Speed-up QuickView openQuickView browser test

The test tests that Quick View opens by the usual method: user presses
the space key on a selected file.

Change the test to use a text file, rather than a PNG image, to remove
image decode and rescale costs from the test-time.

Also put all tests steps in a StepRunner group, so that all test steps
can be debugged using the step runner browser test flag. Document each
of the steps.

Bug: 851888
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: Ief21de93e9496f463506d2ae22ab28db76c087ef
Reviewed-on: https://chromium-review.googlesource.com/1097041Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Commit-Queue: Noel Gordon <noel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#566699}

ui/file_manager/integration_tests/file_manager/quick_view.js

@@ -4,43 +4,38 @@
 
 'use strict';
 
-function openQuickViewSteps(appId, filename) {
-  var caller = getCaller();
+function openQuickViewSteps(appId, name) {
+  let caller = getCaller();
+
+  function checkQuickViewElementsDisplayBlock(elements) {
+    const haveElements = Array.isArray(elements) && elements.length !== 0;
+    if (!haveElements || elements[0].styles.display !== 'block')
+      return pending(caller, 'Waiting for Quick View to open.');
+    return;
+  }
+
   return [
-    function(results) {
-      remoteCall.callRemoteTestUtil('selectFile', appId, [filename], this.next);
+    // Select file |name| in the file list.
+    function() {
+      remoteCall.callRemoteTestUtil('selectFile', appId, [name], this.next);
     },
-    function(results) {
-      chrome.test.assertTrue(results);
-      // Press Space key.
-      remoteCall.callRemoteTestUtil(
-          'fakeKeyDown', appId,
-          ['#file-list', ' ', ' ', false, false, false], this.next);
+    // Press the space key.
+    function(result) {
+      chrome.test.assertTrue(!!result, 'selectFile failed');
+      const space = ['#file-list', ' ', ' ', false, false, false];
+      remoteCall.callRemoteTestUtil('fakeKeyDown', appId, space, this.next);
     },
-    function(results) {
-      chrome.test.assertTrue(results);
-
-      // Wait until Quick View is displayed.
+    // Check: the Quick View element should be shown.
+    function(result) {
+      chrome.test.assertTrue(!!result, 'fakeKeyDown failed');
       repeatUntil(function() {
+        const elements = ['#quick-view', '#dialog'];
         return remoteCall
             .callRemoteTestUtil(
-                'deepQueryAllElements', appId,
-                [['#quick-view', '#dialog'], null, ['display']])
-            .then(function(results) {
-              if (results.length === 0 ||
-                  results[0].styles.display === 'none') {
-                return pending(caller, 'Quick View is not opened yet.');
-              }
-              return results;
-            });
+                'deepQueryAllElements', appId, [elements, null, ['display']])
+            .then(checkQuickViewElementsDisplayBlock);
       }).then(this.next);
     },
-    function(results) {
-      chrome.test.assertEq(1, results.length);
-      // Check Quick View dialog is displayed.
-      chrome.test.assertEq('block', results[0].styles.display);
-      checkIfNoErrorsOccured(this.next);
-    },
   ];
 }
 
@@ -71,13 +66,26 @@ function closeQuickViewSteps(appId) {
 }
 
 /**
- * Tests opening Quick View.
+ * Tests opening Quick View on a local downloads file.
  */
 testcase.openQuickView = function() {
-  setupAndWaitUntilReady(null, RootPath.DOWNLOADS).then(function(results) {
-    StepsRunner.run(
-        openQuickViewSteps(results.windowId, 'My Desktop Background.png'));
-  });
+  let appId;
+
+  StepsRunner.run([
+    // Open Files app on local downloads.
+    function() {
+      setupAndWaitUntilReady(null, RootPath.DOWNLOADS, this.next);
+    },
+    // Open a file in Quick View.
+    function(results) {
+      appId = results.windowId;
+      const openSteps = openQuickViewSteps(appId, ENTRIES.hello.nameText);
+      StepsRunner.run(openSteps).then(this.next);
+    },
+    function() {
+      checkIfNoErrorsOccured(this.next);
+    },
+  ]);
 };
 
 /**