Adding upstream version 115.7.0esr.upstream/115.7.0esr

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

45 files changed, 2249 insertions, 0 deletions

diff --git a/devtools/client/jsonview/test/array_json.json b/devtools/client/jsonview/test/array_json.json
new file mode 100644
index 0000000000..a53a19fa70
--- /dev/null
+++ b/devtools/client/jsonview/test/array_json.json
@@ -0,0 +1 @@
+[{ "name": "jan" }, { "name": "honza" }, { "name": "odvarko" }]
diff --git a/devtools/client/jsonview/test/array_json.json^headers^ b/devtools/client/jsonview/test/array_json.json^headers^
new file mode 100644
index 0000000000..6010bfd188
--- /dev/null
+++ b/devtools/client/jsonview/test/array_json.json^headers^
@@ -0,0 +1 @@
+Content-Type: application/json; charset=utf-8
diff --git a/devtools/client/jsonview/test/browser.ini b/devtools/client/jsonview/test/browser.ini
new file mode 100644
index 0000000000..0acb44c6b3
--- /dev/null
+++ b/devtools/client/jsonview/test/browser.ini
@@ -0,0 +1,59 @@
+[DEFAULT]
+tags = devtools
+subsuite = devtools
+support-files =
+  array_json.json
+  array_json.json^headers^
+  csp_json.json
+  csp_json.json^headers^
+  empty.html
+  head.js
+  invalid_json.json
+  invalid_json.json^headers^
+  manifest_json.json
+  manifest_json.json^headers^
+  passthrough-sw.js
+  simple_json.json
+  simple_json.json^headers^
+  valid_json.json
+  valid_json.json^headers^
+  !/devtools/client/framework/test/head.js
+  !/devtools/client/shared/test/shared-head.js
+  !/devtools/client/shared/test/telemetry-test-helpers.js
+
+[browser_json_refresh.js]
+[browser_jsonview_bug_1380828.js]
+[browser_jsonview_chunked_json.js]
+skip-if = http3 # Bug 1829298
+support-files =
+  chunked_json.sjs
+[browser_jsonview_content_type.js]
+[browser_jsonview_copy_headers.js]
+[browser_jsonview_copy_json.js]
+[browser_jsonview_copy_rawdata.js]
+[browser_jsonview_csp_json.js]
+[browser_jsonview_data_blocking.js]
+[browser_jsonview_empty_object.js]
+[browser_jsonview_encoding.js]
+[browser_jsonview_filter.js]
+[browser_jsonview_filter_clear.js]
+[browser_jsonview_ignore_charset.js]
+[browser_jsonview_initial_focus.js]
+[browser_jsonview_invalid_json.js]
+[browser_jsonview_manifest.js]
+[browser_jsonview_nojs.js]
+[browser_jsonview_nul.js]
+[browser_jsonview_object-type.js]
+[browser_jsonview_row_selection.js]
+[browser_jsonview_save_json.js]
+skip-if = http3 # Bug 1829298
+support-files =
+  !/toolkit/content/tests/browser/common/mockTransfer.js
+[browser_jsonview_serviceworker.js]
+[browser_jsonview_slash.js]
+[browser_jsonview_theme.js]
+[browser_jsonview_url_linkification.js]
+[browser_jsonview_valid_json.js]
+[browser_jsonview_expand_collapse.js]
+skip-if =
+  os == 'linux' && bits == 64 && !debug # Bug 1794904
diff --git a/devtools/client/jsonview/test/browser_json_refresh.js b/devtools/client/jsonview/test/browser_json_refresh.js
new file mode 100644
index 0000000000..0fbebbae57
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_json_refresh.js
@@ -0,0 +1,97 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const TEST_JSON_FILE = "simple_json.json";
+
+add_task(async function () {
+  info("Test JSON refresh started");
+
+  // generate file:// URI for JSON file and load in new tab
+  const dir = getChromeDir(getResolvedURI(gTestPath));
+  dir.append(TEST_JSON_FILE);
+  dir.normalize();
+  const uri = Services.io.newFileURI(dir);
+  const tab = await addJsonViewTab(uri.spec);
+
+  // perform sanity checks for URI and principals in loadInfo
+  await SpecialPowers.spawn(
+    tab.linkedBrowser,
+    [{ TEST_JSON_FILE }],
+    // eslint-disable-next-line no-shadow
+    async function ({ TEST_JSON_FILE }) {
+      const channel = content.docShell.currentDocumentChannel;
+      const channelURI = channel.URI.spec;
+      ok(
+        channelURI.startsWith("file://") && channelURI.includes(TEST_JSON_FILE),
+        "sanity: correct channel uri"
+      );
+      const contentPolicyType = channel.loadInfo.externalContentPolicyType;
+      is(
+        contentPolicyType,
+        Ci.nsIContentPolicy.TYPE_DOCUMENT,
+        "sanity: correct contentPolicyType"
+      );
+
+      const loadingPrincipal = channel.loadInfo.loadingPrincipal;
+      is(loadingPrincipal, null, "sanity: correct loadingPrincipal");
+      const triggeringPrincipal = channel.loadInfo.triggeringPrincipal;
+      ok(
+        triggeringPrincipal.isSystemPrincipal,
+        "sanity: correct triggeringPrincipal"
+      );
+      const principalToInherit = channel.loadInfo.principalToInherit;
+      ok(
+        principalToInherit.isNullPrincipal,
+        "sanity: correct principalToInherit"
+      );
+      ok(
+        content.document.nodePrincipal.isNullPrincipal,
+        "sanity: correct doc.nodePrincipal"
+      );
+    }
+  );
+
+  // reload the tab
+  await reloadBrowser();
+
+  // check principals in loadInfo are still correct
+  await SpecialPowers.spawn(
+    tab.linkedBrowser,
+    [{ TEST_JSON_FILE }],
+    // eslint-disable-next-line no-shadow
+    async function ({ TEST_JSON_FILE }) {
+      // eslint-disable-line
+      const channel = content.docShell.currentDocumentChannel;
+      const channelURI = channel.URI.spec;
+      ok(
+        channelURI.startsWith("file://") && channelURI.includes(TEST_JSON_FILE),
+        "reloaded: correct channel uri"
+      );
+      const contentPolicyType = channel.loadInfo.externalContentPolicyType;
+      is(
+        contentPolicyType,
+        Ci.nsIContentPolicy.TYPE_DOCUMENT,
+        "reloaded: correct contentPolicyType"
+      );
+
+      const loadingPrincipal = channel.loadInfo.loadingPrincipal;
+      is(loadingPrincipal, null, "reloaded: correct loadingPrincipal");
+      const triggeringPrincipal = channel.loadInfo.triggeringPrincipal;
+      ok(
+        triggeringPrincipal.isSystemPrincipal,
+        "reloaded: correct triggeringPrincipal"
+      );
+      const principalToInherit = channel.loadInfo.principalToInherit;
+      ok(
+        principalToInherit.isNullPrincipal,
+        "reloaded: correct principalToInherit"
+      );
+      ok(
+        content.document.nodePrincipal.isNullPrincipal,
+        "reloaded: correct doc.nodePrincipal"
+      );
+    }
+  );
+});
diff --git a/devtools/client/jsonview/test/browser_jsonview_bug_1380828.js b/devtools/client/jsonview/test/browser_jsonview_bug_1380828.js
new file mode 100644
index 0000000000..6d698e8930
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_bug_1380828.js
@@ -0,0 +1,32 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const VALID_JSON_URL = URL_ROOT + "valid_json.json";
+const INVALID_JSON_URL = URL_ROOT + "invalid_json.json";
+const prettyPrintButtonClass = ".textPanelBox .toolbar button.prettyprint";
+
+add_task(async function () {
+  info("Test 'Pretty Print' button disappears on parsing invalid JSON");
+
+  const count = await testPrettyPrintButton(INVALID_JSON_URL);
+  is(count, 0, "There must be no pretty-print button for invalid json");
+});
+
+add_task(async function () {
+  info("Test 'Pretty Print' button is present on parsing valid JSON");
+
+  const count = await testPrettyPrintButton(VALID_JSON_URL);
+  is(count, 1, "There must be pretty-print button for valid json");
+});
+
+async function testPrettyPrintButton(url) {
+  await addJsonViewTab(url);
+
+  await selectJsonViewContentTab("rawdata");
+  info("Switched to Raw Data tab.");
+
+  const count = await getElementCount(prettyPrintButtonClass);
+  return count;
+}
diff --git a/devtools/client/jsonview/test/browser_jsonview_chunked_json.js b/devtools/client/jsonview/test/browser_jsonview_chunked_json.js
new file mode 100644
index 0000000000..56fe611486
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_chunked_json.js
@@ -0,0 +1,121 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const TEST_JSON_URL = URL_ROOT_SSL + "chunked_json.sjs";
+
+add_task(async function () {
+  info("Test chunked JSON started");
+
+  await addJsonViewTab(TEST_JSON_URL, {
+    appReadyState: "interactive",
+    docReadyState: "loading",
+  });
+
+  is(
+    await getElementCount(".rawdata.is-active"),
+    1,
+    "The Raw Data tab is selected."
+  );
+
+  // Write some text and check that it is displayed.
+  await write("[");
+  await checkText();
+
+  // Repeat just in case.
+  await write("1,");
+  await checkText();
+
+  is(
+    await getElementCount("button.prettyprint"),
+    0,
+    "There is no pretty print button during load"
+  );
+
+  await selectJsonViewContentTab("json");
+  is(
+    await getElementText(".jsonPanelBox > .panelContent"),
+    "",
+    "There is no JSON tree"
+  );
+
+  await selectJsonViewContentTab("headers");
+  ok(
+    await getElementText(".headersPanelBox .netInfoHeadersTable"),
+    "The headers table has been filled."
+  );
+
+  // Write some text without being in Raw Data, then switch tab and check.
+  await write("2");
+  await selectJsonViewContentTab("rawdata");
+  await checkText();
+
+  // Add an array, when counting rows we will ensure it has been expanded automatically.
+  await write(",[3]]");
+  await checkText();
+
+  // Close the connection.
+
+  // When the ready state of the JSON View app changes, it triggers the
+  // custom event "AppReadyStateChange".
+  const appReady = BrowserTestUtils.waitForContentEvent(
+    gBrowser.selectedBrowser,
+    "AppReadyStateChange",
+    true,
+    null,
+    true
+  );
+  await server("close");
+  await appReady;
+
+  is(await getElementCount(".json.is-active"), 1, "The JSON tab is selected.");
+
+  is(
+    await getElementCount(".jsonPanelBox .treeTable .treeRow"),
+    4,
+    "There is a tree with 4 rows."
