dm->GetOrCreateFile(testFileMeta, /* create */ true));
+      ASSERT_EQ(testFile, testFileCheck);
+    }
+
+    {
+      // Move file one level up
+      FileSystemEntryMetadata src{testFile, testFileMeta.childName(),
+                                  /* is directory */ false};
+      FileSystemChildMetadata dest{rootId, src.entryName()};
+      TEST_TRY_UNWRAP(EntryId moved, dm->MoveEntry(src, dest));
+      ASSERT_FALSE(moved.IsEmpty());
+      testFile = moved;
+    }
+
+    {
+      // Check that listings are as expected
+      TEST_TRY_UNWRAP(FileSystemDirectoryListing contents,
+                      dm->GetDirectoryEntries(firstChildDir, 0u));
+      ASSERT_TRUE(contents.files().IsEmpty());
+      ASSERT_EQ(1u, contents.directories().Length());
+      ASSERT_STREQ(firstChildDescendantMeta.childName(),
+                   contents.directories()[0].entryName());
+    }
+
+    {
+      TEST_TRY_UNWRAP(FileSystemDirectoryListing contents,
+                      dm->GetDirectoryEntries(rootId, 0u));
+      ASSERT_EQ(1u, contents.files().Length());
+      ASSERT_EQ(1u, contents.directories().Length());
+      ASSERT_STREQ(testFileMeta.childName(), contents.files()[0].entryName());
+      ASSERT_STREQ(firstChildMeta.childName(),
+                   contents.directories()[0].entryName());
+    }
+
+    {
+      ASSERT_NO_FATAL_FAILURE(
+          AssertEntryIdMoved(subSubFile.entryId(), testFile));
+      TEST_TRY_UNWRAP(Path entryPath,
+                      dm->Resolve({rootId, subSubFile.entryId()}));
+      if (1 == sVersion) {
+        ASSERT_EQ(1u, entryPath.Length());
+        ASSERT_STREQ(testFileMeta.childName(), entryPath[0]);
+      } else {
+        ASSERT_EQ(2, sVersion);
+        // Per spec, path result is empty when no path exists.
+        ASSERT_TRUE(entryPath.IsEmpty());
+      }
+    }
+
+    {
+      // Try to get a handle to the old item
+      TEST_TRY_UNWRAP_ERR(
+          nsresult rv, dm->GetOrCreateFile(testFileMeta, /* create */ false));
+      ASSERT_NSEQ(NS_ERROR_DOM_NOT_FOUND_ERR, rv);
+    }
+
+    {
+      // Try to move + rename file one level down to collide with a
+      // subSubDirectory, silently overwriting it
+      FileSystemEntryMetadata src{testFile, testFileMeta.childName(),
+                                  /* is directory */ false};
+      FileSystemChildMetadata dest{firstChildDir,
+                                   firstChildDescendantMeta.childName()};
+      TEST_TRY_UNWRAP(EntryId moved, dm->MoveEntry(src, dest));
+      ASSERT_FALSE(moved.IsEmpty());
+      testFile = moved;
+    }
+
+    {
+      // Restore filename, move file to its original location and recreate
+      // the overwritten directory
+      FileSystemEntryMetadata src{testFile,
+                                  firstChildDescendantMeta.childName(),
+                                  /* is directory */ false};
+      FileSystemChildMetadata dest{rootId, testFileMeta.childName()};
+      TEST_TRY_UNWRAP(EntryId moved, dm->MoveEntry(src, dest));
+      ASSERT_FALSE(moved.IsEmpty());
+      testFile = moved;
+
+      FileSystemChildMetadata oldLocation{firstChildDir,
+                                          firstChildDescendantMeta.childName()};
+
+      // Is there still something out there?
+      TEST_TRY_UNWRAP_ERR(nsresult rv,
+                          dm->GetOrCreateFile(oldLocation, /* create */ false));
+      ASSERT_NSEQ(NS_ERROR_DOM_NOT_FOUND_ERR, rv);
+
+      TEST_TRY_UNWRAP(EntryId firstChildDescendantCheck,
+                      dm->GetOrCreateDirectory(oldLocation, /* create */ true));
+      ASSERT_EQ(firstChildDescendant, firstChildDescendantCheck);
+    }
+
+    // Rename file first and then try to move it to collide with
+    // subSubDirectory, silently overwriting it
+    {
+      // Rename
+      FileSystemEntryMetadata src{testFile, testFileMeta.childName(),
+                                  /* is directory */ false};
+      FileSystemChildMetadata dest{rootId,
+                                   firstChildDescendantMeta.childName()};
+      TEST_TRY_UNWRAP(EntryId moved, dm->MoveEntry(src, dest));
+      ASSERT_FALSE(moved.IsEmpty());
+      testFile = moved;
+    }
+
+    {
+      // Try to move one level down
+      FileSystemEntryMetadata src{testFile,
+                                  firstChildDescendantMeta.childName(),
+                                  /* is directory */ false};
+      FileSystemChildMetadata dest{firstChildDir,
+                                   firstChildDescendantMeta.childName()};
+      TEST_TRY_UNWRAP(EntryId moved, dm->MoveEntry(src, dest));
+      ASSERT_FALSE(moved.IsEmpty());
+      testFile = moved;
+    }
+
+    {
+      // Move the file back and recreate the directory
+      FileSystemEntryMetadata src{testFile,
+                                  firstChildDescendantMeta.childName(),
+                                  /* is directory */ false};
+      FileSystemChildMetadata dest{rootId,
+                                   firstChildDescendantMeta.childName()};
+      TEST_TRY_UNWRAP(EntryId moved, dm->MoveEntry(src, dest));
+      ASSERT_FALSE(moved.IsEmpty());
+      testFile = moved;
+
+      FileSystemChildMetadata oldLocation{firstChildDir,
+                                          firstChildDescendantMeta.childName()};
+
+      // Is there still something out there?
