Bug 1590111 - Make the test 'test_bug346659.html' compatible with fission. r=bzbarsky

This patch makes several changes in order to enable it in Fission.

1. We modify the way how testing child window and iframe get the test
number. It used to get the test number through opener/parent. However,
the property of the opener/parent is inaccessible if it is cross site.
So, for load tests, we use url parameter to propagate the test number to
child window. For write tests, we directly write the test number in the
markup.

2. We change to use SpecialPowers.spawn() to access testing window since
they could be cross origin from the test script.

In addition, we add comments for better understanding the test script
itself.

Differential Revision: https://phabricator.services.mozilla.com/D51005

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

dom/tests/mochitest/bugs/bug346659-opener-echoer.html

@@ -1,6 +1,6 @@
 <script>
-  var win = SpecialPowers.wrap(window).wrappedJSObject;
-  win.opener.opener.postMessage(win.opener.testNum + " - " + win.x, "http://mochi.test:8888");
-  win.opener.close();
-  win.close();
+  var testNum = decodeURIComponent(window.location.search.substring(1));
+  window.opener.opener.postMessage(testNum + " - " + window.x, "http://mochi.test:8888");
+  window.opener.close();
+  window.close();
 </script>

dom/tests/mochitest/bugs/bug346659-opener.html

@@ -2,12 +2,6 @@
   <script>
     function postBack() {
       var s = decodeURIComponent(window.location.search.substring(1));
-      var cmd = JSON.parse(s);
-      if ("load" in cmd) {
-        window.testNum = cmd.load;
-      } else if ("write" in cmd) {
-        window.testNum = cmd.write;
-      }
       window.opener.postMessage(s, "http://mochi.test:8888");
     }
     var childWin = window.open();

dom/tests/mochitest/bugs/bug346659-parent-echoer.html

@@ -1,5 +1,5 @@
 <script>
-  var win = SpecialPowers.wrap(window).wrappedJSObject;
-  win.parent.opener.postMessage(win.parent.testNum + " - " + win.x, "http://mochi.test:8888");
-  win.parent.close();
+  var testNum = decodeURIComponent(window.location.search.substring(1));
+  window.parent.opener.postMessage(testNum + " - " + window.x, "http://mochi.test:8888");
+  window.parent.close();
 </script>

dom/tests/mochitest/bugs/bug346659-parent.html

@@ -4,12 +4,6 @@
     function postBack() {
       childWin = window.frames[0];
       var s = decodeURIComponent(window.location.search.substring(1));
-      var cmd = JSON.parse(s);
-      if ("load" in cmd) {
-        window.testNum = cmd.load;
-      } else if ("write" in cmd) {
-        window.testNum = cmd.write;
-      }
       window.opener.postMessage(s, "http://mochi.test:8888");
     }
   </script>

dom/tests/mochitest/bugs/mochitest.ini

@@ -59,7 +59,7 @@ skip-if = fission
 [test_bug342448.html]
 [test_bug345521.html]
 [test_bug346659.html]
-skip-if = fission || (toolkit == 'android' && !is_fennec && debug)
+skip-if = toolkit == 'android' && !is_fennec && debug
 [test_bug369306.html]
 [test_bug370098.html]
 [test_bug377539.html]

dom/tests/mochitest/bugs/test_bug346659.html

@@ -28,53 +28,94 @@ function r(base, tail) {
   return base.replace(/\/[^\/]*$/, "/" + tail);
 }
 
