Support writing files app integration tests directly as async functions.

Convert keyboardSelectDriveDirectoryTree as an example.

Bug: 909056
Change-Id: Ie08b6a787f4d9397d832f435b8f650d647e61ceb
Reviewed-on: https://chromium-review.googlesource.com/c/1349157
Commit-Queue: Sam McNally <sammc@chromium.org>
Reviewed-by: Noel Gordon <noel@chromium.org>
Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612062}

ui/file_manager/integration_tests/.eslintrc.js

+// Copyright 2018 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+module.exports = {
+  'parserOptions': {'ecmaVersion': 8},
+};

ui/file_manager/integration_tests/file_manager/background.js

@@ -398,7 +398,7 @@ function setupAndWaitUntilReady(
     driveEntriesPromise,
     detailedTablePromise
   ]).then(function(results) {
-    result = {windowId: results[0], fileList: results[3]};
+    result = {windowId: results[0], fileList: results[3], appId: results[0]};
     return remoteCall.waitFor('isFileManagerLoaded', result.windowId, true);
   }).then(() => {
     if (opt_callback)
@@ -412,9 +412,10 @@ function setupAndWaitUntilReady(
 /**
  * Verifies if there are no Javascript errors in any of the app windows.
  * @param {function()} Completion callback.
+ * @return {Promise} Promise to be fulfilled on completion.
  */
 function checkIfNoErrorsOccured(callback) {
-  checkIfNoErrorsOccuredOnApp(remoteCall, callback);
+  return checkIfNoErrorsOccuredOnApp(remoteCall, callback);
 }
 
 /**
@@ -444,6 +445,46 @@ function getFileType(fileListEntry) {
   return fileListEntry[2];
 }
 
+/**
+ * A value that when returned by an async test indicates that app errors should
+ * not be checked following completion of the test.
+ */
+const IGNORE_APP_ERRORS = Symbol('IGNORE_APP_ERRORS');
+
+/**
+ * For async function tests, wait for the test to complete, check for app errors
+ * unless skipped, and report the results.
+ * @param {Promise} resultPromise A promise that resolves with the test result.
+ * @private
+ */
+async function awaitAsyncTestResult(resultPromise) {
+  // Hold a pending callback to ensure the test doesn't complete early.
+  const passCallback = chrome.test.callbackPass();
+
+  try {
+    const result = await resultPromise;
+    if (result != IGNORE_APP_ERRORS) {
+      await checkIfNoErrorsOccured();
+    }
+  } catch (error) {
+    // If the test has failed, ignore the exception and return.
+    if (error == 'chrome.test.failure') {
+      return;
+    }
+
+    // Otherwise, report the exception as a test failure. chrome.test.fail()
+    // emits an exception; catch it to avoid spurious logging about an uncaught
+    // exception.
+    try {
+      chrome.test.fail(error.stack || error);
+    } catch (_) {
+      return;
+    }
+  }
+
+  passCallback();
+}
+
 /**
  * Namespace for test cases.
  */
@@ -489,8 +530,10 @@ window.addEventListener('load', function() {
       test.generatedName = testCaseName;
       var testCaseSymbol = Symbol(testCaseName);
       var testCase = {
-        [testCaseSymbol] :() => {
-          return test();
+        [testCaseSymbol]: () => {
+          const result = test();
+          return (result instanceof Promise) ? awaitAsyncTestResult(result) :
+                                               result;
         },
       };
       // Run the test.

ui/file_manager/integration_tests/file_manager/keyboard_operations.js

@@ -359,57 +359,33 @@ testcase.renameNewFolderDrive = function() {
  * Test that selecting "Google Drive" in the directory tree with the keyboard
  * expands it and selects "My Drive".
  */
-testcase.keyboardSelectDriveDirectoryTree = function() {
-  let appId = null;
+testcase.keyboardSelectDriveDirectoryTree = async function() {
+  // Open Files app.
+  const {appId} = await setupAndWaitUntilReady(
+      null, RootPath.DOWNLOADS, null, [ENTRIES.world], [ENTRIES.hello]);
 
-  StepsRunner.run([
-    // Open Files app.
-    function() {
-      setupAndWaitUntilReady(
-          null, RootPath.DOWNLOADS, this.next, [ENTRIES.world],
-          [ENTRIES.hello]);
-    },
-    // Focus the directory tree.
-    function(result) {
-      appId = result.windowId;
-      remoteCall.callRemoteTestUtil('focus', appId, ['#directory-tree'])
-          .then(this.next);
-    },
-    // Select Google Drive in the directory tree; it's the last item.
-    function() {
-      return remoteCall
-          .fakeKeyDown(appId, '#directory-tree', 'End', false, false, false)
-          .then(this.next);
-    },
-    // Ensure it's selected.
-    function() {
-      remoteCall.waitForElement(appId, ['.drive-volume [selected]'])
-          .then(this.next);
-    },
-    // Activate it.
-    function() {
-      return remoteCall
-          .fakeKeyDown(
-              appId, '#directory-tree .drive-volume', 'Enter', false, false,
-              false)
-          .then(this.next);
-    },
-    // It should have expanded.
-    function() {
-      remoteCall
-          .waitForElement(appId, ['.drive-volume .tree-children[expanded]'])
-          .then(this.next);
-    },
-    // My Drive should be selected.
-    function() {
-      remoteCall
-          .waitForElement(appId, ['[full-path-for-testing="/root"] [selected]'])
-          .then(this.next);
-    },
-    function() {
-      checkIfNoErrorsOccured(this.next);
-    },
-  ]);
+  // Focus the directory tree.
+  await remoteCall.callRemoteTestUtil('focus', appId, ['#directory-tree']);
+
+  // Select Google Drive in the directory tree; as of the time of writing, it's
+  // the last item so this happens to work.
+  await remoteCall.fakeKeyDown(
+      appId, '#directory-tree', 'End', false, false, false);
+
+  // Ensure it's selected.
+  await remoteCall.waitForElement(appId, ['.drive-volume [selected]']);
+
+  // Activate it.
+  await remoteCall.fakeKeyDown(
+      appId, '#directory-tree .drive-volume', 'Enter', false, false, false);
+
+  // It should have expanded.
+  await remoteCall.waitForElement(
+      appId, ['.drive-volume .tree-children[expanded]']);
+
+  // My Drive should be selected.
+  await remoteCall.waitForElement(
+      appId, ['[full-path-for-testing="/root"] [selected]']);
 };
 
 /**

ui/file_manager/integration_tests/test_util.js

@@ -49,12 +49,15 @@ function wait(time) {
  * asserting the count returned by the app.getErrorCount remote call.
  * @param {!RemoteCall} app RemoteCall interface to the app window.
  * @param {function()} callback Completion callback.
+ * @return {Promise} Promise to be fulfilled on completion.
  */
 function checkIfNoErrorsOccuredOnApp(app, callback) {
   var countPromise = app.callRemoteTestUtil('getErrorCount', null, []);
-  countPromise.then(function(count) {
+  return countPromise.then(function(count) {
     chrome.test.assertEq(0, count, 'The error count is not 0.');
-    callback();
+    if (callback) {
+      callback();
+    }
   });
 }