Bug 1724026 - Support running existing Extension API mochitests with a background service worker. r=mixedpuppy

Provide a way to use service workers as the background script in existing tests, possibly by only
requiring minimal changes to the existing test cases.

This patch includes:

- changes needed to detect when a test extension is being created for a test running in
  the "background service worker mode" and automatically turn the background script into
  a background service worker (instead of a background page) when not explicitly listed
  in the test extension manifest

- a new mochitest-serviceworker.ini manifest where new or existing test files meant to be run on a
  background service worker can be added to run them automatically in the "background service worker mode"

- a new test_verify_sw_mode.html smoke test that make sure the mochitest-serviceworker.ini manifest
  is running in the expected mode.

- a new `sw-webextension` tag, which can be used locally to run a test file only in the
  "background service worker mode"

- changes to test_ext_test.html to make it able to run in both background pages and background workers

- small tweaks to `test` API (both the WebIDL binding and the current bindings injected from privileged
  js code, to better match each other behavior)

Differential Revision: https://phabricator.services.mozilla.com/D122536

testing/mochitest/tests/SimpleTest/ExtensionTestUtils.js

@@ -1,10 +1,22 @@
-var ExtensionTestUtils = {};
-
 const { ExtensionTestCommon } = SpecialPowers.Cu.import(
   "resource://testing-common/ExtensionTestCommon.jsm",
   {}
 );
 
+var ExtensionTestUtils = {
+  // Shortcut to more easily access WebExtensionPolicy.backgroundServiceWorkerEnabled
+  // from mochitest-plain tests.
+  getBackgroundServiceWorkerEnabled() {
+    return ExtensionTestCommon.getBackgroundServiceWorkerEnabled();
+  },
+
+  // A test helper used to check if the pref "extension.backgroundServiceWorker.forceInTestExtension"
+  // is set to true.
+  isInBackgroundServiceWorkerTests() {
+    return ExtensionTestCommon.isInBackgroundServiceWorkerTests();
+  },
+};
+
 ExtensionTestUtils.loadExtension = function(ext) {
   // Cleanup functions need to be registered differently depending on
   // whether we're in browser chrome or plain mochitests.

toolkit/components/extensions/ExtensionTestCommon.jsm

@@ -236,6 +236,37 @@ function provide(obj, keys, value, override = false) {
 }
 
 ExtensionTestCommon = class ExtensionTestCommon {
+  /**
+   * Shortcut to more easily access WebExtensionPolicy.backgroundServiceWorkerEnabled
+   * from mochitest-plain tests.
+   *
+   * @returns {boolean} true if the background service worker are enabled.
+   */
+  static getBackgroundServiceWorkerEnabled() {
+    return WebExtensionPolicy.backgroundServiceWorkerEnabled;
+  }
+
+  /**
+   * A test helper mainly used to skip test tasks if running in "backgroundServiceWorker" test mode
+   * (e.g. while running test files shared across multiple test modes: e.g. in-process-webextensions,
+   * remote-webextensions, sw-webextensions etc.).
+   *
+   * The underlying pref "extension.backgroundServiceWorker.forceInTestExtension":
+   * - is set to true in the xpcshell-serviceworker.ini and mochitest-serviceworker.ini manifests
+   *   (and so it is going to be set to true while running the test files listed in those manifests)
+   * - when set to true, all test extension using a background script without explicitly listing it
+   *   in the test extension manifest will be automatically executed as background service workers
+   *   (instead of background scripts loaded in a background page)
+   *
+   * @returns {boolean} true if the test is running in "background service worker mode"
+   */
+  static isInBackgroundServiceWorkerTests() {
+    return Services.prefs.getBoolPref(
+      "extensions.backgroundServiceWorker.forceInTestExtension",
+      false
+    );
+  }
+
   /**
    * This code is designed to make it easy to test a WebExtension
    * without creating a bunch of files. Everything is contained in a
@@ -284,10 +315,22 @@ ExtensionTestCommon = class ExtensionTestCommon {
       delete manifest.host_permissions;
     }
 