+      TEST_TRY_UNWRAP_ERR(nsresult rv,
+                          dm->GetOrCreateFile(oldLocation, /* create */ false));
+      ASSERT_NSEQ(NS_ERROR_DOM_NOT_FOUND_ERR, rv);
+
+      TEST_TRY_UNWRAP(EntryId firstChildDescendantCheck,
+                      dm->GetOrCreateDirectory(oldLocation, /* create */ true));
+      ASSERT_EQ(firstChildDescendant, firstChildDescendantCheck);
+    }
+
+    {
+      // Try to move subSubDirectory one level up to quietly overwrite a file
+      FileSystemEntryMetadata src{firstChildDescendant,
+                                  firstChildDescendantMeta.childName(),
+                                  /* is directory */ true};
+      FileSystemChildMetadata dest{rootId,
+                                   firstChildDescendantMeta.childName()};
+      TEST_TRY_UNWRAP(EntryId moved, dm->MoveEntry(src, dest));
+      ASSERT_FALSE(moved.IsEmpty());
+      firstChildDescendant = moved;
+    }
+
+    {
+      // Move subSubDirectory back one level down and recreate the file
+      FileSystemEntryMetadata src{firstChildDescendant,
+                                  firstChildDescendantMeta.childName(),
+                                  /* is directory */ true};
+      FileSystemChildMetadata dest{firstChildDir,
+                                   firstChildDescendantMeta.childName()};
+      TEST_TRY_UNWRAP(EntryId moved, dm->MoveEntry(src, dest));
+      ASSERT_FALSE(moved.IsEmpty());
+      firstChildDescendant = moved;
+
+      FileSystemChildMetadata oldLocation{rootId,
+                                          firstChildDescendantMeta.childName()};
+
+      // We should no longer find anything there
+      TEST_TRY_UNWRAP_ERR(nsresult rv, dm->GetOrCreateDirectory(
+                                           oldLocation, /* create */ false));
+      ASSERT_NSEQ(NS_ERROR_DOM_NOT_FOUND_ERR, rv);
+
+      TEST_TRY_UNWRAP(EntryId testFileCheck,
+                      dm->GetOrCreateFile(oldLocation, /* create */ true));
+      ASSERT_NO_FATAL_FAILURE(AssertEntryIdCollision(testFile, testFileCheck));
+      testFile = testFileCheck;
+    }
+
+    // Create a new file in the subsubdirectory
+    FileSystemChildMetadata newFileMeta{firstChildDescendant,
+                                        testFileMeta.childName()};
+    EntryId oldFirstChildDescendant = firstChildDescendant;
+
+    TEST_TRY_UNWRAP(EntryId newFile,
+                    dm->GetOrCreateFile(newFileMeta, /* create */ true));
+
+    {
+      TEST_TRY_UNWRAP(Path entryPath, dm->Resolve({rootId, newFile}));
+      ASSERT_EQ(3u, entryPath.Length());
+      ASSERT_STREQ(firstChildMeta.childName(), entryPath[0]);
+      ASSERT_STREQ(firstChildDescendantMeta.childName(), entryPath[1]);
+      ASSERT_STREQ(testFileMeta.childName(), entryPath[2]);
+    }
+
+    {
+      // Move subSubDirectory one level up and rename it to testFile's old name
+      FileSystemEntryMetadata src{firstChildDescendant,
+                                  firstChildDescendantMeta.childName(),
+                                  /* is directory */ true};
+      FileSystemChildMetadata dest{rootId, testFileMeta.childName()};
+      TEST_TRY_UNWRAP(EntryId moved, dm->MoveEntry(src, dest));
+      ASSERT_FALSE(moved.IsEmpty());
+      firstChildDescendant = moved;
+    }
+
+    {
+      // Try to get handles to the moved items
+      TEST_TRY_UNWRAP_ERR(nsresult rv,
+                          dm->GetOrCreateDirectory(firstChildDescendantMeta,
+                                                   /* create */ false));
+      ASSERT_NSEQ(NS_ERROR_DOM_NOT_FOUND_ERR, rv);
+
+      //  Still under the same parent which was moved
+      if (1 == sVersion) {
+        TEST_TRY_UNWRAP(EntryId handle,
+                        dm->GetOrCreateFile(newFileMeta, /* create */ false));
+        ASSERT_EQ(handle, newFile);
+
+        TEST_TRY_UNWRAP(
+            handle, dm->GetOrCreateDirectory({rootId, testFileMeta.childName()},
+                                             /* create */ false));
+        ASSERT_EQ(handle, firstChildDescendant);
+      } else if (2 == sVersion) {
+        TEST_TRY_UNWRAP_ERR(
+            rv, dm->GetOrCreateFile(newFileMeta, /* create */ false));
+        ASSERT_NSEQ(NS_ERROR_DOM_NOT_FOUND_ERR, rv);
+
+        TEST_TRY_UNWRAP(
+            EntryId newFileCheck,
+            dm->GetOrCreateFile({firstChildDescendant, newFileMeta.childName()},
+                                /* create */ false));
+        ASSERT_FALSE(newFileCheck.IsEmpty());
+      } else {
+        ASSERT_FALSE(false)
+        << "Unknown database version";
+      }
+    }
+
+    {
+      // Check that new file path is as expected
+      TEST_TRY_UNWRAP(
+          EntryId newFileCheck,
+          dm->GetOrCreateFile({firstChildDescendant, newFileMeta.childName()},
+                              /* create */ false));
+      ASSERT_NO_FATAL_FAILURE(AssertEntryIdMoved(newFileCheck, newFile));
+      newFile = newFileCheck;
+
+      TEST_TRY_UNWRAP(Path entryPath, dm->Resolve({rootId, newFile}));
+      ASSERT_EQ(2u, entryPath.Length());
+      ASSERT_STREQ(testFileMeta.childName(), entryPath[0]);
+      ASSERT_STREQ(testFileMeta.childName(), entryPath[1]);
+    }
+
+    // Move first file and subSubDirectory back one level down keeping the names
+    {
+      FileSystemEntryMetadata src{testFile,
+                                  firstChildDescendantMeta.childName(),
+                                  /* is directory */ false};
+      FileSystemChildMetadata dest{firstChildDir,
+                                   firstChildDescendantMeta.childName()};
+
+      // Flag is ignored
+      TEST_TRY_UNWRAP(EntryId moved, dm->MoveEntry(src, dest));
+      ASSERT_FALSE(moved.IsEmpty());
+      testFile = moved;
+    }
+
+    {
+      // Then move the directory
