Adding upstream version 115.7.0esr.upstream/115.7.0esr

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

9 files changed, 693 insertions, 0 deletions

diff --git a/accessible/tests/browser/fission/browser.ini b/accessible/tests/browser/fission/browser.ini
new file mode 100644
index 0000000000..c898fb54d2
--- /dev/null
+++ b/accessible/tests/browser/fission/browser.ini
@@ -0,0 +1,20 @@
+[DEFAULT]
+subsuite = a11y
+support-files =
+  head.js
+  !/accessible/tests/browser/shared-head.js
+  !/accessible/tests/browser/*.jsm
+  !/accessible/tests/mochitest/*.js
+prefs =
+  javascript.options.asyncstack_capture_debuggee_only=false
+
+[browser_content_tree.js]
+[browser_hidden_iframe.js]
+https_first_disabled = true
+[browser_nested_iframe.js]
+skip-if =
+  os == "win" && os_version == "6.1" # Skip on Azure - frequent failure
+[browser_reframe_root.js]
+[browser_reframe_visibility.js]
+[browser_src_change.js]
+[browser_take_focus.js]
diff --git a/accessible/tests/browser/fission/browser_content_tree.js b/accessible/tests/browser/fission/browser_content_tree.js
new file mode 100644
index 0000000000..1592ae6a1a
--- /dev/null
+++ b/accessible/tests/browser/fission/browser_content_tree.js
@@ -0,0 +1,75 @@
+/* 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";
+
+/* import-globals-from ../../mochitest/role.js */
+loadScripts({ name: "role.js", dir: MOCHITESTS_DIR });
+
+addAccessibleTask(
+  `<table id="table">
+    <tr>
+      <td>cell1</td>
+      <td>cell2</td>
+    </tr>
+  </table>
+  <ul id="ul">
+    <li id="li">item1</li>
+  </ul>`,
+  async function (browser, iframeDocAcc, contentDocAcc) {
+    ok(iframeDocAcc, "IFRAME document accessible is present");
+    (gIsRemoteIframe ? isnot : is)(
+      browser.browsingContext.currentWindowGlobal.osPid,
+      browser.browsingContext.children[0].currentWindowGlobal.osPid,
+      `Content and IFRAME documents are in ${
+        gIsRemoteIframe ? "separate processes" : "same process"
+      }.`
+    );
+
+    const tree = {
+      DOCUMENT: [
+        {
+          INTERNAL_FRAME: [
+            {
+              DOCUMENT: [
+                {
+                  TABLE: [
+                    {
+                      ROW: [
+                        { CELL: [{ TEXT_LEAF: [] }] },
+                        { CELL: [{ TEXT_LEAF: [] }] },
+                      ],
+                    },
+                  ],
+                },
+                {
+                  LIST: [
+                    {
+                      LISTITEM: [{ LISTITEM_MARKER: [] }, { TEXT_LEAF: [] }],
+                    },
+                  ],
+                },
+              ],
+            },
+          ],
+        },
+      ],
+    };
+    testAccessibleTree(contentDocAcc, tree);
+
+    const iframeAcc = contentDocAcc.getChildAt(0);
+    is(
+      iframeAcc.getChildAt(0),
+      iframeDocAcc,
+      "Document for the IFRAME matches IFRAME's first child."
+    );
+
+    is(
+      iframeDocAcc.parent,
+      iframeAcc,
+      "IFRAME document's parent matches the IFRAME."
+    );
+  },
+  { topLevel: false, iframe: true, remoteIframe: true }
+);
diff --git a/accessible/tests/browser/fission/browser_hidden_iframe.js b/accessible/tests/browser/fission/browser_hidden_iframe.js
new file mode 100644
index 0000000000..61414b611d
--- /dev/null
+++ b/accessible/tests/browser/fission/browser_hidden_iframe.js
@@ -0,0 +1,70 @@
+/* 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";
+
+/* import-globals-from ../../mochitest/states.js */
+/* import-globals-from ../../mochitest/role.js */
+loadScripts({ name: "states.js", dir: MOCHITESTS_DIR });
+loadScripts({ name: "role.js", dir: MOCHITESTS_DIR });
+
+addAccessibleTask(
+  `<input id="textbox" value="hello"/>`,
+  async function (browser, contentDocAcc) {
+    info(
+      "Check that the IFRAME and the IFRAME document are not accessible initially."