+    if (data.useServiceWorker === undefined) {
+      // If we're force-testing service workers we will turn the background
+      // script part of ExtensionTestUtils test extensions into a background
+      // service worker.
+      data.useServiceWorker = ExtensionTestCommon.isInBackgroundServiceWorkerTests();
+    }
+
     if (data.background) {
       let bgScript = Services.uuid.generateUUID().number + ".js";
 
-      provide(manifest, ["background", "scripts"], [bgScript], true);
+      let scriptKey = data.useServiceWorker
+        ? ["background", "service_worker"]
+        : ["background", "scripts"];
+      let scriptVal = data.useServiceWorker ? bgScript : [bgScript];
+      provide(manifest, scriptKey, scriptVal, true);
+
       files[bgScript] = data.background;
     }
 

toolkit/components/extensions/child/ext-test.js

@@ -231,16 +231,24 @@ this.test = class extends ExtensionAPI {
 
           return promise.then(
             result => {
-              assertTrue(false, `Promise resolved, expected rejection: ${msg}`);
+              let message = `Promise resolved, expected rejection '${toSource(
+                expectedError
+              )}'`;
+              if (msg) {
+                message += `: ${msg}`;
+              }
+              assertTrue(false, message);
             },
             error => {
-              let errorMessage = toSource(error && error.message);
+              let expected = toSource(expectedError);
+              let message = `got '${toSource(error)}'`;
+              if (msg) {
+                message += `: ${msg}`;
+              }
 
               assertTrue(
                 errorMatches(error, expectedError, context),
-                `Promise rejected, expecting rejection to match ${toSource(
-                  expectedError
-                )}, got ${errorMessage}: ${msg}`
+                `Promise rejected, expecting rejection to match '${expected}', ${message}`
               );
             }
           );
@@ -250,15 +258,23 @@ this.test = class extends ExtensionAPI {
           try {
             func();
 
-            assertTrue(false, `Function did not throw, expected error: ${msg}`);
+            let message = `Function did not throw, expected error '${toSource(
+              expectedError
+            )}'`;
+            if (msg) {
+              message += `: ${msg}`;
+            }
+            assertTrue(false, message);
           } catch (error) {
-            let errorMessage = toSource(error && error.message);
+            let expected = toSource(expectedError);
+            let message = `got '${toSource(error)}'`;
+            if (msg) {
+              message += `: ${msg}`;
+            }
 
             assertTrue(
               errorMatches(error, expectedError, context),
-              `Function threw, expecting error to match ${toSource(
-                expectedError
-              )}, got ${errorMessage}: ${msg}`
+              `Function threw, expecting error to match '${expected}', ${message}`
             );
           }
         },

toolkit/components/extensions/moz.build

@@ -127,6 +127,8 @@ XPCSHELL_TESTS_MANIFESTS += [
 # in builds where they are enabled (currently only on Nightly builds).
 if CONFIG["MOZ_WEBEXT_WEBIDL_ENABLED"]:
     XPCSHELL_TESTS_MANIFESTS += ["test/xpcshell/webidl-api/xpcshell.ini"]
+    MOCHITEST_MANIFESTS += ["test/mochitest/mochitest-serviceworker.ini"]
+
 
 SPHINX_TREES["webextensions"] = "docs"
 

toolkit/components/extensions/test/mochitest/mochitest-serviceworker.ini

@@ -0,0 +1,15 @@
+[DEFAULT]
+tags = webextensions sw-webextensions
+skip-if =
+  !e10s             # Thunderbird does still run in non e10s mode (and so also with in-process-webextensions mode)
+  (os == 'android') # Bug 1620091: disable on android until extension process is done
+
+prefs =
+  extensions.webextensions.remote=true
+  extensions.backgroundServiceWorker.enabled=true
+  extensions.backgroundServiceWorker.forceInTestExtension=true
+
+dupe-manifest = true
+
+[test_verify_sw_mode.html]
+[test_ext_test.html]

toolkit/components/extensions/test/mochitest/test_ext_test.html

@@ -3,6 +3,7 @@
 <head>
   <title>Testing test</title>
   <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
   <script type="text/javascript" src="head.js"></script>
   <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css">
 </head>
@@ -43,9 +44,15 @@ function loadExtensionAndInterceptTest(extensionData) {
   return extension;
 }
 