-function handleCmd(evt) {
+/**
+ * This function sets up the test according to the data it receives. If the data
+ * is a JSON string, it will use the object parsed from that to determine how to
+ * set up the test.
+ */
+async function handleCmd(evt) {
   var cmd;
   try {
     cmd = JSON.parse(evt.data);
   } catch (e) {
-    // Not json
+    // Not json, so it should be a test result. We don't need to set up test.
     return false;
   }  
 
   if ("load" in cmd) {
     var testNum = cmd.load;
-    var win = SpecialPowers.wrap(wins[testNum]).wrappedJSObject;
-    win.childWin.x = testNum;
-    if (SpecialPowers.unwrap(win.childWin.opener) == SpecialPowers.unwrap(win)) {
+
+    // Set up the testing window property and get necessary information from it.
+    // We use SpecialPowers.spawn() here since the testing window could be cross
+    // origin.
+    var { isOpenerTest, location } =
+      await SpecialPowers.spawn(wins[testNum], [testNum], testNum => {
+        var win = content.wrappedJSObject;
+        win.childWin.x = testNum;
+
+        return {
+          isOpenerTest: win.childWin.opener == win,
+          location: content.location.href,
+        };
+      });
+
+    // Get the test location according to the test.
+    if (isOpenerTest) {
       if ("xsite" in cmd) {
-        var loc = r(window.location.href, "bug346659-opener-echoer.html");
+        var loc = r(window.location.href, "bug346659-opener-echoer.html?" + testNum);
       } else {
-        var loc = r(win.location.href, "bug346659-opener-echoer.html");
+        var loc = r(location, "bug346659-opener-echoer.html?" + testNum);
       }
     } else {
       if ("xsite" in cmd) {
-        var loc = r(window.location.href, "bug346659-parent-echoer.html");
+        var loc = r(window.location.href, "bug346659-parent-echoer.html?" + testNum);
       } else {
-        var loc = r(win.location.href, "bug346659-parent-echoer.html");
+        var loc = r(location, "bug346659-parent-echoer.html?" + testNum);
       }
     }
-    win.childWin.location.href = loc;
+
+    // Trigger the loading on the child window of the testing window.
+    await SpecialPowers.spawn(wins[testNum], [loc], loc => {
+      content.wrappedJSObject.childWin.location.href = loc;
+    });
     wins[testNum] = null;
   } else if ("write" in cmd) {
     var testNum = cmd.write;
-    var win = wins[testNum];
-    win.childWin.x = testNum;
+
     try {
-      if (win.childWin.opener == win) {
-        win.childWin.document.write('<script>window.opener.opener.postMessage(window.opener.testNum + " - " + window.x, "http://mochi.test:8888/"); window.opener.close(); window.close();<' + '/script>');
-      } else {
-        win.childWin.document.write('<script>window.parent.opener.postMessage(window.parent.testNum + " - " + window.x, "http://mochi.test:8888/"); window.parent.close();<' + '/script>');
-      }
+      // Set up the test on the testing window.
+      await SpecialPowers.spawn(wins[testNum], [testNum], testNum => {
+        var win = content.wrappedJSObject;
+        win.childWin.x = testNum;
+
+        // Test document.write().
+        if (win.childWin.opener == win) {
+          win.childWin.document.write(`
+            <script>
+              window.opener.opener.postMessage("${testNum} - " + window.x, "http://mochi.test:8888/");
+              window.opener.close();
+              window.close();
+            <` + '/script>');
+        } else {
+          win.childWin.document.write(`
+            <script>
+              window.parent.opener.postMessage("${testNum} - " + window.x, "http://mochi.test:8888/");
+              window.parent.close();
+            <` + '/script>');
+        }
+      });
     } catch (e) {
       if (e.name != "SecurityError" || e.code != 18) {
         throw e;
       }
       // Security error on cross-site write() is fine
-      if (win.childWin.opener == win) {
-        win.childWin.close();
-      }
-      win.close()
+      await SpecialPowers.spawn(wins[testNum], [], () => {
+        var win = content.wrappedJSObject;
+        if (win.childWin.opener == win) {
+          win.childWin.close();
+        }
+      });
+
       handleTestEnd();
     }
     wins[testNum] = null;
@@ -82,9 +123,9 @@ function handleCmd(evt) {
   return true;
 }
 
-function messageReceiver(evt) {
+async function messageReceiver(evt) {
   // First try to detect a load/write command
-  if (handleCmd(evt)) {
+  if (await handleCmd(evt)) {
     return;
   }