+    );
+    let iframeAcc = findAccessibleChildByID(contentDocAcc, DEFAULT_IFRAME_ID);
+    let iframeDocAcc = findAccessibleChildByID(
+      contentDocAcc,
+      DEFAULT_IFRAME_DOC_BODY_ID
+    );
+    ok(!iframeAcc, "IFRAME is hidden and should not be accessible");
+    ok(!iframeDocAcc, "IFRAME document is hidden and should not be accessible");
+
+    info(
+      "Show the IFRAME and check that it's now available in the accessibility tree."
+    );
+
+    const events = [[EVENT_REORDER, contentDocAcc]];
+
+    const onEvents = waitForEvents(events);
+    await SpecialPowers.spawn(browser, [DEFAULT_IFRAME_ID], contentId => {
+      content.document.getElementById(contentId).style.display = "";
+    });
+    await onEvents;
+
+    iframeAcc = findAccessibleChildByID(contentDocAcc, DEFAULT_IFRAME_ID);
+    ok(!isDefunct(iframeAcc), "IFRAME should be accessible");
+
+    // Wait for the child iframe to layout itself. This can happen during or
+    // after the reorder event, depending on timing.
+    iframeDocAcc = await TestUtils.waitForCondition(() => {
+      return findAccessibleChildByID(contentDocAcc, DEFAULT_IFRAME_DOC_BODY_ID);
+    });
+
+    is(iframeAcc.childCount, 1, "IFRAME accessible should have a single child");
+    ok(iframeDocAcc, "IFRAME document exists");
+    ok(!isDefunct(iframeDocAcc), "IFRAME document should be accessible");
+    is(
+      iframeAcc.firstChild,
+      iframeDocAcc,
+      "An accessible for a IFRAME document is the child of the IFRAME accessible"
+    );
+    is(
+      iframeDocAcc.parent,
+      iframeAcc,
+      "IFRAME document's parent matches the IFRAME."
+    );
+  },
+  {
+    topLevel: false,
+    iframe: true,
+    remoteIframe: true,
+    iframeAttrs: {
+      style: "display: none;",
+    },
+    skipFissionDocLoad: true,
+  }
+);
diff --git a/accessible/tests/browser/fission/browser_nested_iframe.js b/accessible/tests/browser/fission/browser_nested_iframe.js
new file mode 100644
index 0000000000..d6600a2d5e
--- /dev/null
+++ b/accessible/tests/browser/fission/browser_nested_iframe.js
@@ -0,0 +1,164 @@
+/* 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";
+
+/* import-globals-from ../../mochitest/role.js */
+loadScripts({ name: "role.js", dir: MOCHITESTS_DIR });
+
+const NESTED_IFRAME_DOC_BODY_ID = "nested-iframe-body";
+const NESTED_IFRAME_ID = "nested-iframe";
+// eslint-disable-next-line @microsoft/sdl/no-insecure-url
+const nestedURL = new URL(`http://example.com/document-builder.sjs`);
+nestedURL.searchParams.append(
+  "html",
+  `<html>
+      <head>
+        <meta charset="utf-8"/>
+        <title>Accessibility Nested Iframe Frame Test</title>
+      </head>
+      <body id="${NESTED_IFRAME_DOC_BODY_ID}">
+        <table id="table">
+          <tr>
+            <td>cell1</td>
+            <td>cell2</td>
+          </tr>
+        </table>
+        <ul id="ul">
+          <li id="li">item1</li>
+        </ul>
+      </body>
+    </html>`
+);
+
+function getOsPid(browsingContext) {
+  return browsingContext.currentWindowGlobal.osPid;
+}
+
+addAccessibleTask(
+  `<iframe id="${NESTED_IFRAME_ID}" src="${nestedURL.href}"/>`,
+  async function (browser, iframeDocAcc, contentDocAcc) {
+    ok(iframeDocAcc, "IFRAME document accessible is present");
+    let nestedDocAcc = findAccessibleChildByID(
+      iframeDocAcc,
+      NESTED_IFRAME_DOC_BODY_ID
+    );
+    let waitForNestedDocLoad = false;
+    if (nestedDocAcc) {
+      const state = {};
+      nestedDocAcc.getState(state, {});
+      if (state.value & STATE_BUSY) {
+        info("Nested IFRAME document accessible is present but busy");
+        waitForNestedDocLoad = true;
+      } else {
+        ok(true, "Nested IFRAME document accessible is present and ready");
+      }
+    } else {
+      info("Nested IFRAME document accessible is not present yet");
+      waitForNestedDocLoad = true;
+    }
+    if (waitForNestedDocLoad) {
+      info("Waiting for doc load complete on nested iframe document");
+      nestedDocAcc = (
+        await waitForEvent(
+          EVENT_DOCUMENT_LOAD_COMPLETE,
+          NESTED_IFRAME_DOC_BODY_ID
+        )
+      ).accessible;
+    }
+
+    if (gIsRemoteIframe) {
+      isnot(
+        getOsPid(browser.browsingContext),
+        getOsPid(browser.browsingContext.children[0]),