+  );
+
+  await selectJsonViewContentTab("rawdata");
+  await checkText();
+
+  is(
+    await getElementCount("button.prettyprint"),
+    1,
+    "There is a pretty print button."
+  );
+  await clickJsonNode("button.prettyprint");
+  await checkText(JSON.stringify(JSON.parse(data), null, 2));
+});
+
+let data = " ";
+async function write(text) {
+  data += text;
+  const onJsonViewUpdated = SpecialPowers.spawn(
+    gBrowser.selectedBrowser,
+    [],
+    () => {
+      return new Promise(resolve => {
+        const observer = new content.MutationObserver(() => resolve());
+        observer.observe(content.wrappedJSObject.JSONView.json, {
+          characterData: true,
+        });
+      });
+    }
+  );
+  await server("write", text);
+  await onJsonViewUpdated;
+}
+async function checkText(text = data) {
+  is(await getElementText(".textPanelBox .data"), text, "Got the right text.");
+}
+
+function server(action, value) {
+  return new Promise(resolve => {
+    const xhr = new XMLHttpRequest();
+    xhr.open("GET", TEST_JSON_URL + "?" + action + "=" + value);
+    xhr.addEventListener("load", resolve, { once: true });
+    xhr.send();
+  });
+}
diff --git a/devtools/client/jsonview/test/browser_jsonview_content_type.js b/devtools/client/jsonview/test/browser_jsonview_content_type.js
new file mode 100644
index 0000000000..c3298cc7d9
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_content_type.js
@@ -0,0 +1,100 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const mimeSvc = Cc["@mozilla.org/mime;1"].getService(Ci.nsIMIMEService);
+const handlerSvc = Cc["@mozilla.org/uriloader/handler-service;1"].getService(
+  Ci.nsIHandlerService
+);
+
+const contentTypes = {
+  valid: [
+    "application/json",
+    "application/manifest+json",
+    "application/vnd.api+json",
+    "application/hal+json",
+    "application/json+json",
+    "application/whatever+json",
+  ],
+  invalid: [
+    "text/json",
+    "text/hal+json",
+    "application/jsona",
+    "application/whatever+jsona",
+  ],
+};
+
+add_task(async function () {
+  info("Test JSON content types started");
+
+  // Prevent saving files to disk.
+  const useDownloadDir = SpecialPowers.getBoolPref(
+    "browser.download.useDownloadDir"
+  );
+  SpecialPowers.setBoolPref("browser.download.useDownloadDir", false);
+  const { MockFilePicker } = SpecialPowers;
+  MockFilePicker.init(window);
+  MockFilePicker.returnValue = MockFilePicker.returnCancel;
+
+  for (const kind of Object.keys(contentTypes)) {
+    const isValid = kind === "valid";
+    for (const type of contentTypes[kind]) {
+      // Prevent "Open or Save" dialogs, which would make the test fail.
+      const mimeInfo = mimeSvc.getFromTypeAndExtension(type, null);
+      const exists = handlerSvc.exists(mimeInfo);
+      const { alwaysAskBeforeHandling } = mimeInfo;
+      mimeInfo.alwaysAskBeforeHandling = false;
+      handlerSvc.store(mimeInfo);
+
+      await testType(isValid, type);
+      await testType(isValid, type, ";foo=bar+json");
+
+      // Restore old nsIMIMEInfo
+      if (exists) {
+        Object.assign(mimeInfo, { alwaysAskBeforeHandling });
+        handlerSvc.store(mimeInfo);
+      } else {
+        handlerSvc.remove(mimeInfo);
+      }
+    }
+  }
+
+  // Restore old pref
+  registerCleanupFunction(function () {
+    MockFilePicker.cleanup();
+    SpecialPowers.setBoolPref(
+      "browser.download.useDownloadDir",
+      useDownloadDir
+    );
+  });
+});
+
+function testType(isValid, type, params = "") {
+  const TEST_JSON_URL = "data:" + type + params + ",[1,2,3]";
+  return addJsonViewTab(TEST_JSON_URL).then(
+    async function () {
+      ok(isValid, "The JSON Viewer should only load for valid content types.");
+      await SpecialPowers.spawn(
+        gBrowser.selectedBrowser,
+        [type],
+        function (contentType) {
+          is(
+            content.document.contentType,
+            contentType,
+            "Got the right content type"
+          );
+        }
+      );
+
+      const count = await getElementCount(".jsonPanelBox .treeTable .treeRow");
+      is(count, 3, "There must be expected number of rows");
+    },
+    function () {
+      ok(
+        !isValid,
+        "The JSON Viewer should only not load for invalid content types."
+      );
+    }
+  );
+}
diff --git a/devtools/client/jsonview/test/browser_jsonview_copy_headers.js b/devtools/client/jsonview/test/browser_jsonview_copy_headers.js
new file mode 100644
index 0000000000..faa6e43354
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_copy_headers.js
@@ -0,0 +1,38 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const TEST_JSON_URL = URL_ROOT + "valid_json.json";
+
+add_task(async function () {
+  info("Test valid JSON started");
+
+  await addJsonViewTab(TEST_JSON_URL);
+
+  // Select the RawData tab
+  await selectJsonViewContentTab("headers");
+
+  // Check displayed headers
+  const count = await getElementCount(".headersPanelBox .netHeadersGroup");
+  is(count, 2, "There must be two header groups");
+
+  const text = await getElementText(".headersPanelBox .netInfoHeadersTable");
+  isnot(text, "", "Headers text must not be empty");
+
+  const browser = gBrowser.selectedBrowser;
+
+  // Verify JSON copy into the clipboard.
+  await waitForClipboardPromise(
+    function setup() {
+      BrowserTestUtils.synthesizeMouseAtCenter(
+        ".headersPanelBox .toolbar button.copy",
+        {},
+        browser
+      );
+    },
+    function validator(value) {
+      return value.indexOf("application/json") > 0;
+    }
+  );
+});
diff --git a/devtools/client/jsonview/test/browser_jsonview_copy_json.js b/devtools/client/jsonview/test/browser_jsonview_copy_json.js
new file mode 100644
index 0000000000..56c7b3ff75
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_copy_json.js
@@ -0,0 +1,34 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const TEST_JSON_URL = URL_ROOT + "simple_json.json";
+
+add_task(async function () {
+  info("Test copy JSON started");
+
+  await addJsonViewTab(TEST_JSON_URL);
+
+  const countBefore = await getElementCount(
+    ".jsonPanelBox .treeTable .treeRow"
+  );
+  ok(countBefore == 1, "There must be one row");
+
+  const text = await getElementText(".jsonPanelBox .treeTable .treeRow");
+  is(text, 'name"value"', "There must be proper JSON displayed");
+
+  // Verify JSON copy into the clipboard.
+  const value = '{ "name": "value" }\n';
+  const browser = gBrowser.selectedBrowser;
+  const selector = ".jsonPanelBox .toolbar button.copy";
+  await waitForClipboardPromise(
+    function setup() {
+      BrowserTestUtils.synthesizeMouseAtCenter(selector, {}, browser);
+    },
+    function validator(result) {
+      const str = normalizeNewLines(result);
+      return str == value;
+    }
+  );
+});
diff --git a/devtools/client/jsonview/test/browser_jsonview_copy_rawdata.js b/devtools/client/jsonview/test/browser_jsonview_copy_rawdata.js
new file mode 100644
index 0000000000..0685b7c5d3
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_copy_rawdata.js
@@ -0,0 +1,62 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const TEST_JSON_URL = URL_ROOT + "simple_json.json";
+
+const jsonText = '{ "name": "value" }\n';
+const prettyJson = '{\n  "name": "value"\n}';
+
+add_task(async function () {
+  info("Test copy raw data started");
+
+  await addJsonViewTab(TEST_JSON_URL);
+
+  // Select the RawData tab
+  await selectJsonViewContentTab("rawdata");
+
+  // Check displayed JSON
+  const text = await getElementText(".textPanelBox .data");
+  is(text, jsonText, "Proper JSON must be displayed in DOM");
+
+  const browser = gBrowser.selectedBrowser;
+
+  // Verify JSON copy into the clipboard.
+  await waitForClipboardPromise(function setup() {
+    BrowserTestUtils.synthesizeMouseAtCenter(
+      ".textPanelBox .toolbar button.copy",
+      {},
+      browser
+    );
+  }, jsonText);
+
+  // Click 'Pretty Print' button
+  await BrowserTestUtils.synthesizeMouseAtCenter(
+    ".textPanelBox .toolbar button.prettyprint",
+    {},
+    browser
+  );
+
+  let prettyText = await getElementText(".textPanelBox .data");
+  prettyText = normalizeNewLines(prettyText);
+  ok(
+    prettyText.startsWith(prettyJson),
+    "Pretty printed JSON must be displayed"
+  );
+
+  // Verify JSON copy into the clipboard.
+  await waitForClipboardPromise(
+    function setup() {
+      BrowserTestUtils.synthesizeMouseAtCenter(
+        ".textPanelBox .toolbar button.copy",
+        {},
+        browser
+      );
+    },
+    function validator(value) {
+      const str = normalizeNewLines(value);
+      return str == prettyJson;
+    }
+  );
+});
diff --git a/devtools/client/jsonview/test/browser_jsonview_csp_json.js b/devtools/client/jsonview/test/browser_jsonview_csp_json.js
new file mode 100644
index 0000000000..4416bccf15
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_csp_json.js
@@ -0,0 +1,33 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const TEST_JSON_URL = URL_ROOT + "csp_json.json";
+
+add_task(async function () {
+  info("Test CSP JSON started");
+
+  const tab = await addJsonViewTab(TEST_JSON_URL);
+
+  const count = await getElementCount(".jsonPanelBox .treeTable .treeRow");
+  is(count, 1, "There must be one row");
+
+  // The JSON Viewer alters the CSP, but the displayed header should be the original one
+  await selectJsonViewContentTab("headers");
+  await SpecialPowers.spawn(tab.linkedBrowser, [], async function () {
+    const responseHeaders = content.document.querySelector(".netHeadersGroup");
+    const names = responseHeaders.querySelectorAll(".netInfoParamName");
+    let found = false;
+    for (const name of names) {
+      if (name.textContent.toLowerCase() == "content-security-policy") {
+        ok(!found, "The CSP header only appears once");
+        found = true;
+        const value = name.nextElementSibling.textContent;
+        const expected = "default-src 'none'; base-uri 'none';";
+        is(value, expected, "The CSP value has not been altered");
+      }
+    }
+    ok(found, "The CSP header is present");
+  });
+});
diff --git a/devtools/client/jsonview/test/browser_jsonview_data_blocking.js b/devtools/client/jsonview/test/browser_jsonview_data_blocking.js
new file mode 100644
index 0000000000..f36d39dcc8
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_data_blocking.js
@@ -0,0 +1,174 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const TEST_PATH = getRootDirectory(gTestPath).replace(
+  "chrome://mochitests/content",
+  "http://example.com"
+);
+
+const JSON_VIEW_MIME_TYPE = "application/vnd.mozilla.json.view";
+const nullP = Services.scriptSecurityManager.createNullPrincipal({});
+
+// We need 3 levels of nesting just to get to run something against a content
+// page, so the devtools limit of 4 levels of nesting don't help:
+/* eslint max-nested-callbacks: 0 */
+
+/**
+ * Check that we don't expose a JSONView object on data: URI windows where
+ * we block the load.
