Files.app: Handles corner cases in NewMetadataProvider.

ui/file_manager/file_manager/foreground/js/metadata/new_metadata_provider_unittest.js

Index: ui/file_manager/file_manager/foreground/js/metadata/new_metadata_provider_unittest.js
diff --git a/ui/file_manager/file_manager/foreground/js/metadata/new_metadata_provider_unittest.js b/ui/file_manager/file_manager/foreground/js/metadata/new_metadata_provider_unittest.js
index 533be6097550109a147604fe79546c6afdaa135c..be81c33d6775d005927e687de8ffcdae45846b23 100644
--- a/ui/file_manager/file_manager/foreground/js/metadata/new_metadata_provider_unittest.js
+++ b/ui/file_manager/file_manager/foreground/js/metadata/new_metadata_provider_unittest.js
@@ -3,7 +3,7 @@
 // found in the LICENSE file.
 
 function TestMetadataProvider(cache) {
-  NewMetadataProvider.call(this, cache);
+  NewMetadataProvider.call(this, cache, ['property', 'propertyA', 'propertyB']);
   this.requestCount = 0;
 }
 
@@ -22,6 +22,18 @@ TestMetadataProvider.prototype.getImpl = function(requests) {
   }));
 };
 
+function TestEmptyMetadataProvider(cache) {
+  NewMetadataProvider.call(this, cache, ['property']);
+}
+
+TestEmptyMetadataProvider.prototype.__proto__ = NewMetadataProvider.prototype;
+
+TestEmptyMetadataProvider.prototype.getImpl = function(requests) {
+  return Promise.resolve(requests.map(function() {
+    return {};
+  }));
+};
+
 var entryA = {
   toURL: function() { return "filesystem://A"; }
 };
@@ -113,3 +125,20 @@ function testNewMetadataProviderGetCache(callback) {
     assertEquals('filesystem://A:property', cache[0].property);
   }), callback);
 }
+
+function testNewMetadataProviderUnknownProperty() {
+  var cache = new MetadataProviderCache();
+  var provider = new TestMetadataProvider(cache);
+  assertThrows(function() {
+    provider.get([entryA], ['unknown']);
+  });
+}
+
+function testNewMetadataProviderEmptyResult(callback) {
+  var cache = new MetadataProviderCache();
+  var provider = new TestEmptyMetadataProvider(cache);
+  // getImpl returns empty result.
+  reportPromise(provider.get([entryA], ['property']).then(function(results) {
+    assertEquals(undefined, results[0].property);
+  }), callback);
+}