Files.app: Add model classes to manage cache states of new MetadataCache.

ui/file_manager/file_manager/foreground/js/metadata/metadata_cache_item_unittest.js

Index: ui/file_manager/file_manager/foreground/js/metadata/metadata_cache_item_unittest.js
diff --git a/ui/file_manager/file_manager/foreground/js/metadata/metadata_cache_item_unittest.js b/ui/file_manager/file_manager/foreground/js/metadata/metadata_cache_item_unittest.js
new file mode 100644
index 0000000000000000000000000000000000000000..d1815a8c7f4bb401aa68a0974c1cc74137b084fe
--- /dev/null
+++ b/ui/file_manager/file_manager/foreground/js/metadata/metadata_cache_item_unittest.js
@@ -0,0 +1,49 @@
+// 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.
+
+function testMetadataCacheItemBasic() {
+  var item = new MetadataCacheItem();
+  var loadRequested = item.startRequests(1, ['propertyA']);
+  assertEquals(1, loadRequested.length);
+  assertEquals('propertyA', loadRequested[0]);
+
+  assertTrue(item.storeProperties(1, {propertyA: 'value'}));
+
+  var result = item.get(['propertyA']);
+  assertEquals('value', result.propertyA);
+}
+
+function testMetadataCacheItemAvoidDoubleLoad() {
+  var item = new MetadataCacheItem();
+  item.startRequests(1, ['propertyA']);
+  var loadRequested = item.startRequests(2, ['propertyA']);
+  assertEquals(0, loadRequested.length);
+
+  assertTrue(item.storeProperties(1, {propertyA: 'value'}));
+
+  var result = item.get(['propertyA']);
+  assertEquals('value', result.propertyA);
+}
+
+function testMetadataCacheItemInvalidate() {
+  var item = new MetadataCacheItem();
+  item.startRequests(1, ['propertyA']);
+  item.invalidate(2);
+  assertFalse(item.storeProperties(1, {propertyA: 'value'}));
+
+  var loadRequested = item.startRequests(3, ['propertyA']);
+  assertEquals(1, loadRequested.length);
+}
+
+function testMetadataCacheItemStoreInReverseOrder() {
+  var item = new MetadataCacheItem();
+  item.startRequests(1, ['propertyA']);
+  item.startRequests(2, ['propertyA']);
+
+  assertTrue(item.storeProperties(2, {propertyA: 'value2'}));
+  assertFalse(item.storeProperties(1, {propertyA: 'value1'}));
+
+  var result = item.get(['propertyA']);
+  assertEquals('value2', result.propertyA);
+}