+ */
+add_task(async function test_blocked_data_exposure() {
+  await SpecialPowers.pushPrefEnv({
+    set: [["security.data_uri.block_toplevel_data_uri_navigations", true]],
+  });
+  await BrowserTestUtils.withNewTab(TEST_PATH + "empty.html", async browser => {
+    const tabCount = gBrowser.tabs.length;
+    await SpecialPowers.spawn(browser, [], function () {
+      content.w = content.window.open(
+        "data:application/vnd.mozilla.json.view,1",
+        "_blank"
+      );
+      ok(
+        !Cu.waiveXrays(content.w).JSONView,
+        "Should not have created a JSON View object"
+      );
+      // We need to wait for the JSON view machinery to actually have a chance to run.
+      // We have no way to detect that it has or hasn't, so a setTimeout is the best we
+      // can do, unfortunately.
+      return new Promise(resolve => {
+        content.setTimeout(function () {
+          // Putting the resolve before the check to avoid JS errors potentially causing
+          // the test to time out.
+          resolve();
+          ok(
+            !Cu.waiveXrays(content.w).JSONView,
+            "Should still not have a JSON View object"
+          );
+        }, 1000);
+      });
+    });
+    // Without this, if somehow the data: protocol blocker stops working, the
+    // test would just keep passing.
+    is(
+      tabCount,
+      gBrowser.tabs.length,
+      "Haven't actually opened a new window/tab"
+    );
+  });
+});
+
+/**
+ * Check that aborted channels also abort sending data from the stream converter.
+ */
+add_task(async function test_converter_abort_should_stop_data_sending() {
+  const loadInfo = NetUtil.newChannel({
+    uri: Services.io.newURI("data:text/plain,"),
+    loadingPrincipal: nullP,
+    securityFlags: Ci.nsILoadInfo.SEC_ALLOW_CROSS_ORIGIN_SEC_CONTEXT_IS_NULL,
+    contentPolicyType: Ci.nsIContentPolicy.TYPE_OTHER,
+  }).loadInfo;
+  // Stub all the things.
+  const chan = {
+    QueryInterface: ChromeUtils.generateQI([
+      "nsIChannel",
+      "nsIWritablePropertyBag",
+    ]),
+    URI: Services.io.newURI("data:application/json,{}"),
+    // loadinfo is builtinclass, need to actually have one:
+    loadInfo,
+    notificationCallbacks: {
+      QueryInterface: ChromeUtils.generateQI(["nsIInterfaceRequestor"]),
+      getInterface() {
+        // We want a loadcontext here, which is also builtinclass, can't stub.
+        return docShell;
+      },
+    },
+    status: Cr.NS_OK,
+    setProperty() {},
+  };
+  let onStartFired = false;
+  const listener = {
+    QueryInterface: ChromeUtils.generateQI(["nsIStreamListener"]),
+    onStartRequest() {
+      onStartFired = true;
+      // This should force the converter to abort, too:
+      chan.status = Cr.NS_BINDING_ABORTED;
+    },
+    onDataAvailable() {
+      ok(false, "onDataAvailable should never fire");
+    },
+  };
+  const conv = Cc[
+    "@mozilla.org/streamconv;1?from=" + JSON_VIEW_MIME_TYPE + "&to=*/*"
+  ].createInstance(Ci.nsIStreamConverter);
+  conv.asyncConvertData(
+    "application/vnd.mozilla.json.view",
+    "text/html",
+    listener,
+    null
+  );
+  conv.onStartRequest(chan);
+  ok(onStartFired, "Should have fired onStartRequest");
+});
+
+/**
+ * Check that principal mismatches break things. Note that we're stubbing
+ * the window associated with the channel to be a browser window; the
+ * converter should be bailing out because the window's principal won't
+ * match the null principal to which the converter tries to reset the
+ * inheriting principal of the channel.
+ */
+add_task(async function test_converter_principal_needs_matching() {
+  const loadInfo = NetUtil.newChannel({
+    uri: Services.io.newURI("data:text/plain,"),
+    loadingPrincipal: nullP,
+    securityFlags: Ci.nsILoadInfo.SEC_ALLOW_CROSS_ORIGIN_SEC_CONTEXT_IS_NULL,
+    contentPolicyType: Ci.nsIContentPolicy.TYPE_OTHER,
+  }).loadInfo;
+  // Stub all the things.
+  const chan = {
+    QueryInterface: ChromeUtils.generateQI([
+      "nsIChannel",
+      "nsIWritablePropertyBag",
+    ]),
+    URI: Services.io.newURI("data:application/json,{}"),
+    // loadinfo is builtinclass, need to actually have one:
+    loadInfo,
+    notificationCallbacks: {
+      QueryInterface: ChromeUtils.generateQI(["nsIInterfaceRequestor"]),
+      getInterface() {
+        // We want a loadcontext here, which is also builtinclass, can't stub.
+        return docShell;
+      },
+    },
+    status: Cr.NS_OK,
+    setProperty() {},
+    cancel(arg) {
+      this.status = arg;
+    },
+  };
+  let onStartFired = false;
+  const listener = {
+    QueryInterface: ChromeUtils.generateQI(["nsIStreamListener"]),
+    onStartRequest() {
+      onStartFired = true;
+    },
+    onDataAvailable() {
+      ok(false, "onDataAvailable should never fire");
+    },
+  };
+  const conv = Cc[
+    "@mozilla.org/streamconv;1?from=" + JSON_VIEW_MIME_TYPE + "&to=*/*"
+  ].createInstance(Ci.nsIStreamConverter);
+  conv.asyncConvertData(
+    "application/vnd.mozilla.json.view",
+    "text/html",
+    listener,
+    null
+  );
+  conv.onStartRequest(chan);
+  ok(onStartFired, "Should have fired onStartRequest");
+  is(chan.status, Cr.NS_BINDING_ABORTED, "Should have been aborted.");
+});
diff --git a/devtools/client/jsonview/test/browser_jsonview_empty_object.js b/devtools/client/jsonview/test/browser_jsonview_empty_object.js
new file mode 100644
index 0000000000..af3dfbc007
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_empty_object.js
@@ -0,0 +1,48 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+function testRootObject(objExpr, summary = objExpr) {
+  return async function () {
+    info("Test JSON with root empty object " + objExpr + " started");
+
+    const TEST_JSON_URL = "data:application/json," + objExpr;
+    await addJsonViewTab(TEST_JSON_URL);
+
+    const objectText = await getElementText(".jsonPanelBox .panelContent");
+    is(objectText, summary, "The root object " + objExpr + " is visible");
+  };
+}
+
+function testNestedObject(objExpr, summary = objExpr) {
+  return async function () {
+    info("Test JSON with nested empty object " + objExpr + " started");
+
+    const TEST_JSON_URL = "data:application/json,[" + objExpr + "]";
+    await addJsonViewTab(TEST_JSON_URL);
+
+    const objectCellCount = await getElementCount(
+      ".jsonPanelBox .treeTable .objectCell"
+    );
+    is(objectCellCount, 1, "There must be one object cell");
+
+    const objectCellText = await getElementText(
+      ".jsonPanelBox .treeTable .objectCell"
+    );
+    is(objectCellText, summary, objExpr + " has a visible summary");
+
+    // Collapse auto-expanded node.
+    await clickJsonNode(".jsonPanelBox .treeTable .treeLabel");
+
+    const textAfter = await getElementText(
+      ".jsonPanelBox .treeTable .objectCell"
+    );
+    is(textAfter, summary, objExpr + " still has a visible summary");
+  };
+}
+
+add_task(testRootObject("null"));
+add_task(testNestedObject("null"));
+add_task(testNestedObject("[]"));
+add_task(testNestedObject("{}"));
diff --git a/devtools/client/jsonview/test/browser_jsonview_encoding.js b/devtools/client/jsonview/test/browser_jsonview_encoding.js
new file mode 100644
index 0000000000..be49af39d2
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_encoding.js
@@ -0,0 +1,67 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+add_task(async function () {
+  info("Test JSON encoding started");
+
+  const bom = "%EF%BB%BF"; // UTF-8 BOM
+  const tests = [
+    {
+      input: bom,
+      output: "",
+    },
+    {
+      input: "%FE%FF", // UTF-16BE BOM
+      output: "\uFFFD\uFFFD",
+    },
+    {
+      input: "%FF%FE", // UTF-16LE BOM
+      output: "\uFFFD\uFFFD",
+    },
+    {
+      input: bom + "%30",
+      output: "0",
+    },
+    {
+      input: bom + bom,
+      output: "\uFEFF",
+    },
+    {
+      input: "%00%61",
+      output: "\u0000a",
+    },
+    {
+      input: "%61%00",
+      output: "a\u0000",
+    },
+    {
+      input: "%30%FF",
+      output: "0�",
+    },
+    {
+      input: "%C3%A0",
+      output: "à",
+    },
+    {
+      input: "%E2%9D%A4",
+      output: "❤",
+    },
+    {
+      input: "%F0%9F%9A%80",
+      output: "🚀",
+    },
+  ];
+
+  for (const { input, output } of tests) {
+    info("Test decoding of " + JSON.stringify(input) + ".");
+
+    await addJsonViewTab("data:application/json," + input);
+    await selectJsonViewContentTab("rawdata");
+
+    // Check displayed data.