+      FileSystemEntryMetadata src{firstChildDescendant,
+                                  testFileMeta.childName(),
+                                  /* is directory */ true};
+      FileSystemChildMetadata dest{firstChildDir, testFileMeta.childName()};
+
+      // Flag is ignored
+      TEST_TRY_UNWRAP(EntryId moved, dm->MoveEntry(src, dest));
+      ASSERT_FALSE(moved.IsEmpty());
+      firstChildDescendant = moved;
+    }
+
+    // Check that listings are as expected
+    {
+      TEST_TRY_UNWRAP(FileSystemDirectoryListing contents,
+                      dm->GetDirectoryEntries(rootId, 0u));
+      ASSERT_TRUE(contents.files().IsEmpty());
+      ASSERT_EQ(1u, contents.directories().Length());
+      ASSERT_STREQ(firstChildMeta.childName(),
+                   contents.directories()[0].entryName());
+    }
+
+    {
+      TEST_TRY_UNWRAP(FileSystemDirectoryListing contents,
+                      dm->GetDirectoryEntries(firstChildDir, 0u));
+      ASSERT_EQ(1u, contents.files().Length());
+      ASSERT_EQ(1u, contents.directories().Length());
+      ASSERT_STREQ(firstChildDescendantMeta.childName(),
+                   contents.files()[0].entryName());
+      ASSERT_STREQ(testFileMeta.childName(),
+                   contents.directories()[0].entryName());
+    }
+
+    {
+      TEST_TRY_UNWRAP(FileSystemDirectoryListing contents,
+                      dm->GetDirectoryEntries(firstChildDescendant, 0u));
+      ASSERT_EQ(1u, contents.files().Length());
+      ASSERT_TRUE(contents.directories().IsEmpty());
+      ASSERT_STREQ(testFileMeta.childName(), contents.files()[0].entryName());
+    }
+
+    // Names are swapped
+    {
+      TEST_TRY_UNWRAP(Path entryPath, dm->Resolve({rootId, testFile}));
+      ASSERT_EQ(2u, entryPath.Length());
+      ASSERT_STREQ(firstChildMeta.childName(), entryPath[0]);
+      ASSERT_STREQ(firstChildDescendantMeta.childName(), entryPath[1]);
+    }
+
+    {
+      TEST_TRY_UNWRAP(Path entryPath,
+                      dm->Resolve({rootId, firstChildDescendant}));
+      ASSERT_EQ(2u, entryPath.Length());
+      ASSERT_STREQ(firstChildMeta.childName(), entryPath[0]);
+      ASSERT_STREQ(testFileMeta.childName(), entryPath[1]);
+    }
+
+    {
+      // Check that new file path is also as expected
+      TEST_TRY_UNWRAP(
+          EntryId newFileCheck,
+          dm->GetOrCreateFile({firstChildDescendant, newFileMeta.childName()},
+                              /* create */ false));
+      ASSERT_NO_FATAL_FAILURE(AssertEntryIdMoved(newFileCheck, newFile));
+      newFile = newFileCheck;
+
+      TEST_TRY_UNWRAP(Path entryPath, dm->Resolve({rootId, newFile}));
+      ASSERT_EQ(3u, entryPath.Length());
+      ASSERT_STREQ(firstChildMeta.childName(), entryPath[0]);
+      ASSERT_STREQ(testFileMeta.childName(), entryPath[1]);
+      ASSERT_STREQ(testFileMeta.childName(), entryPath[2]);
+    }
+
+    {
+      // Try to get handles to the old items
+      TEST_TRY_UNWRAP_ERR(
+          nsresult rv, dm->GetOrCreateFile({rootId, testFileMeta.childName()},
+                                           /* create */ false));
+      ASSERT_NSEQ(NS_ERROR_DOM_NOT_FOUND_ERR, rv);
+
+      TEST_TRY_UNWRAP_ERR(
+          rv,
+          dm->GetOrCreateFile({rootId, firstChildDescendantMeta.childName()},
+                              /* create */ false));
+      ASSERT_NSEQ(NS_ERROR_DOM_NOT_FOUND_ERR, rv);
+
+      TEST_TRY_UNWRAP_ERR(
+          rv, dm->GetOrCreateDirectory({rootId, testFileMeta.childName()},
+                                       /* create */ false));
+      ASSERT_NSEQ(NS_ERROR_DOM_NOT_FOUND_ERR, rv);
+
+      TEST_TRY_UNWRAP_ERR(rv,
+                          dm->GetOrCreateDirectory(
+                              {rootId, firstChildDescendantMeta.childName()},
+                              /* create */ false));
+      ASSERT_NSEQ(NS_ERROR_DOM_NOT_FOUND_ERR, rv);
+
+      TEST_TRY_UNWRAP_ERR(
+          rv, dm->GetOrCreateFile({firstChildDir, testFileMeta.childName()},
+                                  /* create */ false));
+      ASSERT_NSEQ(NS_ERROR_DOM_TYPE_MISMATCH_ERR, rv);
+
+      TEST_TRY_UNWRAP_ERR(
+          rv, dm->GetOrCreateDirectory(
+                  {firstChildDir, firstChildDescendantMeta.childName()},
+                  /* create */ false));
+      ASSERT_NSEQ(NS_ERROR_DOM_TYPE_MISMATCH_ERR, rv);
+
+      TEST_TRY_UNWRAP_ERR(
+          rv, dm->GetOrCreateFile({testFile, newFileMeta.childName()},
+                                  /* create */ false));
+      ASSERT_NSEQ(NS_ERROR_DOM_NOT_FOUND_ERR, rv);
+    }
+  };
+
+  PerformOnIOThread(std::move(ioTask));
+}
+
+INSTANTIATE_TEST_SUITE_P(TestDatabaseManagerVersions,
+                         TestFileSystemDatabaseManagerVersions,
+                         testing::Values(1, 2));
+
+}  // namespace mozilla::dom::fs::test
diff --git a/dom/fs/test/gtest/parent/datamodel/moz.build b/dom/fs/test/gtest/parent/datamodel/moz.build
new file mode 100644
index 0000000000..6369aec649
--- /dev/null
+++ b/dom/fs/test/gtest/parent/datamodel/moz.build
@@ -0,0 +1,22 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, you can obtain one at http://mozilla.org/MPL/2.0/.
+
+UNIFIED_SOURCES = [
+    "TestFileSystemDataManager.cpp",
+    "TestFileSystemDataManagerVersions.cpp",
+]
+
+include("/ipc/chromium/chromium-config.mozbuild")
+
+FINAL_LIBRARY = "xul-gtest"
+
+LOCAL_INCLUDES += [
+    "/dom/fs/include",
+    "/dom/fs/parent",
+    "/dom/fs/parent/datamodel",
+    "/dom/fs/test/gtest",
+    "/dom/fs/test/gtest/parent",
+]
diff --git a/dom/fs/test/gtest/parent/moz.build b/dom/fs/test/gtest/parent/moz.build
new file mode 100644
index 0000000000..9197c6ade2
--- /dev/null
+++ b/dom/fs/test/gtest/parent/moz.build
@@ -0,0 +1,21 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, you can obtain one at http://mozilla.org/MPL/2.0/.