+// NOTE: This test does not verify the behavior expected by calling the browser.test API methods.
+//
+// On the contrary it tests what messages ext-test.js sends to the parent process as a result of
+// processing different kind of parameters (e.g. how a dom element or a JS object with a custom
+// toString method are being serialized into strings).
+//
+// All browser.test calls results are intercepted by the test itself, see verifyTestResults for
+// the expectations of each browser.test call.
 function testScript() {
-  // Note: The result of these browser.test calls are intercepted by the test.
-  // See verifyTestResults for the expectations of each browser.test call.
   browser.test.notifyPass("dot notifyPass");
   browser.test.notifyFail("dot notifyFail");
   browser.test.log("dot log");
@@ -57,43 +64,36 @@ function testScript() {
 
   let obj = {};
   let arr = [];
-  let dom = document.createElement("body");
   browser.test.assertTrue(obj, "Object truthy");
   browser.test.assertTrue(arr, "Array truthy");
-  browser.test.assertTrue(dom, "Element truthy");
   browser.test.assertTrue(true, "True truthy");
   browser.test.assertTrue(false, "False truthy");
   browser.test.assertTrue(null, "Null truthy");
   browser.test.assertTrue(undefined, "Void truthy");
-  browser.test.assertTrue(false, document.createElement("html"));
 
   browser.test.assertFalse(obj, "Object falsey");
   browser.test.assertFalse(arr, "Array falsey");
-  browser.test.assertFalse(dom, "Element falsey");
   browser.test.assertFalse(true, "True falsey");
   browser.test.assertFalse(false, "False falsey");
   browser.test.assertFalse(null, "Null falsey");
   browser.test.assertFalse(undefined, "Void falsey");
-  browser.test.assertFalse(true, document.createElement("head"));
 
   browser.test.assertEq(obj, obj, "Object equality");
   browser.test.assertEq(arr, arr, "Array equality");
-  browser.test.assertEq(dom, dom, "Element equality");
   browser.test.assertEq(null, null, "Null equality");
   browser.test.assertEq(undefined, undefined, "Void equality");
 
   browser.test.assertEq({}, {}, "Object reference ineqality");
   browser.test.assertEq([], [], "Array reference ineqality");
-  browser.test.assertEq(dom, document.createElement("body"), "Element ineqality");
   browser.test.assertEq(null, undefined, "Null and void ineqality");
-  browser.test.assertEq(true, false, document.createElement("div"));
 
   obj = {
     toString() {
-      return "Dynamic toString forbidden";
+      return "Dynamic toString";
     },
   };
   browser.test.assertEq(obj, obj, "obj with dynamic toString()");
+
   browser.test.assertThrows(
     () => { throw new Error("dummy"); },
     /dummy2/,
@@ -107,11 +107,25 @@ function testScript() {
     () => {},
     /dummy/
   );
+
+  // Set of additional tests to only run on background page and content script
+  // (but skip on background service worker).
+  if (self === self.window) {
+    let dom = document.createElement("body");
+    browser.test.assertTrue(dom, "Element truthy");
+    browser.test.assertTrue(false, document.createElement("html"));
+    browser.test.assertFalse(dom, "Element falsey");
+    browser.test.assertFalse(true, document.createElement("head"));
+    browser.test.assertEq(dom, dom, "Element equality");
+    browser.test.assertEq(dom, document.createElement("body"), "Element ineqality");
+    browser.test.assertEq(true, false, document.createElement("div"));
+  }
+
   browser.test.sendMessage("Ran test at", location.protocol);
   browser.test.sendMessage("This is the last browser.test call");
 }
 