+    const data = await getElementText(".textPanelBox .data");
+    is(data, output, "The right data has been received.");
+  }
+});
diff --git a/devtools/client/jsonview/test/browser_jsonview_expand_collapse.js b/devtools/client/jsonview/test/browser_jsonview_expand_collapse.js
new file mode 100644
index 0000000000..6b681ff0cc
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_expand_collapse.js
@@ -0,0 +1,61 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+XPCOMUtils.defineLazyGetter(this, "jsonViewStrings", () => {
+  return Services.strings.createBundle(
+    "chrome://devtools/locale/jsonview.properties"
+  );
+});
+
+const TEST_JSON_URL = URL_ROOT + "array_json.json";
+const EXPAND_THRESHOLD = 100 * 1024;
+
+add_task(async function () {
+  info("Test expand/collapse small JSON started");
+
+  await addJsonViewTab(TEST_JSON_URL);
+
+  /* Initial sanity check */
+  const countBefore = await getElementCount(".treeRow");
+  is(countBefore, 6, "There must be six rows");
+
+  /* Test the "Collapse All" button */
+  let selector = ".jsonPanelBox .toolbar button.collapse";
+  await clickJsonNode(selector);
+  let countAfter = await getElementCount(".treeRow");
+  is(countAfter, 3, "There must be three rows");
+
+  /* Test the "Expand All" button */
+  selector = ".jsonPanelBox .toolbar button.expand";
+  is(
+    await getElementText(selector),
+    jsonViewStrings.GetStringFromName("jsonViewer.ExpandAll"),
+    "Expand button doesn't warn that the action will be slow"
+  );
+  await clickJsonNode(selector);
+  countAfter = await getElementCount(".treeRow");
+  is(countAfter, 6, "There must be six expanded rows");
+});
+
+add_task(async function () {
+  info("Test expand button for big JSON started");
+
+  const json = JSON.stringify({
+    data: Array(1e5)
+      .fill()
+      .map(x => "hoot"),
+    status: "ok",
+  });
+  ok(
+    json.length > EXPAND_THRESHOLD,
+    "The generated JSON must be larger than 100kB"
+  );
+  await addJsonViewTab("data:application/json," + json);
+  is(
+    await getElementText(".jsonPanelBox .toolbar button.expand"),
+    jsonViewStrings.GetStringFromName("jsonViewer.ExpandAllSlow"),
+    "Expand button warns that the action will be slow"
+  );
+});
diff --git a/devtools/client/jsonview/test/browser_jsonview_filter.js b/devtools/client/jsonview/test/browser_jsonview_filter.js
new file mode 100644
index 0000000000..1dd093da5b
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_filter.js
@@ -0,0 +1,27 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const TEST_JSON_URL = URL_ROOT + "array_json.json";
+
+add_task(async function () {
+  info("Test valid JSON started");
+
+  await addJsonViewTab(TEST_JSON_URL);
+
+  const count = await getElementCount(".jsonPanelBox .treeTable .treeRow");
+  is(count, 6, "There must be expected number of rows");
+
+  // XXX use proper shortcut to focus the filter box
+  // as soon as bug Bug 1178771 is fixed.
+  await sendString("h", ".jsonPanelBox .searchBox");
+
+  // The filtering is done asynchronously so, we need to wait.
+  await waitForFilter();
+
+  const hiddenCount = await getElementCount(
+    ".jsonPanelBox .treeTable .treeRow.hidden"
+  );
+  is(hiddenCount, 4, "There must be expected number of hidden rows");
+});
diff --git a/devtools/client/jsonview/test/browser_jsonview_filter_clear.js b/devtools/client/jsonview/test/browser_jsonview_filter_clear.js
new file mode 100644
index 0000000000..70ece7ee03
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_filter_clear.js
@@ -0,0 +1,85 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const TEST_JSON_URL = URL_ROOT + "array_json.json";
+const filterClearButton = "button.devtools-searchinput-clear";
+
+function clickAndWaitForFilterClear(selector) {
+  return SpecialPowers.spawn(gBrowser.selectedBrowser, [selector], sel => {
+    content.document.querySelector(sel).click();
+
+    const rows = Array.from(
+      content.document.querySelectorAll(".jsonPanelBox .treeTable .treeRow")
+    );
+
+    // If there are no hiddens rows
+    if (!rows.some(r => r.classList.contains("hidden"))) {
+      info("The view has been cleared, no need for mutationObserver");
+      return Promise.resolve();
+    }
+
+    return new Promise(resolve => {
+      // Wait until we have 0 hidden rows
+      const observer = new content.MutationObserver(function (mutations) {
+        info("New mutation ! ");
+        info(`${mutations}`);
+        for (let i = 0; i < mutations.length; i++) {
+          const mutation = mutations[i];
+          info(`type: ${mutation.type}`);
+          info(`attributeName: ${mutation.attributeName}`);
+          info(`attributeNamespace: ${mutation.attributeNamespace}`);
+          info(`oldValue: ${mutation.oldValue}`);
+          if (mutation.attributeName == "class") {
+            if (!rows.some(r => r.classList.contains("hidden"))) {
+              info("resolving mutationObserver");
+              observer.disconnect();
+              resolve();
+              break;
+            }
+          }
+        }
+      });
+
+      const parent = content.document.querySelector("tbody");
+      observer.observe(parent, { attributes: true, subtree: true });
+    });
+  });
+}
+
+add_task(async function () {
+  info("Test filter input is cleared when pressing the clear button");
+
+  await addJsonViewTab(TEST_JSON_URL);
+
+  // Type "honza" in the filter input
+  const count = await getElementCount(".jsonPanelBox .treeTable .treeRow");
+  is(count, 6, "There must be expected number of rows");
+  await sendString("honza", ".jsonPanelBox .searchBox");
+  await waitForFilter();
+
+  const filterInputValue = await getFilterInputValue();
+  is(filterInputValue, "honza", "Filter input shoud be filled");
+
+  // Check the json is filtered
+  const hiddenCount = await getElementCount(
+    ".jsonPanelBox .treeTable .treeRow.hidden"
+  );
+  is(hiddenCount, 4, "There must be expected number of hidden rows");
+
+  info("Click on the close button");
+  await clickAndWaitForFilterClear(filterClearButton);
+
+  // Check the json is not filtered and the filter input is empty
+  const newfilterInputValue = await getFilterInputValue();
+  is(newfilterInputValue, "", "Filter input should be empty");
+  const newCount = await getElementCount(
+    ".jsonPanelBox .treeTable .treeRow.hidden"
+  );
+  is(newCount, 0, "There must be expected number of rows");
+});
+
+function getFilterInputValue() {
+  return getElementAttr(".devtools-filterinput", "value");
+}
diff --git a/devtools/client/jsonview/test/browser_jsonview_ignore_charset.js b/devtools/client/jsonview/test/browser_jsonview_ignore_charset.js
new file mode 100644
index 0000000000..ffd00a35e3
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_ignore_charset.js
@@ -0,0 +1,18 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+add_task(async function () {
+  info("Test ignored charset parameter started");
+
+  const encodedChar = "%E2%9D%A4"; // In UTF-8 this is a heavy black heart
+  const result = "❤";
+  const TEST_JSON_URL = "data:application/json;charset=ANSI," + encodedChar;
+
+  await addJsonViewTab(TEST_JSON_URL);
+  await selectJsonViewContentTab("rawdata");
+
+  const text = await getElementText(".textPanelBox .data");
+  is(text, result, "The charset parameter is ignored and UTF-8 is used.");
+});
diff --git a/devtools/client/jsonview/test/browser_jsonview_initial_focus.js b/devtools/client/jsonview/test/browser_jsonview_initial_focus.js
new file mode 100644
index 0000000000..71b0623ce5
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_initial_focus.js
@@ -0,0 +1,33 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const VALID_JSON_URL = URL_ROOT + "valid_json.json";
+
+add_task(async function () {
+  info("Test focus JSON view started");
+  await addJsonViewTab(VALID_JSON_URL);
+
+  await SpecialPowers.spawn(gBrowser.selectedBrowser, [], async () => {
+    const scroller = content.document.getElementById("json-scrolling-panel");
+    ok(scroller, "Found the scrollable area");
+    is(
+      content.document.activeElement,
+      scroller,
+      "Scrollable area initially focused"
+    );
+  });
+  await reloadBrowser();
+  await SpecialPowers.spawn(gBrowser.selectedBrowser, [], async () => {
+    const scroller = await ContentTaskUtils.waitForCondition(
+      () => content.document.getElementById("json-scrolling-panel"),
+      "Wait for the panel to be loaded"
+    );
+    is(
+      content.document.activeElement,
+      scroller,
+      "Scrollable area focused after reload"
+    );
+  });
+});
diff --git a/devtools/client/jsonview/test/browser_jsonview_invalid_json.js b/devtools/client/jsonview/test/browser_jsonview_invalid_json.js
new file mode 100644
index 0000000000..461030959b
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_invalid_json.js
@@ -0,0 +1,18 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const TEST_JSON_URL = URL_ROOT + "invalid_json.json";
+
+add_task(async function () {
+  info("Test invalid JSON started");
+
+  await addJsonViewTab(TEST_JSON_URL);
+
+  const count = await getElementCount(".jsonPanelBox .treeTable .treeRow");
+  ok(count == 0, "There must be no row");
+
+  const text = await getElementText(".jsonPanelBox .jsonParseError");
+  ok(text, "There must be an error description");
+});
diff --git a/devtools/client/jsonview/test/browser_jsonview_manifest.js b/devtools/client/jsonview/test/browser_jsonview_manifest.js
new file mode 100644
index 0000000000..8072324cf1
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_manifest.js
@@ -0,0 +1,15 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const TEST_JSON_URL = URL_ROOT + "manifest_json.json";
+
+add_task(async function () {
+  info("Test manifest JSON file started");
+
+  await addJsonViewTab(TEST_JSON_URL);
+
+  const count = await getElementCount(".jsonPanelBox .treeTable .treeRow");
+  is(count, 37, "There must be expected number of rows");
+});
diff --git a/devtools/client/jsonview/test/browser_jsonview_nojs.js b/devtools/client/jsonview/test/browser_jsonview_nojs.js
new file mode 100644
index 0000000000..38459617a2
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_nojs.js
@@ -0,0 +1,26 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+add_task(async function () {
+  info("Test JSON without JavaScript started.");
+
+  const oldPref = Services.prefs.getBoolPref("javascript.enabled");
+  Services.prefs.setBoolPref("javascript.enabled", false);
+
+  const TEST_JSON_URL = "data:application/json,[1,2,3]";
+
+  // "uninitialized" will be the last app readyState because JS is disabled.