+        `Content and IFRAME documents are in separate processes.`
+      );
+      isnot(
+        getOsPid(browser.browsingContext),
+        getOsPid(browser.browsingContext.children[0].children[0]),
+        `Content and nested IFRAME documents are in separate processes.`
+      );
+      isnot(
+        getOsPid(browser.browsingContext.children[0]),
+        getOsPid(browser.browsingContext.children[0].children[0]),
+        `IFRAME and nested IFRAME documents are in separate processes.`
+      );
+    } else {
+      is(
+        getOsPid(browser.browsingContext),
+        getOsPid(browser.browsingContext.children[0]),
+        `Content and IFRAME documents are in same processes.`
+      );
+      if (gFissionBrowser) {
+        isnot(
+          getOsPid(browser.browsingContext.children[0]),
+          getOsPid(browser.browsingContext.children[0].children[0]),
+          `IFRAME and nested IFRAME documents are in separate processes.`
+        );
+      } else {
+        is(
+          getOsPid(browser.browsingContext),
+          getOsPid(browser.browsingContext.children[0].children[0]),
+          `Content and nested IFRAME documents are in same processes.`
+        );
+      }
+    }
+
+    const tree = {
+      DOCUMENT: [
+        {
+          INTERNAL_FRAME: [
+            {
+              DOCUMENT: [
+                {
+                  INTERNAL_FRAME: [
+                    {
+                      DOCUMENT: [
+                        {
+                          TABLE: [
+                            {
+                              ROW: [
+                                { CELL: [{ TEXT_LEAF: [] }] },
+                                { CELL: [{ TEXT_LEAF: [] }] },
+                              ],
+                            },
+                          ],
+                        },
+                        {
+                          LIST: [
+                            {
+                              LISTITEM: [
+                                { LISTITEM_MARKER: [] },
+                                { TEXT_LEAF: [] },
+                              ],
+                            },
+                          ],
+                        },
+                      ],
+                    },
+                  ],
+                },
+              ],
+            },
+          ],
+        },
+      ],
+    };
+    testAccessibleTree(contentDocAcc, tree);
+
+    const nestedIframeAcc = iframeDocAcc.getChildAt(0);
+    is(
+      nestedIframeAcc.getChildAt(0),
+      nestedDocAcc,
+      "Document for nested IFRAME matches."
+    );
+
+    is(
+      nestedDocAcc.parent,
+      nestedIframeAcc,
+      "Nested IFRAME document's parent matches the nested IFRAME."
+    );
+  },
+  { topLevel: false, iframe: true, remoteIframe: true }
+);
diff --git a/accessible/tests/browser/fission/browser_reframe_root.js b/accessible/tests/browser/fission/browser_reframe_root.js
new file mode 100644
index 0000000000..d7123109f4
--- /dev/null
+++ b/accessible/tests/browser/fission/browser_reframe_root.js
@@ -0,0 +1,95 @@
+/* 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";
+
+/* import-globals-from ../../mochitest/states.js */
+/* import-globals-from ../../mochitest/role.js */
+loadScripts(
+  { name: "role.js", dir: MOCHITESTS_DIR },
+  { name: "states.js", dir: MOCHITESTS_DIR }
+);
+
+addAccessibleTask(
+  `<input id="textbox" value="hello"/>`,
+  async function (browser, iframeDocAcc, contentDocAcc) {
+    info(
+      "Check that the IFRAME and the IFRAME document are accessible initially."
+    );
+    let iframeAcc = findAccessibleChildByID(contentDocAcc, DEFAULT_IFRAME_ID);
+    ok(!isDefunct(iframeAcc), "IFRAME should be accessible");
+    ok(!isDefunct(iframeDocAcc), "IFRAME document should be accessible");
+
+    info("Move the IFRAME under a new hidden root.");
+    let onEvents = waitForEvent(EVENT_REORDER, contentDocAcc);
+    await SpecialPowers.spawn(browser, [DEFAULT_IFRAME_ID], id => {
+      const doc = content.document;
+      const root = doc.createElement("div");
+      root.style.display = "none";
+      doc.body.appendChild(root);
+      root.appendChild(doc.getElementById(id));
+    });
+    await onEvents;
+
+    ok(
+      isDefunct(iframeAcc),
+      "IFRAME accessible should be defunct when hidden."