+
+TEST_DIRS += ["datamodel"]
+
+UNIFIED_SOURCES = [
+    "TestFileSystemHashSource.cpp",
+    "TestFileSystemQuotaClient.cpp",
+]
+
+include("/ipc/chromium/chromium-config.mozbuild")
+
+FINAL_LIBRARY = "xul-gtest"
+
+LOCAL_INCLUDES += [
+    "/dom/fs/parent",
+    "/dom/fs/test/gtest",
+]
diff --git a/dom/fs/test/gtest/shared/TestFileSystemHelpers.cpp b/dom/fs/test/gtest/shared/TestFileSystemHelpers.cpp
new file mode 100644
index 0000000000..ed38026634
--- /dev/null
+++ b/dom/fs/test/gtest/shared/TestFileSystemHelpers.cpp
@@ -0,0 +1,179 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "gtest/gtest.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/Unused.h"
+#include "mozilla/dom/FileSystemHelpers.h"
+
+namespace mozilla::dom::fs {
+
+namespace {
+
+class TestObject {
+ public:
+  explicit TestObject(uint32_t aExpectedAddRefCnt = 0,
+                      uint32_t aExpectedAddRegCnt = 0)
+      : mExpectedAddRefCnt(aExpectedAddRefCnt),
+        mExpectedAddRegCnt(aExpectedAddRegCnt),
+        mAddRefCnt(0),
+        mAddRegCnt(0),
+        mRefCnt(0),
+        mRegCnt(0),
+        mClosed(false) {}
+
+  uint32_t AddRef() {
+    mRefCnt++;
+    mAddRefCnt++;
+    return mRefCnt;
+  }
+
+  uint32_t Release() {
+    EXPECT_TRUE(mRefCnt > 0);
+    mRefCnt--;
+    if (mRefCnt == 0) {
+      delete this;
+      return 0;
+    }
+    return mRefCnt;
+  }
+
+  void Register() {
+    EXPECT_FALSE(mClosed);
+    mRegCnt++;
+    mAddRegCnt++;
+  }
+
+  void Unregister() {
+    EXPECT_FALSE(mClosed);
+    EXPECT_TRUE(mRegCnt > 0);
+    mRegCnt--;
+    if (mRegCnt == 0) {
+      mClosed = true;
+    }
+  }
+
+  void Foo() const {}
+
+ private:
+  ~TestObject() {
+    if (mExpectedAddRefCnt > 0) {
+      EXPECT_EQ(mAddRefCnt, mExpectedAddRefCnt);
+    }
+    if (mExpectedAddRegCnt > 0) {
+      EXPECT_EQ(mAddRegCnt, mExpectedAddRegCnt);
+    }
+  }
+
+  uint32_t mExpectedAddRefCnt;
+  uint32_t mExpectedAddRegCnt;
+  uint32_t mAddRefCnt;
+  uint32_t mAddRegCnt;
+  uint32_t mRefCnt;
+  uint32_t mRegCnt;
+  bool mClosed;
+};
+
+}  // namespace
+
+TEST(TestFileSystemHelpers_Registered, Construct_Default)
+{
+  { Registered<TestObject> testObject; }
+}
+
+TEST(TestFileSystemHelpers_Registered, Construct_Copy)
+{
+  {
+    Registered<TestObject> testObject1(MakeRefPtr<TestObject>(2, 2));
+    Registered<TestObject> testObject2(testObject1);
+    testObject2 = nullptr;
+  }
+}
+
+TEST(TestFileSystemHelpers_Registered, Construct_Move)
+{
+  {
+    Registered<TestObject> testObject1(MakeRefPtr<TestObject>(1, 1));
+    Registered<TestObject> testObject2(std::move(testObject1));
+  }
+}
+
+TEST(TestFileSystemHelpers_Registered, Construct_FromRefPtr)
+{
+  { Registered<TestObject> testObject(MakeRefPtr<TestObject>(1, 1)); }
+}
+
+TEST(TestFileSystemHelpers_Registered, Operator_Assign_FromNullPtr)
+{
+  {
+    Registered<TestObject> testObject;
+    testObject = nullptr;
+  }
+}
+
+TEST(TestFileSystemHelpers_Registered, Operator_Assign_Copy)
+{
+  {
+    Registered<TestObject> testObject1(MakeRefPtr<TestObject>(2, 2));
+    Registered<TestObject> testObject2;
+    testObject2 = testObject1;
+  }
+}
+
+TEST(TestFileSystemHelpers_Registered, Operator_Assign_Move)
+{
+  {
+    Registered<TestObject> testObject1(MakeRefPtr<TestObject>(1, 1));
+    Registered<TestObject> testObject2;
+    testObject2 = std::move(testObject1);
+  }
+}
+
+TEST(TestFileSystemHelpers_Registered, Method_Inspect)
+{
+  {
+    Registered<TestObject> testObject1(MakeRefPtr<TestObject>(1, 1));
+    const RefPtr<TestObject>& testObject2 = testObject1.inspect();
+    Unused << testObject2;
+  }
+}
+
+TEST(TestFileSystemHelpers_Registered, Method_Unwrap)
+{
+  {
+    Registered<TestObject> testObject1(MakeRefPtr<TestObject>(1, 1));
+    RefPtr<TestObject> testObject2 = testObject1.unwrap();
+    Unused << testObject2;
+  }
+}
+
+TEST(TestFileSystemHelpers_Registered, Method_Get)
+{
+  {
+    Registered<TestObject> testObject1(MakeRefPtr<TestObject>(1, 1));
+    TestObject* testObject2 = testObject1.get();
+    Unused << testObject2;
+  }
+}
+
+TEST(TestFileSystemHelpers_Registered, Operator_Conversion_ToRawPtr)
+{
+  {
+    Registered<TestObject> testObject1(MakeRefPtr<TestObject>(1, 1));
+    TestObject* testObject2 = testObject1;
+    Unused << testObject2;
+  }
+}
+
+TEST(TestFileSystemHelpers_Registered, Operator_Dereference_ToRawPtr)
+{
+  {
+    Registered<TestObject> testObject(MakeRefPtr<TestObject>(1, 1));
+    testObject->Foo();
+  }
+}
+
+}  // namespace mozilla::dom::fs
diff --git a/dom/fs/test/gtest/shared/moz.build b/dom/fs/test/gtest/shared/moz.build
new file mode 100644
index 0000000000..e8feae8c57
--- /dev/null
+++ b/dom/fs/test/gtest/shared/moz.build
@@ -0,0 +1,16 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, you can obtain one at http://mozilla.org/MPL/2.0/.