+  await addJsonViewTab(TEST_JSON_URL, { appReadyState: "uninitialized" });
+
+  info("Checking visible text contents.");
+
+  const text = await SpecialPowers.spawn(gBrowser.selectedBrowser, [], () => {
+    const element = content.document.querySelector("html");
+    return element ? element.innerText : null;
+  });
+  is(text, "[1,2,3]", "The raw source should be visible.");
+
+  Services.prefs.setBoolPref("javascript.enabled", oldPref);
+});
diff --git a/devtools/client/jsonview/test/browser_jsonview_nul.js b/devtools/client/jsonview/test/browser_jsonview_nul.js
new file mode 100644
index 0000000000..746846796b
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_nul.js
@@ -0,0 +1,15 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+add_task(async function () {
+  info("Test JSON with NUL started.");
+
+  const TEST_JSON_URL = 'data:application/json,"foo_%00_bar"';
+  await addJsonViewTab(TEST_JSON_URL);
+
+  await selectJsonViewContentTab("rawdata");
+  const rawData = await getElementText(".textPanelBox .data");
+  is(rawData, '"foo_\u0000_bar"', "The NUL character has been preserved.");
+});
diff --git a/devtools/client/jsonview/test/browser_jsonview_object-type.js b/devtools/client/jsonview/test/browser_jsonview_object-type.js
new file mode 100644
index 0000000000..08b9ed865c
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_object-type.js
@@ -0,0 +1,25 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { ELLIPSIS } = require("resource://devtools/shared/l10n.js");
+
+add_task(async function () {
+  info("Test Object type property started");
+
+  const TEST_JSON_URL = 'data:application/json,{"x":{"type":"string"}}';
+  await addJsonViewTab(TEST_JSON_URL);
+
+  let count = await getElementCount(".jsonPanelBox .treeTable .treeRow");
+  is(count, 2, "There must be two rows");
+
+  // Collapse auto-expanded node.
+  await clickJsonNode(".jsonPanelBox .treeTable .treeLabel");
+
+  count = await getElementCount(".jsonPanelBox .treeTable .treeRow");
+  is(count, 1, "There must be one row");
+
+  const label = await getElementText(".jsonPanelBox .treeTable .objectCell");
+  is(label, `{${ELLIPSIS}}`, "The label must be indicating an object");
+});
diff --git a/devtools/client/jsonview/test/browser_jsonview_row_selection.js b/devtools/client/jsonview/test/browser_jsonview_row_selection.js
new file mode 100644
index 0000000000..300ac40a03
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_row_selection.js
@@ -0,0 +1,245 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+add_task(async function () {
+  info("Test 1 JSON row selection started");
+
+  // Create a tall JSON so that there is a scrollbar.
+  const numRows = 1e3;
+  const json = JSON.stringify(
+    Array(numRows)
+      .fill()
+      .map((_, i) => i)
+  );
+  const tab = await addJsonViewTab("data:application/json," + json);
+
+  is(
+    await getElementCount(".treeRow"),
+    numRows,
+    "Got the expected number of rows."
+  );
+  await assertRowSelected(null);
+
+  // Focus the tree and select first row.
+  await SpecialPowers.spawn(gBrowser.selectedBrowser, [], function () {
+    const tree = content.document.querySelector(".treeTable");
+    tree.focus();
+    is(tree, content.document.activeElement, "Tree should be focused");
+    content.document.querySelector(".treeRow:nth-child(1)").click();
+  });
+  await assertRowSelected(1);
+
+  await SpecialPowers.spawn(gBrowser.selectedBrowser, [], function () {
+    const scroller = content.document.querySelector(
+      ".jsonPanelBox .panelContent"
+    );
+    ok(scroller.clientHeight < scroller.scrollHeight, "There is a scrollbar.");
+    is(scroller.scrollTop, 0, "Initially scrolled to the top.");
+  });
+
+  // Select last row.
+  await BrowserTestUtils.synthesizeKey("VK_END", {}, tab.linkedBrowser);
+  await assertRowSelected(numRows);
+
+  await SpecialPowers.spawn(gBrowser.selectedBrowser, [], function () {
+    const scroller = content.document.querySelector(
+      ".jsonPanelBox .panelContent"
+    );
+    is(
+      scroller.scrollTop + scroller.clientHeight,
+      scroller.scrollHeight,
+      "Scrolled to the bottom."
+    );
+    // Click to select 2nd row.
+    content.document.querySelector(".treeRow:nth-child(2)").click();
+  });
+  await assertRowSelected(2);
+
+  await SpecialPowers.spawn(gBrowser.selectedBrowser, [], function () {
+    const scroller = content.document.querySelector(
+      ".jsonPanelBox .panelContent"
+    );
+    ok(scroller.scrollTop > 0, "Not scrolled to the top.");
+    // Synthesize up arrow key to select first row.
+    content.document.querySelector(".treeTable").focus();
+  });
+  await BrowserTestUtils.synthesizeKey("VK_UP", {}, tab.linkedBrowser);
+  await assertRowSelected(1);
+  await SpecialPowers.spawn(gBrowser.selectedBrowser, [], function () {
+    const scroller = content.document.querySelector(
+      ".jsonPanelBox .panelContent"
+    );
+    is(scroller.scrollTop, 0, "Scrolled to the top.");
+  });
+});
+
+add_task(async function () {
+  info("Test 2 JSON row selection started");
+
+  const numRows = 4;
+  const tab = await addJsonViewTab("data:application/json,[0,1,2,3]");
+
+  is(
+    await getElementCount(".treeRow"),
+    numRows,
+    "Got the expected number of rows."
+  );
+  await assertRowSelected(null);
+
+  // Click to select first row.
+  await clickJsonNode(".treeRow:first-child");
+  await assertRowSelected(1);
+
+  // Synthesize multiple down arrow keydowns to select following rows.
+  await SpecialPowers.spawn(tab.linkedBrowser, [], function () {
+    content.document.querySelector(".treeTable").focus();
+  });
+  for (let i = 2; i < numRows; ++i) {
+    await BrowserTestUtils.synthesizeKey(
+      "VK_DOWN",
+      { type: "keydown" },
+      tab.linkedBrowser
+    );
+    await assertRowSelected(i);
+  }
+
+  // Now synthesize the keyup, this shouldn't change selected row.
+  await BrowserTestUtils.synthesizeKey(
+    "VK_DOWN",
+    { type: "keyup" },
+    tab.linkedBrowser
+  );
+  await wait(500);
+  await assertRowSelected(numRows - 1);
+
+  // Finally, synthesize keydown with a modifier, this also shouldn't change selected row.
+  await BrowserTestUtils.synthesizeKey(
+    "VK_DOWN",
+    { type: "keydown", shiftKey: true },
+    tab.linkedBrowser
+  );
+  await wait(500);
+  await assertRowSelected(numRows - 1);
+});
+
+add_task(async function () {
+  info("Test 3 JSON row selection started");
+
+  // Create a JSON with a row taller than the panel.
+  const json = JSON.stringify([0, "a ".repeat(1e4), 1]);
+  const tab = await addJsonViewTab("data:application/json," + encodeURI(json));
+
+  is(await getElementCount(".treeRow"), 3, "Got the expected number of rows.");
+  await assertRowSelected(null);
+  await SpecialPowers.spawn(gBrowser.selectedBrowser, [], function () {
+    const scroller = content.document.querySelector(
+      ".jsonPanelBox .panelContent"
+    );
+    const row = content.document.querySelector(".treeRow:nth-child(2)");
+    ok(
+      scroller.clientHeight < row.clientHeight,
+      "The row is taller than the scroller."
+    );
+    is(scroller.scrollTop, 0, "Initially scrolled to the top.");
+
+    // Select the tall row.
+    content.document.querySelector(".treeTable").focus();
+    row.click();
+  });
+  await assertRowSelected(2);
+  await SpecialPowers.spawn(gBrowser.selectedBrowser, [], function () {
+    const scroller = content.document.querySelector(
+      ".jsonPanelBox .panelContent"
+    );
+    is(
+      scroller.scrollTop,
+      0,
+      "When the row is visible, do not scroll on click."
+    );
+  });
+
+  // Select the last row.
+  await BrowserTestUtils.synthesizeKey("VK_DOWN", {}, tab.linkedBrowser);
+  await assertRowSelected(3);
+  await SpecialPowers.spawn(gBrowser.selectedBrowser, [], function () {
+    const scroller = content.document.querySelector(
+      ".jsonPanelBox .panelContent"
+    );
+    is(
+      scroller.scrollTop + scroller.offsetHeight,
+      scroller.scrollHeight,
+      "Scrolled to the bottom."
+    );
+
+    // Select the tall row.
+    const row = content.document.querySelector(".treeRow:nth-child(2)");
+    row.click();
+  });
+
+  await assertRowSelected(2);
+  const scroll = await SpecialPowers.spawn(
+    gBrowser.selectedBrowser,
+    [],
+    function () {
+      const scroller = content.document.querySelector(
+        ".jsonPanelBox .panelContent"
+      );
+      const row = content.document.querySelector(".treeRow:nth-child(2)");
+      is(
+        scroller.scrollTop + scroller.offsetHeight,
+        scroller.scrollHeight,
+        "Scrolled to the bottom. When the row is visible, do not scroll on click."
+      );
+
+      // Scroll up a bit, so that both the top and bottom of the row are not visible.
+      const scrollPos = (scroller.scrollTop = Math.ceil(
+        (scroller.scrollTop + row.offsetTop) / 2
+      ));
+      ok(
+        scroller.scrollTop > row.offsetTop,
+        "The top of the row is not visible."
+      );
+      ok(
+        scroller.scrollTop + scroller.offsetHeight <
+          row.offsetTop + row.offsetHeight,
+        "The bottom of the row is not visible."
+      );
+
+      // Select the tall row.