-function verifyTestResults(results, shortName, expectedProtocol) {
+function verifyTestResults(results, shortName, expectedProtocol, useServiceWorker) {
   let expectations = [
     ["test-done", true, "dot notifyPass"],
     ["test-done", false, "dot notifyFail"],
@@ -124,42 +138,72 @@ function verifyTestResults(results, shortName, expectedProtocol) {
 
     ["test-result", true, "Object truthy"],
     ["test-result", true, "Array truthy"],
-    ["test-result", true, "Element truthy"],
     ["test-result", true, "True truthy"],
     ["test-result", false, "False truthy"],
     ["test-result", false, "Null truthy"],
     ["test-result", false, "Void truthy"],
-    ["test-result", false, "[object HTMLHtmlElement]"],
 
     ["test-result", false, "Object falsey"],
     ["test-result", false, "Array falsey"],
-    ["test-result", false, "Element falsey"],
     ["test-result", false, "True falsey"],
     ["test-result", true, "False falsey"],
     ["test-result", true, "Null falsey"],
     ["test-result", true, "Void falsey"],
-    ["test-result", false, "[object HTMLHeadElement]"],
 
     ["test-eq", true, "Object equality", "[object Object]", "[object Object]"],
     ["test-eq", true, "Array equality", "", ""],
-    ["test-eq", true, "Element equality", "[object HTMLBodyElement]", "[object HTMLBodyElement]"],
     ["test-eq", true, "Null equality", "null", "null"],
     ["test-eq", true, "Void equality", "undefined", "undefined"],
 
     ["test-eq", false, "Object reference ineqality", "[object Object]", "[object Object] (different)"],
     ["test-eq", false, "Array reference ineqality", "", " (different)"],
-    ["test-eq", false, "Element ineqality", "[object HTMLBodyElement]", "[object HTMLBodyElement] (different)"],
     ["test-eq", false, "Null and void ineqality", "null", "undefined"],
+
+    [
+      "test-eq",
+      true,
+      "obj with dynamic toString()",
+      // - Privileged JS API Bindings: the ext-test.js module will get a XrayWrapper and so when
+      //   the object is being stringified the custom `toString()` method will not be called and
+      //   "[object Object]" is the value we expect.
+      // - WebIDL API Bindngs: the parameter is being serialized into a string on the worker thread,
+      //   the object is stringified using the worker principal and so there is no XrayWrapper
+      //   involved and the value expected is the value returned by the custom toString method the.
+      //   object does provide.
+      useServiceWorker ? "Dynamic toString" : "[object Object]",
+      useServiceWorker ? "Dynamic toString" : "[object Object]",
+    ],
+
+    [
+      "test-result", false,
+      "Function threw, expecting error to match '/dummy2/', got \'Error: dummy\': intentional failure"
+    ],
+    [
+      "test-result", false,
+      "Function threw, expecting error to match '/dummy3/', got \'Error: dummy2\'"
+    ],
+    [
+      "test-result", false,
+      "Function did not throw, expected error '/dummy/'"
+    ],
+  ];
+
+  if (!useServiceWorker) {
+    expectations.push(...[
+      ["test-result", true, "Element truthy"],
+      ["test-result", false, "[object HTMLHtmlElement]"],
+      ["test-result", false, "Element falsey"],
+      ["test-result", false, "[object HTMLHeadElement]"],
+      ["test-eq", true, "Element equality", "[object HTMLBodyElement]", "[object HTMLBodyElement]"],
+      ["test-eq", false, "Element ineqality", "[object HTMLBodyElement]", "[object HTMLBodyElement] (different)"],
       ["test-eq", false, "[object HTMLDivElement]", "true", "false"],
+    ]);
+  }
 