+
+UNIFIED_SOURCES = [
+    "TestFileSystemHelpers.cpp",
+]
+
+FINAL_LIBRARY = "xul-gtest"
+
+LOCAL_INCLUDES += [
+    "/dom/fs/shared",
+    "/dom/fs/test/gtest",
+]
diff --git a/dom/fs/test/mochitest/head.js b/dom/fs/test/mochitest/head.js
new file mode 100644
index 0000000000..167e7c0c52
--- /dev/null
+++ b/dom/fs/test/mochitest/head.js
@@ -0,0 +1,82 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+async function require_module(id) {
+  if (!require_module.moduleLoader) {
+    const { ModuleLoader } = await import(
+      "/tests/dom/quota/test/modules/ModuleLoader.mjs"
+    );
+
+    const base = window.location.href;
+
+    const depth = "../../../../";
+
+    const { Assert } = await import("/tests/dom/quota/test/modules/Assert.mjs");
+
+    const { Utils } = await import("/tests/dom/quota/test/modules/Utils.mjs");
+
+    const proto = {
+      Assert,
+      Cr: SpecialPowers.Cr,
+      navigator,
+      TextEncoder,
+      Utils,
+    };
+
+    require_module.moduleLoader = new ModuleLoader(base, depth, proto);
+  }
+
+  return require_module.moduleLoader.require(id);
+}
+
+async function run_test_in_worker(script) {
+  const { runTestInWorker } = await import(
+    "/tests/dom/quota/test/modules/WorkerDriver.mjs"
+  );
+
+  const base = window.location.href;
+
+  const listener = {
+    onOk(value, message) {
+      ok(value, message);
+    },
+    onIs(a, b, message) {
+      is(a, b, message);
+    },
+    onInfo(message) {
+      info(message);
+    },
+  };
+
+  await runTestInWorker(script, base, listener);
+}
+
+// XXX This can be removed once we use <profile>/storage. See bug 1798015.
+async function removeAllEntries() {
+  const root = await navigator.storage.getDirectory();
+  for await (const value of root.values()) {
+    root.removeEntry(value.name, { recursive: true });
+  }
+}
+
+add_setup(async function () {
+  const { setStoragePrefs, clearStoragesForOrigin } = await import(
+    "/tests/dom/quota/test/modules/StorageUtils.mjs"
+  );
+
+  const optionalPrefsToSet = [
+    ["dom.fs.enabled", true],
+    ["dom.fs.writable_file_stream.enabled", true],
+    ["dom.workers.modules.enabled", true],
+  ];
+
+  await setStoragePrefs(optionalPrefsToSet);
+
+  SimpleTest.registerCleanupFunction(async function () {
+    await removeAllEntries();
+
+    await clearStoragesForOrigin(SpecialPowers.wrap(document).nodePrincipal);
+  });
+});
diff --git a/dom/fs/test/mochitest/mochitest.toml b/dom/fs/test/mochitest/mochitest.toml
new file mode 100644
index 0000000000..e138469768
--- /dev/null
+++ b/dom/fs/test/mochitest/mochitest.toml
@@ -0,0 +1,35 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+[DEFAULT]
+skip-if = ["xorigin"]
+support-files = ["head.js"]
+
+# Skip all tests if xorigin since we'll fail GetStorage() with ePartitionForeignOrDeny
+
+["test_basics.html"]
+scheme = "https"
+skip-if = [
+  "os == 'win'", # Bug 1841281
+  "os == 'linux' && debug",  # Bug 1841281
+  "os == 'mac' && debug", # Bug 1841281
+]
+
+["test_basics_worker.html"]
+scheme = "https"
+
+["test_fileSystemDirectoryHandle.html"]
+scheme = "https"
+
+["test_fileSystemDirectoryHandle_worker.html"]
+scheme = "https"
+
+["test_syncAccessHandle_worker.html"]
+scheme = "https"
+
+["test_writableFileStream.html"]
+scheme = "https"
+
+["test_writableFileStream_worker.html"]
+scheme = "https"
diff --git a/dom/fs/test/mochitest/test_basics.html b/dom/fs/test/mochitest/test_basics.html
new file mode 100644
index 0000000000..5c609233b5
--- /dev/null
+++ b/dom/fs/test/mochitest/test_basics.html
@@ -0,0 +1,28 @@
+<!--
+  Any copyright is dedicated to the Public Domain.
+  http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>File System Test</title>
+
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+
+  <script type="text/javascript" src="head.js"></script>
+  <script type="text/javascript">
+    add_task(async function init() {
+      const testSet = "dom/fs/test/common/test_basics.js";
+
+      const testCases = await require_module(testSet);
+
+      Object.values(testCases).forEach(testItem => {
+        add_task(testItem);
+      });
+    });
+  </script>
+</head>
+
+<body></body>
+
+</html>
diff --git a/dom/fs/test/mochitest/test_basics_worker.html b/dom/fs/test/mochitest/test_basics_worker.html
new file mode 100644
index 0000000000..72ad7b8c41
--- /dev/null
+++ b/dom/fs/test/mochitest/test_basics_worker.html
@@ -0,0 +1,22 @@
+<!--
+  Any copyright is dedicated to the Public Domain.
+  http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>File System Test</title>
+
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+
+  <script type="text/javascript" src="head.js"></script>
+  <script type="text/javascript">
+    add_task(async function worker() {
+      await run_test_in_worker("worker/test_basics_worker.js");
+    });
+  </script>
+</head>
+
+<body></body>
+
+</html>
diff --git a/dom/fs/test/mochitest/test_fileSystemDirectoryHandle.html b/dom/fs/test/mochitest/test_fileSystemDirectoryHandle.html
new file mode 100644
index 0000000000..35f3a72e2f
--- /dev/null
+++ b/dom/fs/test/mochitest/test_fileSystemDirectoryHandle.html
@@ -0,0 +1,28 @@
+<!--
+  Any copyright is dedicated to the Public Domain.
+  http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>File System Test</title>
+
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+
+  <script type="text/javascript" src="head.js"></script>
+  <script type="text/javascript">
+    add_task(async function init() {
+      const testSet = "dom/fs/test/common/test_fileSystemDirectoryHandle.js";
+
+      const testCases = await require_module(testSet);
+
+      Object.values(testCases).forEach(testItem => {
+        add_task(testItem);
+      });
+    });
+  </script>
+</head>
+
+<body></body>
+
+</html>
diff --git a/dom/fs/test/mochitest/test_fileSystemDirectoryHandle_worker.html b/dom/fs/test/mochitest/test_fileSystemDirectoryHandle_worker.html
new file mode 100644
index 0000000000..2f52079435
--- /dev/null
+++ b/dom/fs/test/mochitest/test_fileSystemDirectoryHandle_worker.html
@@ -0,0 +1,22 @@
+<!--
+  Any copyright is dedicated to the Public Domain.
