1 files changed, 106 insertions, 0 deletions
diff --git a/dom/fs/test/common/test_writableFileStream.js b/dom/fs/test/common/test_writableFileStream.js
index 016c53bf3b..5b6caa0d20 100644
--- a/dom/fs/test/common/test_writableFileStream.js
+++ b/dom/fs/test/common/test_writableFileStream.js
@@ -2,6 +2,7 @@
    http://creativecommons.org/publicdomain/zero/1.0/ */
 
 const allowCreate = { create: true };
+const denyCreate = { create: false };
 
 exported_symbols.test0 = async function () {
   let root = await navigator.storage.getDirectory();
@@ -145,6 +146,111 @@ exported_symbols.bug1825018 = async function () {
   }
 };
 
+exported_symbols.usageTest = async function () {
+  const bufferSize = 1024;
+  const keepData = { keepExistingData: true };
+  const fromEmpty = { keepExistingData: false };
+
+  let root = await navigator.storage.getDirectory();
+  Assert.ok(root, "Can we access the root directory?");
+
+  const baseUsage = await Utils.getCachedOriginUsage();
+  Assert.ok(true, "Usage " + baseUsage);
+  // Create a file.
+  {
+    const fileHandle = await root.getFileHandle("usagetest.txt", allowCreate);
+    Assert.ok(!!fileHandle, "Can we get file handle?");
+
+    const writable = await fileHandle.createWritable(fromEmpty);
+    Assert.ok(!!writable, "Can we create writable file stream?");
+
+    const buffer = new ArrayBuffer(bufferSize);
+    Assert.ok(!!buffer, "Can we create array buffer?");
+
+    const result = await writable.write(buffer);
+    Assert.equal(result, undefined, "Can we write entire buffer?");
+
+    await writable.close();
+  }
+
+  {
+    const fileUsage = await Utils.getCachedOriginUsage();
+    Assert.ok(true, "Usage " + fileUsage);
+    Assert.ok(fileUsage >= baseUsage + bufferSize);
+
+    const fileHandle = await root.getFileHandle("usagetest.txt", denyCreate);
+    Assert.ok(!!fileHandle, "Can we get file handle?");
+
+    {
+      const usageNow = await Utils.getCachedOriginUsage();
+      Assert.equal(usageNow, fileUsage);
+    }
+
+    const writableA = await fileHandle.createWritable(keepData);
+    Assert.ok(!!writableA, "Can we create writable file stream?");
+
+    {
+      const usageNow = await Utils.getCachedOriginUsage();
+      Assert.ok(true, "Usage " + usageNow.usage);
+      Assert.equal(usageNow, fileUsage + bufferSize);
+    }
+
+    const writableB = await fileHandle.createWritable(keepData);
+    Assert.ok(!!writableB, "Can we create writable file stream?");
+
+    {
+      const usageNow = await Utils.getCachedOriginUsage();
+      Assert.equal(usageNow, fileUsage + 2 * bufferSize);
+    }
+
+    const writableC = await fileHandle.createWritable(keepData);
+    Assert.ok(!!writableC, "Can we create writable file stream?");
+
+    {
+      const usageNow = await Utils.getCachedOriginUsage();
+      Assert.equal(usageNow, fileUsage + 3 * bufferSize);
+    }
+
+    const writableD = await fileHandle.createWritable(fromEmpty);
+    Assert.ok(!!writableD, "Can we create writable file stream?");
+
+    {
+      const usageNow = await Utils.getCachedOriginUsage();
+      // We did not keep existing data for this writable
+      Assert.equal(usageNow, fileUsage + 3 * bufferSize);
+    }
+
+    await writableA.abort();
+
+    {
+      const usageNow = await Utils.getCachedOriginUsage();
+      Assert.equal(usageNow, fileUsage + 2 * bufferSize);
+    }
+
+    await writableB.close();
+
+    {
+      const usageNow = await Utils.getCachedOriginUsage();
+      Assert.equal(usageNow, fileUsage + bufferSize);
+    }
+
+    await writableC.abort();
+
+    {
+      const usageNow = await Utils.getCachedOriginUsage();
+      Assert.equal(usageNow, fileUsage);
+    }
+
+    await writableD.close();
+
+    {
+      const usageNow = await Utils.getCachedOriginUsage();
+      // Buffer was overwritten with nothing.
+      Assert.equal(usageNow, fileUsage - bufferSize);
+    }
+  }
+};
+
 for (const [key, value] of Object.entries(exported_symbols)) {
   Object.defineProperty(value, "name", {
     value: key,