+    );
+    ok(
+      isDefunct(iframeDocAcc),
+      "IFRAME document's accessible should be defunct when the IFRAME is hidden."
+    );
+    ok(
+      !findAccessibleChildByID(contentDocAcc, DEFAULT_IFRAME_ID),
+      "No accessible for an IFRAME present."
+    );
+    ok(
+      !findAccessibleChildByID(contentDocAcc, DEFAULT_IFRAME_DOC_BODY_ID),
+      "No accessible for the IFRAME document present."
+    );
+
+    info("Move the IFRAME back under the content document's body.");
+    onEvents = waitForEvents([
+      [EVENT_REORDER, contentDocAcc],
+      [
+        EVENT_STATE_CHANGE,
+        event => {
+          const scEvent = event.QueryInterface(nsIAccessibleStateChangeEvent);
+          const id = getAccessibleDOMNodeID(event.accessible);
+          return (
+            id === DEFAULT_IFRAME_DOC_BODY_ID &&
+            scEvent.state === STATE_BUSY &&
+            scEvent.isEnabled === false
+          );
+        },
+      ],
+    ]);
+    await SpecialPowers.spawn(browser, [DEFAULT_IFRAME_ID], id => {
+      content.document.body.appendChild(content.document.getElementById(id));
+    });
+    await onEvents;
+
+    iframeAcc = findAccessibleChildByID(contentDocAcc, DEFAULT_IFRAME_ID);
+    const newiframeDocAcc = iframeAcc.firstChild;
+
+    ok(!isDefunct(iframeAcc), "IFRAME should be accessible");
+    is(iframeAcc.childCount, 1, "IFRAME accessible should have a single child");
+    ok(!isDefunct(newiframeDocAcc), "IFRAME document should be accessible");
+    ok(
+      isDefunct(iframeDocAcc),
+      "Original IFRAME document accessible should be defunct."
+    );
+    isnot(
+      iframeAcc.firstChild,
+      iframeDocAcc,
+      "A new accessible is created for a IFRAME document."
+    );
+    is(
+      iframeAcc.firstChild,
+      newiframeDocAcc,
+      "A new accessible for a IFRAME document is the child of the IFRAME accessible"
+    );
+  },
+  { topLevel: false, iframe: true, remoteIframe: true }
+);
diff --git a/accessible/tests/browser/fission/browser_reframe_visibility.js b/accessible/tests/browser/fission/browser_reframe_visibility.js
new file mode 100644
index 0000000000..8aee02037c
--- /dev/null
+++ b/accessible/tests/browser/fission/browser_reframe_visibility.js
@@ -0,0 +1,116 @@
+/* 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";
+
+/* import-globals-from ../../mochitest/states.js */
+/* import-globals-from ../../mochitest/role.js */
+loadScripts({ name: "states.js", dir: MOCHITESTS_DIR });
+loadScripts({ name: "role.js", dir: MOCHITESTS_DIR });
+
+addAccessibleTask(
+  `<input id="textbox" value="hello"/>`,
+  async function (browser, iframeDocAcc, contentDocAcc) {
+    info(
+      "Check that the IFRAME and the IFRAME document are accessible initially."
+    );
+    let iframeAcc = findAccessibleChildByID(contentDocAcc, DEFAULT_IFRAME_ID);
+    ok(!isDefunct(iframeAcc), "IFRAME should be accessible");
+    ok(!isDefunct(iframeDocAcc), "IFRAME document should be accessible");
+
+    info(
+      "Hide the IFRAME and check that it's gone along with the IFRAME document."
+    );
+    let onEvents = waitForEvent(EVENT_REORDER, contentDocAcc);
+    await SpecialPowers.spawn(browser, [DEFAULT_IFRAME_ID], contentId => {
+      content.document.getElementById(contentId).style.display = "none";
+    });
+    await onEvents;
+
+    ok(
+      isDefunct(iframeAcc),
+      "IFRAME accessible should be defunct when hidden."
+    );
+    if (gIsRemoteIframe) {
+      ok(
+        !isDefunct(iframeDocAcc),
+        "IFRAME document's accessible is not defunct when the IFRAME is hidden and fission is enabled."