+  http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>File System Test</title>
+
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+
+  <script type="text/javascript" src="head.js"></script>
+  <script type="text/javascript">
+    add_task(async function worker() {
+      await run_test_in_worker("worker/test_fileSystemDirectoryHandle_worker.js");
+    });
+  </script>
+</head>
+
+<body></body>
+
+</html>
diff --git a/dom/fs/test/mochitest/test_syncAccessHandle_worker.html b/dom/fs/test/mochitest/test_syncAccessHandle_worker.html
new file mode 100644
index 0000000000..42980b1d55
--- /dev/null
+++ b/dom/fs/test/mochitest/test_syncAccessHandle_worker.html
@@ -0,0 +1,22 @@
+<!--
+  Any copyright is dedicated to the Public Domain.
+  http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>File System Test</title>
+
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+
+  <script type="text/javascript" src="head.js"></script>
+  <script type="text/javascript">
+    add_task(async function worker() {
+      await run_test_in_worker("worker/test_syncAccessHandle_worker.js");
+    });
+  </script>
+</head>
+
+<body></body>
+
+</html>
diff --git a/dom/fs/test/mochitest/test_writableFileStream.html b/dom/fs/test/mochitest/test_writableFileStream.html
new file mode 100644
index 0000000000..3d39349ef5
--- /dev/null
+++ b/dom/fs/test/mochitest/test_writableFileStream.html
@@ -0,0 +1,31 @@
+<!--
+  Any copyright is dedicated to the Public Domain.
+  http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>File System Test</title>
+
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+
+  <script type="text/javascript" src="head.js"></script>
+  <script type="text/javascript">
+    add_task(async function init() {
+      const testSet = "dom/fs/test/common/test_writableFileStream.js";
+
+      const testCases = await require_module(testSet);
+
+      Object.values(testCases).forEach(testItem => {
+        // We can't shrink storage size in a mochitest.
+        if (testItem.name != "quotaTest") {
+          add_task(testItem);
+        }
+      });
+    });
+  </script>
+</head>
+
+<body></body>
+
+</html>
diff --git a/dom/fs/test/mochitest/test_writableFileStream_worker.html b/dom/fs/test/mochitest/test_writableFileStream_worker.html
new file mode 100644
index 0000000000..a762e78c3f
--- /dev/null
+++ b/dom/fs/test/mochitest/test_writableFileStream_worker.html
@@ -0,0 +1,22 @@
+<!--
+  Any copyright is dedicated to the Public Domain.
+  http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>File System Test</title>
+
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+
+  <script type="text/javascript" src="head.js"></script>
+  <script type="text/javascript">
+    add_task(async function worker() {
+      await run_test_in_worker("worker/test_writableFileStream_worker.js");
+    });
+  </script>
+</head>
+
+<body></body>
+
+</html>
diff --git a/dom/fs/test/mochitest/worker/.eslintrc.js b/dom/fs/test/mochitest/worker/.eslintrc.js
new file mode 100644
index 0000000000..93bf938654
--- /dev/null
+++ b/dom/fs/test/mochitest/worker/.eslintrc.js
@@ -0,0 +1,12 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+"use strict";
+
+module.exports = {
+  env: {
+    worker: true,
+  },
+};
diff --git a/dom/fs/test/mochitest/worker/dummy.js b/dom/fs/test/mochitest/worker/dummy.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/dom/fs/test/mochitest/worker/dummy.js
diff --git a/dom/fs/test/mochitest/worker/head.js b/dom/fs/test/mochitest/worker/head.js
new file mode 100644
index 0000000000..72e1869bde
--- /dev/null
+++ b/dom/fs/test/mochitest/worker/head.js
@@ -0,0 +1,22 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+async function require_module(id) {
+  if (!require_module.moduleLoader) {
+    importScripts("/tests/dom/quota/test/modules/worker/ModuleLoader.js");
+
+    const base = location.href;
+
+    const depth = "../../../../../";
+
+    importScripts("/tests/dom/quota/test/modules/worker/Assert.js");
+
+    importScripts("/tests/dom/quota/test/modules/worker/Utils.js");
+
+    require_module.moduleLoader = new globalThis.ModuleLoader(base, depth);
+  }
+
+  return require_module.moduleLoader.require(id);
+}
diff --git a/dom/fs/test/mochitest/worker/mochitest.toml b/dom/fs/test/mochitest/worker/mochitest.toml
new file mode 100644
index 0000000000..830c8f267d
--- /dev/null
+++ b/dom/fs/test/mochitest/worker/mochitest.toml
@@ -0,0 +1,15 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+[DEFAULT]
+support-files = [
+  "head.js",
+  "test_basics_worker.js",
+  "test_fileSystemDirectoryHandle_worker.js",
+  "test_syncAccessHandle_worker.js",
+  "test_writableFileStream_worker.js",
+]
+
+["dummy.js"]
+skip-if = ["true"]
diff --git a/dom/fs/test/mochitest/worker/test_basics_worker.js b/dom/fs/test/mochitest/worker/test_basics_worker.js
new file mode 100644
index 0000000000..e4a4958071
--- /dev/null
+++ b/dom/fs/test/mochitest/worker/test_basics_worker.js
@@ -0,0 +1,11 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+add_task(async function init() {
+  const testCases = await require_module("dom/fs/test/common/test_basics.js");
+  Object.values(testCases).forEach(async testItem => {
+    add_task(testItem);
+  });
+});
diff --git a/dom/fs/test/mochitest/worker/test_fileSystemDirectoryHandle_worker.js b/dom/fs/test/mochitest/worker/test_fileSystemDirectoryHandle_worker.js
new file mode 100644
index 0000000000..d4ba0b387c
--- /dev/null
+++ b/dom/fs/test/mochitest/worker/test_fileSystemDirectoryHandle_worker.js
@@ -0,0 +1,13 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+add_task(async function init() {
+  const testCases = await require_module(
+    "dom/fs/test/common/test_fileSystemDirectoryHandle.js"
+  );
+  Object.values(testCases).forEach(async testItem => {
+    add_task(testItem);
+  });
+});
diff --git a/dom/fs/test/mochitest/worker/test_syncAccessHandle_worker.js b/dom/fs/test/mochitest/worker/test_syncAccessHandle_worker.js
new file mode 100644
index 0000000000..be53a5a7e1
--- /dev/null
+++ b/dom/fs/test/mochitest/worker/test_syncAccessHandle_worker.js
@@ -0,0 +1,16 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+add_task(async function init() {
+  const testCases = await require_module(
+    "dom/fs/test/common/test_syncAccessHandle.js"
+  );
+  Object.values(testCases).forEach(async testItem => {
+    // We can't shrink storage size in a mochitest.