+      row.click();
+      return scrollPos;
+    }
+  );
+
+  await assertRowSelected(2);
+  await SpecialPowers.spawn(
+    gBrowser.selectedBrowser,
+    [scroll],
+    function (scrollPos) {
+      const scroller = content.document.querySelector(
+        ".jsonPanelBox .panelContent"
+      );
+      is(scroller.scrollTop, scrollPos, "Scroll did not change");
+    }
+  );
+});
+
+async function assertRowSelected(rowNum) {
+  const idx = await SpecialPowers.spawn(
+    gBrowser.selectedBrowser,
+    [],
+    function () {
+      return [].indexOf.call(
+        content.document.querySelectorAll(".treeRow"),
+        content.document.querySelector(".treeRow.selected")
+      );
+    }
+  );
+  is(
+    idx + 1,
+    +rowNum,
+    `${rowNum ? "The row #" + rowNum : "No row"} is selected.`
+  );
+}
diff --git a/devtools/client/jsonview/test/browser_jsonview_save_json.js b/devtools/client/jsonview/test/browser_jsonview_save_json.js
new file mode 100644
index 0000000000..506967df00
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_save_json.js
@@ -0,0 +1,159 @@
+/* eslint-disable no-unused-vars, no-undef */
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const saveButton = "button.save";
+const prettifyButton = "button.prettyprint";
+
+const { MockFilePicker } = SpecialPowers;
+MockFilePicker.init(window);
+MockFilePicker.returnValue = MockFilePicker.returnOK;
+
+Services.scriptloader.loadSubScript(
+  "chrome://mochitests/content/browser/toolkit/content/tests/browser/common/mockTransfer.js",
+  this
+);
+
+function awaitSavedFileContents(name, ext) {
+  return new Promise((resolve, reject) => {
+    MockFilePicker.showCallback = fp => {
+      try {
+        ok(true, "File picker was opened");
+        const fileName = fp.defaultString;
+        is(
+          fileName,
+          name,
+          "File picker should provide the correct default filename."
+        );
+        is(
+          fp.defaultExtension,
+          ext,
+          "File picker should provide the correct default file extension."
+        );
+        const destFile = destDir.clone();
+        destFile.append(fileName);
+        MockFilePicker.setFiles([destFile]);
+        MockFilePicker.showCallback = null;
+        mockTransferCallback = async function (downloadSuccess) {
+          try {
+            ok(
+              downloadSuccess,
+              "JSON should have been downloaded successfully"
+            );
+            ok(destFile.exists(), "The downloaded file should exist.");
+            const { path } = destFile;
+            await BrowserTestUtils.waitForCondition(() => IOUtils.exists(path));
+            await BrowserTestUtils.waitForCondition(async () => {
+              const { size } = await IOUtils.stat(path);
+              return size > 0;
+            });
+            const buffer = await IOUtils.read(path);
+            resolve(new TextDecoder().decode(buffer));
+          } catch (error) {
+            reject(error);
+          }
+        };
+      } catch (error) {
+        reject(error);
+      }
+    };
+  });
+}
+
+function createTemporarySaveDirectory() {
+  const saveDir = Services.dirsvc.get("TmpD", Ci.nsIFile);
+  saveDir.append("jsonview-testsavedir");
+  if (!saveDir.exists()) {
+    info("Creating temporary save directory.");
+    saveDir.create(Ci.nsIFile.DIRECTORY_TYPE, 0o755);
+  }
+  info("Temporary save directory: " + saveDir.path);
+  return saveDir;
+}
+
+const destDir = createTemporarySaveDirectory();
+mockTransferRegisterer.register();
+MockFilePicker.displayDirectory = destDir;
+registerCleanupFunction(function () {
+  mockTransferRegisterer.unregister();
+  MockFilePicker.cleanup();
+  destDir.remove(true);
+  ok(!destDir.exists(), "Destination dir should be removed");
+});
+
+add_task(async function () {
+  info("Test 1 save JSON started");
+
+  const JSON_FILE = "simple_json.json";
+  const TEST_JSON_URL = URL_ROOT + JSON_FILE;
+  const tab = await addJsonViewTab(TEST_JSON_URL);
+
+  const response = await fetch(new Request(TEST_JSON_URL));
+
+  info("Fetched JSON contents.");
+  const rawJSON = await response.text();
+  const prettyJSON = JSON.stringify(JSON.parse(rawJSON), null, "  ");
+  isnot(
+    rawJSON,
+    prettyJSON,
+    "Original and prettified JSON should be different."
+  );
+
+  // Attempt to save original JSON via saveBrowser (ctrl/cmd+s or "Save Page As" command).
+  let data = awaitSavedFileContents(JSON_FILE, "json");
+  saveBrowser(tab.linkedBrowser);
+  is(await data, rawJSON, "Original JSON contents should have been saved.");
+
+  // Attempt to save original JSON via "Save" button
+  data = awaitSavedFileContents(JSON_FILE, "json");
+  await clickJsonNode(saveButton);
+  info("Clicked Save button.");
+  is(await data, rawJSON, "Original JSON contents should have been saved.");
+
+  // Attempt to save prettified JSON via "Save" button
+  await selectJsonViewContentTab("rawdata");
+  info("Switched to Raw Data tab.");
+  await clickJsonNode(prettifyButton);
+  info("Clicked Pretty Print button.");
+  data = awaitSavedFileContents(JSON_FILE, "json");
+  await clickJsonNode(saveButton);
+  info("Clicked Save button.");
+  is(
+    await data,
+    prettyJSON,
+    "Prettified JSON contents should have been saved."
+  );
+
+  // saveBrowser should still save original contents.
+  data = awaitSavedFileContents(JSON_FILE, "json");
+  saveBrowser(tab.linkedBrowser);
+  is(await data, rawJSON, "Original JSON contents should have been saved.");
+});
+
+add_task(async function () {
+  info("Test 2 save JSON started");
+
+  const TEST_JSON_URL = "data:application/json,2";
+  await addJsonViewTab(TEST_JSON_URL);
+
+  info("Checking that application/json adds .json extension by default.");
+  const data = awaitSavedFileContents("Untitled.json", "json");
+  await clickJsonNode(saveButton);
+  info("Clicked Save button.");
+  is(await data, "2", "JSON contents should have been saved.");
+});
+
+add_task(async function () {
+  info("Test 3 save JSON started");
+
+  const TEST_JSON_URL = "data:application/manifest+json,3";
+  await addJsonViewTab(TEST_JSON_URL);
+
+  info("Checking that application/manifest+json does not add .json extension.");
+  const data = awaitSavedFileContents("Untitled", null);
+  await clickJsonNode(saveButton);
+  info("Clicked Save button.");
+  is(await data, "3", "JSON contents should have been saved.");
+});
diff --git a/devtools/client/jsonview/test/browser_jsonview_serviceworker.js b/devtools/client/jsonview/test/browser_jsonview_serviceworker.js
new file mode 100644
index 0000000000..37c407ecd4
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_serviceworker.js
@@ -0,0 +1,89 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const TEST_JSON_URL = URL_ROOT_SSL + "valid_json.json";
+const EMPTY_PAGE = URL_ROOT_SSL + "empty.html";
+const SW = URL_ROOT_SSL + "passthrough-sw.js";
+
+add_task(async function () {
+  info("Test valid JSON with service worker started");
+
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      ["dom.serviceWorkers.exemptFromPerDomainMax", true],
+      ["dom.serviceWorkers.enabled", true],
+      ["dom.serviceWorkers.testing.enabled", true],
+    ],
+  });
+
+  const swTab = BrowserTestUtils.addTab(gBrowser, EMPTY_PAGE);
+  const browser = gBrowser.getBrowserForTab(swTab);
+  await BrowserTestUtils.browserLoaded(browser);
+  await SpecialPowers.spawn(
+    browser,
+    [{ script: SW, scope: TEST_JSON_URL }],
+    async opts => {
+      const reg = await content.navigator.serviceWorker.register(opts.script, {
+        scope: opts.scope,
+      });
+      return new content.window.Promise(resolve => {
+        const worker = reg.installing;
+        if (worker.state === "activated") {
+          resolve();
+          return;
+        }
+        worker.addEventListener("statechange", evt => {
+          if (worker.state === "activated") {
+            resolve();
+          }
+        });
+      });
+    }
+  );
+
+  const tab = await addJsonViewTab(TEST_JSON_URL);
+
+  ok(
+    tab.linkedBrowser.contentPrincipal.isNullPrincipal,
+    "Should have null principal"
+  );
+
+  is(await countRows(), 3, "There must be three rows");
+
+  const objectCellCount = await getElementCount(
+    ".jsonPanelBox .treeTable .objectCell"
+  );
+  is(objectCellCount, 1, "There must be one object cell");
+
+  const objectCellText = await getElementText(
+    ".jsonPanelBox .treeTable .objectCell"
+  );
+  is(objectCellText, "", "The summary is hidden when object is expanded");
+
+  // Clicking the value does not collapse it (so that it can be selected and copied).
+  await clickJsonNode(".jsonPanelBox .treeTable .treeValueCell");
+  is(await countRows(), 3, "There must still be three rows");
+
+  // Clicking the label collapses the auto-expanded node.
+  await clickJsonNode(".jsonPanelBox .treeTable .treeLabel");
+  is(await countRows(), 1, "There must be one row");
+
+  await SpecialPowers.spawn(
+    browser,
+    [{ script: SW, scope: TEST_JSON_URL }],
+    async opts => {
+      const reg = await content.navigator.serviceWorker.getRegistration(
+        opts.scope
+      );
+      await reg.unregister();
+    }
+  );
+
+  BrowserTestUtils.removeTab(swTab);
+});
+
+function countRows() {
+  return getElementCount(".jsonPanelBox .treeTable .treeRow");
+}
diff --git a/devtools/client/jsonview/test/browser_jsonview_slash.js b/devtools/client/jsonview/test/browser_jsonview_slash.js
new file mode 100644
index 0000000000..f8abeca7be
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_slash.js
@@ -0,0 +1,16 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+add_task(async function () {
+  info("Test JSON with slash started.");
+
+  const TEST_JSON_URL = 'data:application/json,{"a/b":[1,2],"a":{"b":[3,4]}}';
+  await addJsonViewTab(TEST_JSON_URL);
+
+  const countBefore = await getElementCount(
+    ".jsonPanelBox .treeTable .treeRow"
+  );
+  is(countBefore, 7, "There must be seven rows");
+});
diff --git a/devtools/client/jsonview/test/browser_jsonview_theme.js b/devtools/client/jsonview/test/browser_jsonview_theme.js
new file mode 100644
index 0000000000..c66d197256
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_theme.js
@@ -0,0 +1,29 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const TEST_JSON_URL = URL_ROOT + "valid_json.json";
+
+add_task(async function () {
+  info("Test JSON theme started.");
+
+  const oldPref = Services.prefs.getCharPref("devtools.theme");
+  Services.prefs.setCharPref("devtools.theme", "light");
+
+  await addJsonViewTab(TEST_JSON_URL);
+
+  is(await getTheme(), "theme-light", "The initial theme is light");
+
+  Services.prefs.setCharPref("devtools.theme", "dark");
+  is(await getTheme(), "theme-dark", "Theme changed to dark");
+
+  Services.prefs.setCharPref("devtools.theme", "light");
+  is(await getTheme(), "theme-light", "Theme changed to light");
+
+  Services.prefs.setCharPref("devtools.theme", oldPref);
+});
+
+function getTheme() {
+  return getElementAttr(":root", "class");
+}
diff --git a/devtools/client/jsonview/test/browser_jsonview_url_linkification.js b/devtools/client/jsonview/test/browser_jsonview_url_linkification.js
new file mode 100644
index 0000000000..19d1f27f0c
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_url_linkification.js
@@ -0,0 +1,88 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const { ELLIPSIS } = require("resource://devtools/shared/l10n.js");
+
+add_task(async function () {
+  info("Test short URL linkification JSON started");
+
+  const url = "https://example.com/";
+  const tab = await addJsonViewTab(
+    "data:application/json," + JSON.stringify([url])
+  );
+  await testLinkNavigation({ browser: tab.linkedBrowser, url });
+
+  info("Switch back to the JSONViewer");
+  await BrowserTestUtils.switchTab(gBrowser, tab);
+
+  await testLinkNavigation({
+    browser: tab.linkedBrowser,
+    url,
+    clickLabel: true,
+  });
+});
+
+add_task(async function () {
+  info("Test long URL linkification JSON started");
+
+  const url = "https://example.com/" + "a".repeat(100);
+  const tab = await addJsonViewTab(
+    "data:application/json," + JSON.stringify([url])
+  );
+
+  await testLinkNavigation({ browser: tab.linkedBrowser, url });
+
+  info("Switch back to the JSONViewer");
+  await BrowserTestUtils.switchTab(gBrowser, tab);
+
+  await testLinkNavigation({
+    browser: tab.linkedBrowser,
+    url,
+    urlText: url.slice(0, 24) + ELLIPSIS + url.slice(-24),
+    clickLabel: true,
+  });
+});
+
+/**
+ * Assert that the expected link is displayed and that clicking on it navigates to the
+ * expected url.