-    ["test-eq", true, "obj with dynamic toString()", "[object Object]", "[object Object]"],
-    ["test-result", false, "Function threw, expecting error to match /dummy2/, got \"dummy\": intentional failure"],
-    ["test-result", false, "Function threw, expecting error to match /dummy3/, got \"dummy2\": null"],
-    ["test-result", false, "Function did not throw, expected error: null"],
-
+  expectations.push(...[
     ["test-message", "Ran test at", expectedProtocol],
     ["test-message", "This is the last browser.test call"],
-  ];
+  ]);
 
   expectations.forEach((expectation, i) => {
     let msg = expectation.slice(2).join(" - ");
@@ -171,12 +215,41 @@ function verifyTestResults(results, shortName, expectedProtocol) {
 add_task(async function test_test_in_background() {
   let extensionData = {
     background: `(${testScript})()`,
+    // This test case should never run the background script in a worker,
+    // even if this test file is running when "extensions.backgroundServiceWorker.forceInTest"
+    // pref is true
+    useServiceWorker: false,
   };
 
   let extension = loadExtensionAndInterceptTest(extensionData);
   await extension.startup();
   let results = await extension.awaitResults();
-  verifyTestResults(results, "background page", "moz-extension:");
+  verifyTestResults(results, "background page", "moz-extension:", false);
+  await extension.unload();
+});
+
+add_task(async function test_test_in_background_service_worker() {
+  if (!ExtensionTestUtils.isInBackgroundServiceWorkerTests()) {
+    is(
+      ExtensionTestUtils.getBackgroundServiceWorkerEnabled(),
+      false,
+      "This test should only be skipped with background service worker disabled"
+    )
+    info("Test intentionally skipped on 'extensions.backgroundServiceWorker.enabled=false'");
+    return;
+  }
+
+  let extensionData = {
+    background: `(${testScript})()`,
+    // This test case should always run the background script in a worker,
+    // or be skipped if the background service worker is disabled by prefs.
+    useServiceWorker: true,
+  };
+
+  let extension = loadExtensionAndInterceptTest(extensionData);
+  await extension.startup();
+  let results = await extension.awaitResults();
+  verifyTestResults(results, "background service worker", "moz-extension:", true);
   await extension.unload();
 });
 
@@ -198,7 +271,7 @@ add_task(async function test_test_in_content_script() {
   let win = window.open("file_sample.html");
   let results = await extension.awaitResults();
   win.close();
-  verifyTestResults(results, "content script", "http:");
+  verifyTestResults(results, "content script", "http:", false);
   await extension.unload();
 });
 </script>

toolkit/components/extensions/test/mochitest/test_verify_sw_mode.html

@@ -0,0 +1,24 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Verify WebExtension background service worker mode</title>
+  <meta charset="utf-8">
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+  "use strict";
+  // This test ensures we are running with the proper settings.
+  const {WebExtensionPolicy} = SpecialPowers.Cu.getGlobalForObject(SpecialPowers.Services);
+  SimpleTest.ok(WebExtensionPolicy.useRemoteWebExtensions, "extensions running remote");
+  SimpleTest.ok(!WebExtensionPolicy.isExtensionProcess, "testing from remote process");
+  SimpleTest.ok(WebExtensionPolicy.backgroundServiceWorkerEnabled, "extensions background service worker enabled");
+  SimpleTest.ok(AppConstants.MOZ_WEBEXT_WEBIDL_ENABLED, "extensions API webidl bindings enabled");
+</script>
+
+</body>
+</html>

toolkit/components/extensions/webidl-api/ExtensionTest.cpp

@@ -322,7 +322,7 @@ MOZ_CAN_RUN_SCRIPT void ExtensionTest::AssertThrows(
   }
 
   if (NS_WARN_IF(!AssertMatchInternal(aCx, exn, aExpectedError,
-                                      u"Function did throw, expected error"_ns,
+                                      u"Function threw, expecting error"_ns,
                                       aMessage, nullptr, aRv))) {
     ThrowUnexpectedError(aCx, aRv);
   }