+      );
+    } else {
+      ok(
+        isDefunct(iframeDocAcc),
+        "IFRAME document's accessible is defunct when the IFRAME is hidden and fission is not enabled."
+      );
+    }
+    ok(
+      !findAccessibleChildByID(contentDocAcc, DEFAULT_IFRAME_ID),
+      "No accessible for an IFRAME present."
+    );
+    ok(
+      !findAccessibleChildByID(contentDocAcc, DEFAULT_IFRAME_DOC_BODY_ID),
+      "No accessible for the IFRAME document present."
+    );
+
+    info(
+      "Show the IFRAME and check that a new accessible is created for it as " +
+        "well as the IFRAME document."
+    );
+
+    const events = [[EVENT_REORDER, contentDocAcc]];
+    if (!gIsRemoteIframe) {
+      events.push([
+        EVENT_STATE_CHANGE,
+        event => {
+          const scEvent = event.QueryInterface(nsIAccessibleStateChangeEvent);
+          const id = getAccessibleDOMNodeID(event.accessible);
+          return (
+            id === DEFAULT_IFRAME_DOC_BODY_ID &&
+            scEvent.state === STATE_BUSY &&
+            scEvent.isEnabled === false
+          );
+        },
+      ]);
+    }
+    onEvents = waitForEvents(events);
+    await SpecialPowers.spawn(browser, [DEFAULT_IFRAME_ID], contentId => {
+      content.document.getElementById(contentId).style.display = "block";
+    });
+    await onEvents;
+
+    iframeAcc = findAccessibleChildByID(contentDocAcc, DEFAULT_IFRAME_ID);
+    const newiframeDocAcc = iframeAcc.firstChild;
+
+    ok(!isDefunct(iframeAcc), "IFRAME should be accessible");
+    is(iframeAcc.childCount, 1, "IFRAME accessible should have a single child");
+    ok(newiframeDocAcc, "IFRAME document exists");
+    ok(!isDefunct(newiframeDocAcc), "IFRAME document should be accessible");
+    if (gIsRemoteIframe) {
+      ok(
+        !isDefunct(iframeDocAcc),
+        "Original IFRAME document accessible should not be defunct when fission is enabled."
+      );
+      is(
+        iframeAcc.firstChild,
+        iframeDocAcc,
+        "Existing accessible is used for a IFRAME document."
+      );
+    } else {
+      ok(
+        isDefunct(iframeDocAcc),
+        "Original IFRAME document accessible should be defunct when fission is not enabled."
+      );
+      isnot(
+        iframeAcc.firstChild,
+        iframeDocAcc,
+        "A new accessible is created for a IFRAME document."
+      );
+    }
+    is(
+      iframeAcc.firstChild,
+      newiframeDocAcc,
+      "A new accessible for a IFRAME document is the child of the IFRAME accessible"
+    );
+  },
+  { topLevel: false, iframe: true, remoteIframe: true }
+);
diff --git a/accessible/tests/browser/fission/browser_src_change.js b/accessible/tests/browser/fission/browser_src_change.js
new file mode 100644
index 0000000000..e97cda3cc3
--- /dev/null
+++ b/accessible/tests/browser/fission/browser_src_change.js
@@ -0,0 +1,62 @@
+/* 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";
+
+/* import-globals-from ../../mochitest/role.js */
+loadScripts({ name: "role.js", dir: MOCHITESTS_DIR });
+
+addAccessibleTask(
+  `<input id="textbox" value="hello"/>`,
+  async function (browser, iframeDocAcc, contentDocAcc) {
+    info(
+      "Check that the IFRAME and the IFRAME document are accessible initially."
+    );
+    let iframeAcc = findAccessibleChildByID(contentDocAcc, DEFAULT_IFRAME_ID);
+    ok(isAccessible(iframeAcc), "IFRAME should be accessible");
+    ok(isAccessible(iframeDocAcc), "IFRAME document should be accessible");
+
+    info("Replace src URL for the IFRAME with one with different origin.");
+    const onDocLoad = waitForEvent(
+      EVENT_DOCUMENT_LOAD_COMPLETE,
+      DEFAULT_IFRAME_DOC_BODY_ID
+    );
+
+    await SpecialPowers.spawn(
+      browser,
+      [DEFAULT_IFRAME_ID, CURRENT_CONTENT_DIR],
+      (id, olddir) => {
+        const { src } = content.document.getElementById(id);
+        content.document.getElementById(id).src = src.replace(
+          olddir,
+          // eslint-disable-next-line @microsoft/sdl/no-insecure-url
+          "http://example.net/browser/accessible/tests/browser/"
+        );
+      }
+    );
+    const newiframeDocAcc = (await onDocLoad).accessible;
+
+    ok(isAccessible(iframeAcc), "IFRAME should be accessible");
+    ok(
+      isAccessible(newiframeDocAcc),
+      "new IFRAME document should be accessible"
+    );
+    isnot(
+      iframeDocAcc,
+      newiframeDocAcc,
+      "A new accessible is created for a IFRAME document."