+ *
+ * @param {Object} option object containing:
+ *        - browser (mandatory): the browser the tab will be opened in.
+ *        - url (mandatory): The url we should navigate to.
+ *        - urlText: The expected displayed text of the url.
+ *                   Falls back to `url` if not filled
+ *        - clickLabel: Should we click the label before doing assertions.
+ */
+async function testLinkNavigation({
+  browser,
+  url,
+  urlText,
+  clickLabel = false,
+}) {
+  const onTabLoaded = BrowserTestUtils.waitForNewTab(gBrowser, url);
+
+  SpecialPowers.spawn(browser, [[urlText || url, url, clickLabel]], args => {
+    const [expectedURLText, expectedURL, shouldClickLabel] = args;
+    const { document } = content;
+
+    if (shouldClickLabel === true) {
+      document.querySelector(".jsonPanelBox .treeTable .treeLabel").click();
+    }
+
+    const link = document.querySelector(
+      ".jsonPanelBox .treeTable .treeValueCell a"
+    );
+    is(link.textContent, expectedURLText, "The expected URL is displayed.");
+    is(link.href, expectedURL, "The URL was linkified.");
+
+    link.click();
+  });
+
+  const newTab = await onTabLoaded;
+  // We only need to check that newTab is truthy since
+  // BrowserTestUtils.waitForNewTab checks the URL.
+  ok(newTab, "The expected tab was opened.");
+}
diff --git a/devtools/client/jsonview/test/browser_jsonview_valid_json.js b/devtools/client/jsonview/test/browser_jsonview_valid_json.js
new file mode 100644
index 0000000000..8ffd1dc1d5
--- /dev/null
+++ b/devtools/client/jsonview/test/browser_jsonview_valid_json.js
@@ -0,0 +1,46 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const TEST_JSON_URL = URL_ROOT + "valid_json.json";
+
+add_task(async function () {
+  info("Test valid JSON started");
+
+  const tab = await addJsonViewTab(TEST_JSON_URL);
+
+  ok(
+    tab.linkedBrowser.contentPrincipal.isNullPrincipal,
+    "Should have null principal"
+  );
+
+  is(await countRows(), 3, "There must be three rows");
+
+  const objectCellCount = await getElementCount(
+    ".jsonPanelBox .treeTable .objectCell"
+  );
+  is(objectCellCount, 1, "There must be one object cell");
+
+  const objectCellText = await getElementText(
+    ".jsonPanelBox .treeTable .objectCell"
+  );
+  is(objectCellText, "", "The summary is hidden when object is expanded");
+
+  // Clicking the value does not collapse it (so that it can be selected and copied).
+  await clickJsonNode(".jsonPanelBox .treeTable .treeValueCell");
+  is(await countRows(), 3, "There must still be three rows");
+
+  // Clicking the label collapses the auto-expanded node.
+  await clickJsonNode(".jsonPanelBox .treeTable .treeLabel");
+  is(await countRows(), 1, "There must be one row");
+
+  // Collapsed nodes are preserved when switching panels.
+  await selectJsonViewContentTab("headers");
+  await selectJsonViewContentTab("json");
+  is(await countRows(), 1, "There must still be one row");
+});
+
+function countRows() {
+  return getElementCount(".jsonPanelBox .treeTable .treeRow");
+}
diff --git a/devtools/client/jsonview/test/chunked_json.sjs b/devtools/client/jsonview/test/chunked_json.sjs
new file mode 100644
index 0000000000..554b62bafd
--- /dev/null
+++ b/devtools/client/jsonview/test/chunked_json.sjs
@@ -0,0 +1,39 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+"use strict";
+
+const key = "json-viewer-chunked-response";
+function setResponse(response) {
+  setObjectState(key, response);
+}
+function getResponse() {
+  let response;
+  getObjectState(key, v => {
+    response = v;
+  });
+  return response;
+}
+
+function handleRequest(request, response) {
+  const { queryString } = request;
+  if (!queryString) {
+    response.processAsync();
+    setResponse(response);
+    response.setHeader("Content-Type", "application/json");
+    // Write something so that the JSON viewer app starts loading.
+    response.write(" ");
+    return;
+  }
+  const [command, value] = queryString.split("=");
+  switch (command) {
+    case "write":
+      getResponse().write(value);
+      break;
+    case "close":
+      getResponse().finish();
+      setResponse(null);
+      break;
+  }
+  response.setHeader("Content-Type", "text/plain");
+  response.write("ok");
+}
diff --git a/devtools/client/jsonview/test/csp_json.json b/devtools/client/jsonview/test/csp_json.json
new file mode 100644
index 0000000000..9fc9368255
--- /dev/null
+++ b/devtools/client/jsonview/test/csp_json.json
@@ -0,0 +1 @@
+{ "csp": true }
diff --git a/devtools/client/jsonview/test/csp_json.json^headers^ b/devtools/client/jsonview/test/csp_json.json^headers^
new file mode 100644
index 0000000000..d6d0a72a4b
--- /dev/null
+++ b/devtools/client/jsonview/test/csp_json.json^headers^
@@ -0,0 +1,2 @@
+Content-Type: application/json
+Content-Security-Policy: default-src 'none'; base-uri 'none';
diff --git a/devtools/client/jsonview/test/empty.html b/devtools/client/jsonview/test/empty.html
new file mode 100644
index 0000000000..c50eddd41f
--- /dev/null
+++ b/devtools/client/jsonview/test/empty.html
@@ -0,0 +1 @@
+<!doctype html>
diff --git a/devtools/client/jsonview/test/head.js b/devtools/client/jsonview/test/head.js
new file mode 100644
index 0000000000..5c9ee85ea2
--- /dev/null
+++ b/devtools/client/jsonview/test/head.js
@@ -0,0 +1,278 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+/* eslint no-unused-vars: [2, {"vars": "local", "args": "none"}] */
+
+"use strict";
+
+// shared-head.js handles imports, constants, and utility functions
+Services.scriptloader.loadSubScript(
+  "chrome://mochitests/content/browser/devtools/client/framework/test/head.js",
+  this
+);
+
+const JSON_VIEW_PREF = "devtools.jsonview.enabled";
+
+// Enable JSON View for the test
+Services.prefs.setBoolPref(JSON_VIEW_PREF, true);
+
+registerCleanupFunction(() => {
+  Services.prefs.clearUserPref(JSON_VIEW_PREF);
+});
+
+// XXX move some API into devtools/shared/test/shared-head.js
+
+/**
+ * Add a new test tab in the browser and load the given url.
+ * @param {String} url
+ *   The url to be loaded in the new tab.
+ *
+ * @param {Object} [optional]
+ *   An object with the following optional properties:
+ *   - appReadyState: The readyState of the JSON Viewer app that you want to
+ *     wait for. Its value can be one of:
+ *      - "uninitialized": The converter has started the request.
+ *        If JavaScript is disabled, there will be no more readyState changes.
+ *      - "loading": RequireJS started loading the scripts for the JSON Viewer.
+ *        If the load timeouts, there will be no more readyState changes.
+ *      - "interactive": The JSON Viewer app loaded, but possibly not all the JSON
+ *        data has been received.
+ *      - "complete" (default): The app is fully loaded with all the JSON.
+ *   - docReadyState: The standard readyState of the document that you want to
+ *     wait for. Its value can be one of:
+ *      - "loading": The JSON data has not been completely loaded (but the app might).
+ *      - "interactive": All the JSON data has been received.
+ *      - "complete" (default): Since there aren't sub-resources like images,
+ *        behaves as "interactive". Note the app might not be loaded yet.
+ */
+async function addJsonViewTab(
+  url,
+  { appReadyState = "complete", docReadyState = "complete" } = {}
+) {
+  info("Adding a new JSON tab with URL: '" + url + "'");
+  const tabAdded = BrowserTestUtils.waitForNewTab(gBrowser, url);
+  const tabLoaded = addTab(url);
+
+  // The `tabAdded` promise resolves when the JSON Viewer starts loading.
+  // This is usually what we want, however, it never resolves for unrecognized
+  // content types that trigger a download.
+  // On the other hand, `tabLoaded` always resolves, but not until the document
+  // is fully loaded, which is too late if `docReadyState !== "complete"`.
+  // Therefore, we race both promises.
+  const tab = await Promise.race([tabAdded, tabLoaded]);
+  const browser = tab.linkedBrowser;
+
+  const rootDir = getRootDirectory(gTestPath);
+
+  // Catch RequireJS errors (usually timeouts)
+  const error = tabLoaded.then(() =>
+    SpecialPowers.spawn(browser, [], function () {
+      return new Promise((resolve, reject) => {
+        const { requirejs } = content.wrappedJSObject;
+        if (requirejs) {
+          requirejs.onError = err => {
+            info(err);
+            ok(false, "RequireJS error");
+            reject(err);
+          };
+        }
+      });
+    })
+  );
+
+  const data = { rootDir, appReadyState, docReadyState };
+  await Promise.race([
+    error,
+    // eslint-disable-next-line no-shadow
+    ContentTask.spawn(browser, data, async function (data) {
+      // Check if there is a JSONView object.
