Initial implementation for ListThumbnailLoader.

ui/file_manager/file_manager/foreground/js/list_thumbnail_loader_unittest.js

Index: ui/file_manager/file_manager/foreground/js/list_thumbnail_loader_unittest.js
diff --git a/ui/file_manager/file_manager/foreground/js/list_thumbnail_loader_unittest.js b/ui/file_manager/file_manager/foreground/js/list_thumbnail_loader_unittest.js
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index 0000000000000000000000000000000000000000..5c288ce4d4baaa2dda54841e1414058a6d8e0416
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+++ b/ui/file_manager/file_manager/foreground/js/list_thumbnail_loader_unittest.js
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+// Copyright 2015 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.
+
+/**
+ * Wait until the condition is met.
+ *
+ * @param {function()} condition Condition.
+ * @return {Promise} A promise which is resolved when condition is met.
+ */
+function waitUntil(condition) {
+  return new Promise(function(resolve, reject) {
+    var checkCondition = function() {
+      if (condition())
+        resolve();
+      else
+        setTimeout(checkCondition, 100);
+    };
+    checkCondition();
+  });
+}
+
+/**
+ * Generates a data url of a sample image for testing.
+ * TODO(yawano) Consider to share image generation logic with
+ *     gallery/js/image_editor/test_util.js.
+ *
+ * @param {Document} document Document.
+ * @return {string} Data url of a sample image.
+ */
+function generateSampleImageDataUrl(document) {
+  var canvas = document.createElement('canvas');
+  canvas.width = 160;
+  canvas.height = 160;
+
+  var context = canvas.getContext('2d');
+  context.fillStyle = 'black';
+  context.fillRect(0, 0, 80, 80);
+  context.fillRect(80, 80, 80, 80);
+
+  return canvas.toDataURL('image/jpeg', 0.5);
+}
+
+/**
+ * Story test for list thumbnail loader.
+ */
+function testStory(callback) {
+  ListThumbnailLoader.NUM_OF_MAX_ACTIVE_TASKS = 2;
+  MockThumbnailLoader.setTestImageDataUrl(generateSampleImageDataUrl(document));
+
+  var getOneCallbacks = {};
+  var metadataCache = {
+    getOne: function(entry, type, callback) {
+      getOneCallbacks[entry.toURL()] = callback;
+    }
+  };
+
+  var fileListModel = new FileListModel(metadataCache);
+
+  var listThumbnailLoader = new ListThumbnailLoader(fileListModel,
+      metadataCache, document, MockThumbnailLoader);
+  var thumbnailLoadedEvents = [];
+  listThumbnailLoader.addEventListener('thumbnailLoaded', function(event) {
+    thumbnailLoadedEvents.push(event);
+  });
+
+  // Add 1 directory and 5 entries.
+  var fileSystem = new MockFileSystem('volume-id');
+  var directory1 = new MockDirectoryEntry(fileSystem, '/TestDirectory');
+  var entry1 = new MockEntry(fileSystem, '/Test1.jpg');
+  var entry2 = new MockEntry(fileSystem, '/Test2.jpg');
+  var entry3 = new MockEntry(fileSystem, '/Test3.jpg');
+  var entry4 = new MockEntry(fileSystem, '/Test4.jpg');
+  var entry5 = new MockEntry(fileSystem, '/Test5.jpg');
+  fileListModel.push(directory1, entry1, entry2, entry3, entry4, entry5);
+
+  // Set high priority range to 0 - 2.
+  listThumbnailLoader.setHighPriorityRange(0, 2);
+
+  // Assert that 2 fetch tasks are running.
+  assertArrayEquals([entry1.toURL(), entry2.toURL()],
+      Object.keys(getOneCallbacks));
+
+  // Fails to get thumbnail from cache for Test2.jpg.
+  assertEquals(null, listThumbnailLoader.getThumbnailFromCache(entry2));
+
+  // Set high priority range to 4 - 6.
+  listThumbnailLoader.setHighPriorityRange(4, 6);
+
+  // Assert that no new tasks are enqueued.
+  assertArrayEquals([entry1.toURL(), entry2.toURL()],
+      Object.keys(getOneCallbacks));
+
+  // Resolve metadataCache.getOne for Test2.jpg.
+  getOneCallbacks[entry2.toURL()]();
+  delete getOneCallbacks[entry2.toURL()];
+
+  reportPromise(waitUntil(function() {
+    // Assert that thumbnailLoaded event is fired for Test2.jpg.
+    return thumbnailLoadedEvents.length === 1;
+  }).then(function() {
+    var event = thumbnailLoadedEvents.shift();
+    assertEquals('filesystem:volume-id/Test2.jpg', event.fileUrl);
+    assertTrue(event.dataUrl.length > 0);
+    assertEquals(160, event.width);
+    assertEquals(160, event.height);
+
+    // Since thumbnail of Test2.jpg is loaded into the cache,
+    // getThumbnailFromCache returns thumbnail for the image.
+    var thumbnail = listThumbnailLoader.getThumbnailFromCache(entry2);
+    assertEquals('filesystem:volume-id/Test2.jpg', thumbnail.fileUrl);
+    assertTrue(thumbnail.dataUrl.length > 0);
+    assertEquals(160, thumbnail.width);
+    assertEquals(160, thumbnail.height);
+
+    // Assert that new task is enqueued.
+    return waitUntil(function() {
+      return !!getOneCallbacks[entry1.toURL()] &&
+          !!getOneCallbacks[entry4.toURL()] &&
+          Object.keys(getOneCallbacks).length === 2;
+    });
+  }).then(function() {
+    // Set high priority range to 2 - 4.
+    listThumbnailLoader.setHighPriorityRange(2, 4);
+
+    // Resolve metadataCache.getOne for Test1.jpg.
+    getOneCallbacks[entry1.toURL()]();
+    delete getOneCallbacks[entry1.toURL()];
+
+    // Assert that task for (Test3.jpg) is enqueued.
+    return waitUntil(function() {
+      return !!getOneCallbacks[entry3.toURL()] &&
+          !!getOneCallbacks[entry4.toURL()] &&
+          Object.keys(getOneCallbacks).length === 2;
+    });
+  }).then(function() {
+    // Cache is deleted when the item is removed from the list.
+    var result = fileListModel.splice(2, 1); // Remove Test2.jpg.
+
+    // Fail to fetch thumbnail from cache.
+    return waitUntil(function() {
+      return listThumbnailLoader.getThumbnailFromCache(entry2) === null;
+    });
+  }), callback);
+}