+    );
+    is(
+      iframeAcc.firstChild,
+      newiframeDocAcc,
+      "An IFRAME has a new accessible for a IFRAME document as a child."
+    );
+    is(
+      newiframeDocAcc.parent,
+      iframeAcc,
+      "A new accessible for a IFRAME document has an IFRAME as a parent."
+    );
+  },
+  { topLevel: false, iframe: true, remoteIframe: true }
+);
diff --git a/accessible/tests/browser/fission/browser_take_focus.js b/accessible/tests/browser/fission/browser_take_focus.js
new file mode 100644
index 0000000000..7ec037566d
--- /dev/null
+++ b/accessible/tests/browser/fission/browser_take_focus.js
@@ -0,0 +1,73 @@
+/* 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";
+
+/* import-globals-from ../../mochitest/states.js */
+loadScripts(
+  { name: "role.js", dir: MOCHITESTS_DIR },
+  { name: "states.js", dir: MOCHITESTS_DIR }
+);
+
+addAccessibleTask(
+  `<div role="group"><input id="textbox" value="hello"/></div>`,
+  async function (browser, iframeDocAcc, contentDocAcc) {
+    const textbox = findAccessibleChildByID(iframeDocAcc, "textbox");
+    const iframe = findAccessibleChildByID(contentDocAcc, "default-iframe-id");
+    const iframeDoc = findAccessibleChildByID(
+      contentDocAcc,
+      "default-iframe-body-id"
+    );
+    const root = getRootAccessible(document);
+
+    testStates(textbox, STATE_FOCUSABLE, 0, STATE_FOCUSED);
+
+    let onFocus = waitForEvent(EVENT_FOCUS, textbox);
+    textbox.takeFocus();
+    await onFocus;
+
+    testStates(textbox, STATE_FOCUSABLE | STATE_FOCUSED, 0);
+
+    is(
+      getAccessibleDOMNodeID(contentDocAcc.focusedChild),
+      "textbox",
+      "correct focusedChild from top doc"
+    );
+
+    is(
+      getAccessibleDOMNodeID(iframeDocAcc.focusedChild),
+      "textbox",
+      "correct focusedChild from iframe"
+    );
+
+    is(
+      getAccessibleDOMNodeID(root.focusedChild),
+      "textbox",
+      "correct focusedChild from root"
+    );
+
+    ok(!iframe.focusedChild, "correct focusedChild from iframe (null)");
+
+    onFocus = waitForEvent(EVENT_FOCUS, iframeDoc);
+    iframeDoc.takeFocus();
+    await onFocus;
+
+    is(
+      getAccessibleDOMNodeID(contentDocAcc.focusedChild),
+      "default-iframe-body-id",
+      "correct focusedChild of child doc from top doc"
+    );
+    is(
+      getAccessibleDOMNodeID(iframe.focusedChild),
+      "default-iframe-body-id",
+      "correct focusedChild of child doc from iframe"
+    );
+    is(
+      getAccessibleDOMNodeID(root.focusedChild),
+      "default-iframe-body-id",
+      "correct focusedChild of child doc from root"
+    );
+  },
+  { topLevel: false, iframe: true, remoteIframe: true }
+);
diff --git a/accessible/tests/browser/fission/head.js b/accessible/tests/browser/fission/head.js
new file mode 100644
index 0000000000..afc50984bd
--- /dev/null
+++ b/accessible/tests/browser/fission/head.js
@@ -0,0 +1,18 @@
+/* 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";
+
+// Load the shared-head file first.
+Services.scriptloader.loadSubScript(
+  "chrome://mochitests/content/browser/accessible/tests/browser/shared-head.js",
+  this
+);
+
+// Loading and common.js from accessible/tests/mochitest/ for all tests, as
+// well as promisified-events.js.
+loadScripts(
+  { name: "common.js", dir: MOCHITESTS_DIR },
+  { name: "promisified-events.js", dir: MOCHITESTS_DIR }
+);