+    if (testItem.name != "quotaTest") {
+      add_task(testItem);
+    }
+  });
+});
diff --git a/dom/fs/test/mochitest/worker/test_writableFileStream_worker.js b/dom/fs/test/mochitest/worker/test_writableFileStream_worker.js
new file mode 100644
index 0000000000..f294a719db
--- /dev/null
+++ b/dom/fs/test/mochitest/worker/test_writableFileStream_worker.js
@@ -0,0 +1,16 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+add_task(async function init() {
+  const testCases = await require_module(
+    "dom/fs/test/common/test_writableFileStream.js"
+  );
+  Object.values(testCases).forEach(async testItem => {
+    // We can't shrink storage size in a mochitest.
+    if (testItem.name != "quotaTest") {
+      add_task(testItem);
+    }
+  });
+});
diff --git a/dom/fs/test/moz.build b/dom/fs/test/moz.build
new file mode 100644
index 0000000000..5f4ac34fca
--- /dev/null
+++ b/dom/fs/test/moz.build
@@ -0,0 +1,16 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+TEST_DIRS += [
+    "common",
+    "gtest",
+    "xpcshell",
+]
+
+MOCHITEST_MANIFESTS += [
+    "mochitest/mochitest.toml",
+    "mochitest/worker/mochitest.toml",
+]
diff --git a/dom/fs/test/xpcshell/head.js b/dom/fs/test/xpcshell/head.js
new file mode 100644
index 0000000000..4138e46ac9
--- /dev/null
+++ b/dom/fs/test/xpcshell/head.js
@@ -0,0 +1,100 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+async function require_module(id) {
+  if (!require_module.moduleLoader) {
+    const { ModuleLoader } = ChromeUtils.importESModule(
+      "resource://testing-common/dom/quota/test/modules/ModuleLoader.sys.mjs"
+    );
+
+    const base = Services.io.newFileURI(do_get_file("")).spec;
+
+    const depth = "../../../../";
+
+    Cu.importGlobalProperties(["storage"]);
+
+    const { Utils } = ChromeUtils.importESModule(
+      "resource://testing-common/dom/quota/test/modules/Utils.sys.mjs"
+    );
+
+    const proto = {
+      Assert,
+      Cr,
+      DOMException,
+      navigator: {
+        storage,
+      },
+      TextEncoder,
+      Utils,
+    };
+
+    require_module.moduleLoader = new ModuleLoader(base, depth, proto);
+  }
+
+  return require_module.moduleLoader.require(id);
+}
+
+async function run_test_in_worker(script) {
+  const { runTestInWorker } = ChromeUtils.importESModule(
+    "resource://testing-common/dom/quota/test/modules/WorkerDriver.sys.mjs"
+  );
+
+  const base = "resource://testing-common/dom/fs/test/xpcshell/";
+
+  const listener = {
+    onOk(value, message) {
+      ok(value, message);
+    },
+    onIs(a, b, message) {
+      Assert.equal(a, b, message);
+    },
+    onInfo(message) {
+      info(message);
+    },
+  };
+
+  await runTestInWorker(script, base, listener);
+}
+
+add_setup(async function () {
+  const {
+    setStoragePrefs,
+    clearStoragePrefs,
+    clearStoragesForOrigin,
+    resetStorage,
+  } = ChromeUtils.importESModule(
+    "resource://testing-common/dom/quota/test/modules/StorageUtils.sys.mjs"
+  );
+
+  const optionalPrefsToSet = [
+    ["dom.fs.enabled", true],
+    ["dom.fs.writable_file_stream.enabled", true],
+  ];
+
+  setStoragePrefs(optionalPrefsToSet);
+
+  registerCleanupFunction(async function () {
+    const principal = Cc["@mozilla.org/systemprincipal;1"].createInstance(
+      Ci.nsIPrincipal
+    );
+
+    await clearStoragesForOrigin(principal);
+
+    Services.prefs.clearUserPref(
+      "dom.quotaManager.temporaryStorage.fixedLimit"
+    );
+
+    await resetStorage();
+
+    const optionalPrefsToClear = [
+      "dom.fs.enabled",
+      "dom.fs.writable_file_stream.enabled",
+    ];
+
+    clearStoragePrefs(optionalPrefsToClear);
+  });
+
+  do_get_profile();
+});
diff --git a/dom/fs/test/xpcshell/moz.build b/dom/fs/test/xpcshell/moz.build
new file mode 100644
index 0000000000..f18cc1c466
--- /dev/null
+++ b/dom/fs/test/xpcshell/moz.build
@@ -0,0 +1,13 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+TEST_DIRS += [
+    "worker",
+]
+
+XPCSHELL_TESTS_MANIFESTS += [
+    "xpcshell.toml",
+]
diff --git a/dom/fs/test/xpcshell/test_basics.js b/dom/fs/test/xpcshell/test_basics.js
new file mode 100644
index 0000000000..9c70eaceb3
--- /dev/null
+++ b/dom/fs/test/xpcshell/test_basics.js
@@ -0,0 +1,14 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+add_task(async function init() {
+  const testSet = "dom/fs/test/common/test_basics.js";
+
+  const testCases = await require_module(testSet);
+
+  Object.values(testCases).forEach(testItem => {
+    add_task(testItem);
+  });
+});
diff --git a/dom/fs/test/xpcshell/test_basics_worker.js b/dom/fs/test/xpcshell/test_basics_worker.js
new file mode 100644
index 0000000000..4569a6a88c
--- /dev/null
+++ b/dom/fs/test/xpcshell/test_basics_worker.js
@@ -0,0 +1,8 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+add_task(async function worker() {
+  await run_test_in_worker("worker/test_basics_worker.js");
+});
diff --git a/dom/fs/test/xpcshell/test_fileSystemDirectoryHandle.js b/dom/fs/test/xpcshell/test_fileSystemDirectoryHandle.js
new file mode 100644
index 0000000000..6349d9aab8
--- /dev/null
+++ b/dom/fs/test/xpcshell/test_fileSystemDirectoryHandle.js
@@ -0,0 +1,14 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+add_task(async function init() {
+  const testSet = "dom/fs/test/common/test_fileSystemDirectoryHandle.js";
+
+  const testCases = await require_module(testSet);
+
+  Object.values(testCases).forEach(testItem => {
+    add_task(testItem);
+  });
+});
diff --git a/dom/fs/test/xpcshell/test_fileSystemDirectoryHandle_worker.js b/dom/fs/test/xpcshell/test_fileSystemDirectoryHandle_worker.js
new file mode 100644
index 0000000000..524b7352b4
--- /dev/null
+++ b/dom/fs/test/xpcshell/test_fileSystemDirectoryHandle_worker.js
@@ -0,0 +1,8 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+add_task(async function worker() {
+  await run_test_in_worker("worker/test_fileSystemDirectoryHandle_worker.js");