+      const { JSONView } = content.wrappedJSObject;
+      if (!JSONView) {
+        throw new Error("The JSON Viewer did not load.");
+      }
+
+      const docReadyStates = ["loading", "interactive", "complete"];
+      const docReadyIndex = docReadyStates.indexOf(data.docReadyState);
+      const appReadyStates = ["uninitialized", ...docReadyStates];
+      const appReadyIndex = appReadyStates.indexOf(data.appReadyState);
+      if (docReadyIndex < 0 || appReadyIndex < 0) {
+        throw new Error("Invalid app or doc readyState parameter.");
+      }
+
+      // Wait until the document readyState suffices.
+      const { document } = content;
+      while (docReadyStates.indexOf(document.readyState) < docReadyIndex) {
+        info(
+          `DocReadyState is "${document.readyState}". Await "${data.docReadyState}"`
+        );
+        await new Promise(resolve => {
+          document.addEventListener("readystatechange", resolve, {
+            once: true,
+          });
+        });
+      }
+
+      // Wait until the app readyState suffices.
+      while (appReadyStates.indexOf(JSONView.readyState) < appReadyIndex) {
+        info(
+          `AppReadyState is "${JSONView.readyState}". Await "${data.appReadyState}"`
+        );
+        await new Promise(resolve => {
+          content.addEventListener("AppReadyStateChange", resolve, {
+            once: true,
+          });
+        });
+      }
+    }),
+  ]);
+
+  return tab;
+}
+
+/**
+ * Expanding a node in the JSON tree
+ */
+function clickJsonNode(selector) {
+  info("Expanding node: '" + selector + "'");
+
+  // eslint-disable-next-line no-shadow
+  return ContentTask.spawn(gBrowser.selectedBrowser, selector, selector => {
+    content.document.querySelector(selector).click();
+  });
+}
+
+/**
+ * Select JSON View tab (in the content).
+ */
+function selectJsonViewContentTab(name) {
+  info("Selecting tab: '" + name + "'");
+
+  // eslint-disable-next-line no-shadow
+  return ContentTask.spawn(gBrowser.selectedBrowser, name, async name => {
+    const selector = ".tabs-menu .tabs-menu-item." + CSS.escape(name) + " a";
+    const element = content.document.querySelector(selector);
+    is(element.getAttribute("aria-selected"), "false", "Tab not selected yet");
+    await new Promise(resolve => {
+      content.addEventListener("TabChanged", resolve, { once: true });
+      element.click();
+    });
+    is(element.getAttribute("aria-selected"), "true", "Tab is now selected");
+  });
+}
+
+function getElementCount(selector) {
+  info("Get element count: '" + selector + "'");
+
+  return SpecialPowers.spawn(
+    gBrowser.selectedBrowser,
+    [selector],
+    selectorChild => {
+      return content.document.querySelectorAll(selectorChild).length;
+    }
+  );
+}
+
+function getElementText(selector) {
+  info("Get element text: '" + selector + "'");
+
+  return SpecialPowers.spawn(
+    gBrowser.selectedBrowser,
+    [selector],
+    selectorChild => {
+      const element = content.document.querySelector(selectorChild);
+      return element ? element.textContent : null;
+    }
+  );
+}
+
+function getElementAttr(selector, attr) {
+  info("Get attribute '" + attr + "' for element '" + selector + "'");
+
+  return SpecialPowers.spawn(
+    gBrowser.selectedBrowser,
+    [selector, attr],
+    (selectorChild, attrChild) => {
+      const element = content.document.querySelector(selectorChild);
+      return element ? element.getAttribute(attrChild) : null;
+    }
+  );
+}
+
+function focusElement(selector) {
+  info("Focus element: '" + selector + "'");
+
+  return SpecialPowers.spawn(
+    gBrowser.selectedBrowser,
+    [selector],
+    selectorChild => {
+      const element = content.document.querySelector(selectorChild);
+      if (element) {
+        element.focus();
+      }
+    }
+  );
+}
+
+/**
+ * Send the string aStr to the focused element.
+ *
+ * For now this method only works for ASCII characters and emulates the shift
+ * key state on US keyboard layout.
+ */
+function sendString(str, selector) {
+  info("Send string: '" + str + "'");
+
+  return SpecialPowers.spawn(
+    gBrowser.selectedBrowser,
+    [selector, str],
+    (selectorChild, strChild) => {
+      if (selectorChild) {
+        const element = content.document.querySelector(selectorChild);
+        if (element) {
+          element.focus();
+        }
+      }
+
+      EventUtils.sendString(strChild, content);
+    }
+  );
+}
+
+function waitForTime(delay) {
+  return new Promise(resolve => setTimeout(resolve, delay));
+}
+
+function waitForFilter() {
+  return SpecialPowers.spawn(gBrowser.selectedBrowser, [], () => {
+    return new Promise(resolve => {
+      const firstRow = content.document.querySelector(
+        ".jsonPanelBox .treeTable .treeRow"
+      );
+
+      // Check if the filter is already set.
+      if (firstRow.classList.contains("hidden")) {
+        resolve();
+        return;
+      }
+
+      // Wait till the first row has 'hidden' class set.
+      const observer = new content.MutationObserver(function (mutations) {
+        for (let i = 0; i < mutations.length; i++) {
+          const mutation = mutations[i];
+          if (mutation.attributeName == "class") {
+            if (firstRow.classList.contains("hidden")) {
+              observer.disconnect();
+              resolve();
+              break;
+            }
+          }
+        }
+      });
+
+      observer.observe(firstRow, { attributes: true });
+    });
+  });
+}
+
+function normalizeNewLines(value) {
+  return value.replace("(\r\n|\n)", "\n");
+}
diff --git a/devtools/client/jsonview/test/invalid_json.json b/devtools/client/jsonview/test/invalid_json.json
new file mode 100644
index 0000000000..004e1e2032
--- /dev/null
+++ b/devtools/client/jsonview/test/invalid_json.json
@@ -0,0 +1 @@
+{,}
diff --git a/devtools/client/jsonview/test/invalid_json.json^headers^ b/devtools/client/jsonview/test/invalid_json.json^headers^
new file mode 100644
index 0000000000..6010bfd188
--- /dev/null
+++ b/devtools/client/jsonview/test/invalid_json.json^headers^
@@ -0,0 +1 @@
+Content-Type: application/json; charset=utf-8
diff --git a/devtools/client/jsonview/test/manifest_json.json b/devtools/client/jsonview/test/manifest_json.json
new file mode 100644
index 0000000000..b178f7acf4
--- /dev/null
+++ b/devtools/client/jsonview/test/manifest_json.json
@@ -0,0 +1,49 @@
+{
+  "name": "HackerWeb",
+  "short_name": "HackerWeb",
+  "start_url": ".",
+  "display": "standalone",
+  "background_color": "#fff",
+  "description": "A simply readable Hacker News app.",
+  "icons": [
+    {
+      "src": "images/touch/homescreen48.png",
+      "sizes": "48x48",
+      "type": "image/png"
+    },
+    {
+      "src": "images/touch/homescreen72.png",
+      "sizes": "72x72",
+      "type": "image/png"
+    },
+    {
+      "src": "images/touch/homescreen96.png",
+      "sizes": "96x96",
+      "type": "image/png"
+    },
+    {
+      "src": "images/touch/homescreen144.png",
+      "sizes": "144x144",
+      "type": "image/png"
+    },
+    {
+      "src": "images/touch/homescreen168.png",
+      "sizes": "168x168",
+      "type": "image/png"
+    },
+    {
+      "src": "images/touch/homescreen192.png",
+      "sizes": "192x192",
+      "type": "image/png"
+    }
+  ],
+  "related_applications": [
+    {
+      "platform": "web"
+    },
+    {
+      "platform": "play",
+      "url": "https://play.google.com/store/apps/details?id=cheeaun.hackerweb"
+    }
+  ]
+}
diff --git a/devtools/client/jsonview/test/manifest_json.json^headers^ b/devtools/client/jsonview/test/manifest_json.json^headers^
new file mode 100644
index 0000000000..2bab061d43
--- /dev/null
+++ b/devtools/client/jsonview/test/manifest_json.json^headers^
@@ -0,0 +1 @@
+Content-Type: application/manifest+json; charset=utf-8
diff --git a/devtools/client/jsonview/test/passthrough-sw.js b/devtools/client/jsonview/test/passthrough-sw.js
new file mode 100644
index 0000000000..019d218bc2
--- /dev/null
+++ b/devtools/client/jsonview/test/passthrough-sw.js
@@ -0,0 +1,5 @@
+"use strict";
+
+addEventListener("fetch", evt => {
+  evt.respondWith(fetch(evt.request));
+});
diff --git a/devtools/client/jsonview/test/simple_json.json b/devtools/client/jsonview/test/simple_json.json
new file mode 100644
index 0000000000..d1544242f5
--- /dev/null
+++ b/devtools/client/jsonview/test/simple_json.json
@@ -0,0 +1 @@
+{ "name": "value" }
diff --git a/devtools/client/jsonview/test/simple_json.json^headers^ b/devtools/client/jsonview/test/simple_json.json^headers^
new file mode 100644
index 0000000000..6010bfd188
--- /dev/null
+++ b/devtools/client/jsonview/test/simple_json.json^headers^
@@ -0,0 +1 @@
+Content-Type: application/json; charset=utf-8
diff --git a/devtools/client/jsonview/test/valid_json.json b/devtools/client/jsonview/test/valid_json.json
new file mode 100644
index 0000000000..ca7356ccdb
--- /dev/null
+++ b/devtools/client/jsonview/test/valid_json.json
@@ -0,0 +1,6 @@
+{
+  "family": {
+    "father": "John Doe",
+    "mother": "Alice Doe"
+  }
+}
diff --git a/devtools/client/jsonview/test/valid_json.json^headers^ b/devtools/client/jsonview/test/valid_json.json^headers^
new file mode 100644
index 0000000000..6010bfd188
--- /dev/null
+++ b/devtools/client/jsonview/test/valid_json.json^headers^
@@ -0,0 +1 @@
+Content-Type: application/json; charset=utf-8