Bug 1611360 - part 1: Make sure that test_bug1151186.html set focus to its window forcibly when the document does not receive focus event r=smaug

For testing the original symptom of bug 1151186, this test needs to set focus
to a `contenteditable` editor from `focus` event listener of the documen.
However, according to the oranges, `focus` event for the document is not fired
as expected only on Linux.  The reason is, the document sometimes does not get
focus automatically.  Therefore, this patch tries to listen `focus` event first
for keeping original path.  But if the document is not activated automatically,
sets focus to its window when next macro task runs.

Differential Revision: https://phabricator.services.mozilla.com/D62396

--HG--
extra : moz-landing-system : lando

widget/tests/chrome.ini

@@ -23,7 +23,6 @@ skip-if = toolkit != "windows"
 [test_bug593307.xhtml]
 support-files = window_bug593307_offscreen.xhtml window_bug593307_centerscreen.xhtml
 [test_bug1151186.html]
-skip-if = os == 'linux' && debug #Bug 1176038
 [test_keycodes.xhtml]
 [test_wheeltransaction.xhtml]
 support-files = window_wheeltransaction.xhtml

widget/tests/test_bug1151186.html

@@ -9,22 +9,50 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=1151186
   <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
   <link rel="stylesheet" type="text/css" href="chrome://global/skin"/>
   <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
-  <script type="application/javascript">
-
+  <script>
   /** Test for Bug 1151186 **/
   SimpleTest.waitForExplicitFinish();
 
-  document.addEventListener("focus", () => {
+  // In this test, we want to check the IME enabled state in the `contenteditable`
+  // editor which is focused by `focus` event listener of the document.
+  // However, according to the random oranges filed as bug 1176038 and bug 1611360,
+  // `focus` event are sometimes not fired on the document and the reason is,
+  // the document sometimes not focused automatically.  Therefore, this test
+  // will set focus the document when `focus` event is not fired until next
+  // macro task.
+  var focusEventFired = false;
+  function onFocus(event) {
+    is(event.target.nodeName, "#document", "focus event should be fired on the document node");
+    if (event.target != document) {
+      return;
+    }
+    focusEventFired = true;
     document.getElementById("editor").focus();
     SimpleTest.executeSoon(runTests);
-  });
+  }
+  document.addEventListener("focus", onFocus, {once: true});
+
+  // Register next macro task to check whether `focus` event of the document
+  // is fired as expected.  If not, let's focus our window manually.  Then,
+  // the `focus` event listener starts the test anyway.
+  setTimeout(() => {
+   if (focusEventFired) {
+     return; // We've gotten `focus` event as expected.
+   }
+   ok(!document.hasFocus(), "The document should not have focus yet");
+   info("Setting focus to the window forcibly...");
+   window.focus();
+  }, 0);
 
   function runTests() {
+    let description = focusEventFired ?
+        "document got focused normally" :
+        "document got focused forcibly";
     is(document.activeElement, document.getElementById("editor"),
-       "The div element should be focused");
+       `The div element should be focused (${description})`);
     var utils = SpecialPowers.getDOMWindowUtils(window);
     is(utils.IMEStatus, utils.IME_STATUS_ENABLED,
-       "IME should be enabled");
+       `IME should be enabled (${description})`);
     SimpleTest.finish();
   }
   </script>