+});
diff --git a/dom/fs/test/xpcshell/test_syncAccessHandle_worker.js b/dom/fs/test/xpcshell/test_syncAccessHandle_worker.js
new file mode 100644
index 0000000000..377efab598
--- /dev/null
+++ b/dom/fs/test/xpcshell/test_syncAccessHandle_worker.js
@@ -0,0 +1,8 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+add_task(async function worker() {
+  await run_test_in_worker("worker/test_syncAccessHandle_worker.js");
+});
diff --git a/dom/fs/test/xpcshell/test_writableFileStream.js b/dom/fs/test/xpcshell/test_writableFileStream.js
new file mode 100644
index 0000000000..1ac9fdb793
--- /dev/null
+++ b/dom/fs/test/xpcshell/test_writableFileStream.js
@@ -0,0 +1,14 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+add_task(async function init() {
+  const testSet = "dom/fs/test/common/test_writableFileStream.js";
+
+  const testCases = await require_module(testSet);
+
+  Object.values(testCases).forEach(testItem => {
+    add_task(testItem);
+  });
+});
diff --git a/dom/fs/test/xpcshell/test_writableFileStream_worker.js b/dom/fs/test/xpcshell/test_writableFileStream_worker.js
new file mode 100644
index 0000000000..879ca6c0ca
--- /dev/null
+++ b/dom/fs/test/xpcshell/test_writableFileStream_worker.js
@@ -0,0 +1,8 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+add_task(async function worker() {
+  await run_test_in_worker("worker/test_writableFileStream_worker.js");
+});
diff --git a/dom/fs/test/xpcshell/worker/.eslintrc.js b/dom/fs/test/xpcshell/worker/.eslintrc.js
new file mode 100644
index 0000000000..93bf938654
--- /dev/null
+++ b/dom/fs/test/xpcshell/worker/.eslintrc.js
@@ -0,0 +1,12 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+"use strict";
+
+module.exports = {
+  env: {
+    worker: true,
+  },
+};
diff --git a/dom/fs/test/xpcshell/worker/dummy.js b/dom/fs/test/xpcshell/worker/dummy.js
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/dom/fs/test/xpcshell/worker/dummy.js
diff --git a/dom/fs/test/xpcshell/worker/head.js b/dom/fs/test/xpcshell/worker/head.js
new file mode 100644
index 0000000000..06a779841f
--- /dev/null
+++ b/dom/fs/test/xpcshell/worker/head.js
@@ -0,0 +1,22 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+async function require_module(id) {
+  if (!require_module.moduleLoader) {
+    importScripts("/dom/quota/test/modules/worker/ModuleLoader.js");
+
+    const base = location.href;
+
+    const depth = "../../../../../";
+
+    importScripts("/dom/quota/test/modules/worker/Assert.js");
+
+    importScripts("/dom/quota/test/modules/worker/Utils.js");
+
+    require_module.moduleLoader = new globalThis.ModuleLoader(base, depth);
+  }
+
+  return require_module.moduleLoader.require(id);
+}
diff --git a/dom/fs/test/xpcshell/worker/moz.build b/dom/fs/test/xpcshell/worker/moz.build
new file mode 100644
index 0000000000..c0230d1927
--- /dev/null
+++ b/dom/fs/test/xpcshell/worker/moz.build
@@ -0,0 +1,13 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+TESTING_JS_MODULES.dom.fs.test.xpcshell.worker += [
+    "head.js",
+    "test_basics_worker.js",
+    "test_fileSystemDirectoryHandle_worker.js",
+    "test_syncAccessHandle_worker.js",
+    "test_writableFileStream_worker.js",
+]
diff --git a/dom/fs/test/xpcshell/worker/test_basics_worker.js b/dom/fs/test/xpcshell/worker/test_basics_worker.js
new file mode 100644
index 0000000000..e4a4958071
--- /dev/null
+++ b/dom/fs/test/xpcshell/worker/test_basics_worker.js
@@ -0,0 +1,11 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+add_task(async function init() {
+  const testCases = await require_module("dom/fs/test/common/test_basics.js");
+  Object.values(testCases).forEach(async testItem => {
+    add_task(testItem);
+  });
+});
diff --git a/dom/fs/test/xpcshell/worker/test_fileSystemDirectoryHandle_worker.js b/dom/fs/test/xpcshell/worker/test_fileSystemDirectoryHandle_worker.js
new file mode 100644
index 0000000000..d4ba0b387c
--- /dev/null
+++ b/dom/fs/test/xpcshell/worker/test_fileSystemDirectoryHandle_worker.js
@@ -0,0 +1,13 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+add_task(async function init() {
+  const testCases = await require_module(
+    "dom/fs/test/common/test_fileSystemDirectoryHandle.js"
+  );
+  Object.values(testCases).forEach(async testItem => {
+    add_task(testItem);
+  });
+});
diff --git a/dom/fs/test/xpcshell/worker/test_syncAccessHandle_worker.js b/dom/fs/test/xpcshell/worker/test_syncAccessHandle_worker.js
new file mode 100644
index 0000000000..e6c6a96143
--- /dev/null
+++ b/dom/fs/test/xpcshell/worker/test_syncAccessHandle_worker.js
@@ -0,0 +1,13 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+add_task(async function init() {
+  const testCases = await require_module(
+    "dom/fs/test/common/test_syncAccessHandle.js"
+  );
+  Object.values(testCases).forEach(async testItem => {
+    add_task(testItem);
+  });
+});
diff --git a/dom/fs/test/xpcshell/worker/test_writableFileStream_worker.js b/dom/fs/test/xpcshell/worker/test_writableFileStream_worker.js
new file mode 100644
index 0000000000..1e9bb12ae8
--- /dev/null
+++ b/dom/fs/test/xpcshell/worker/test_writableFileStream_worker.js
@@ -0,0 +1,13 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+add_task(async function init() {
+  const testCases = await require_module(
+    "dom/fs/test/common/test_writableFileStream.js"
+  );
+  Object.values(testCases).forEach(async testItem => {
+    add_task(testItem);
+  });
+});
diff --git a/dom/fs/test/xpcshell/xpcshell.toml b/dom/fs/test/xpcshell/xpcshell.toml
new file mode 100644
index 0000000000..564c4f819b
--- /dev/null
+++ b/dom/fs/test/xpcshell/xpcshell.toml
@@ -0,0 +1,16 @@
+[DEFAULT]
+head = "head.js"
+
+["test_basics.js"]
+
+["test_basics_worker.js"]
+
+["test_fileSystemDirectoryHandle.js"]
+
+["test_fileSystemDirectoryHandle_worker.js"]
+
+["test_syncAccessHandle_worker.js"]
+
+["test_writableFileStream.js"]
+
+["test_writableFileStream_worker.js"]