Call FetchImageCallback asynchronously when no thumbnail exists

components/ntp_snippets/content_suggestions_service_unittest.cc

 // Copyright 2016 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.
 
 #include "components/ntp_snippets/content_suggestions_service.h"
 
 #include <memory>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
+#include "base/message_loop/message_loop.h"
+#include "base/run_loop.h"
 #include "base/strings/string_number_conversions.h"
 #include "components/ntp_snippets/category_status.h"
 #include "components/ntp_snippets/content_suggestion.h"
 #include "components/ntp_snippets/content_suggestions_provider.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/gfx/image/image.h"
 
+using testing::ByRef;
+using testing::Const;
+using testing::ElementsAre;
 using testing::Eq;
+using testing::InvokeWithoutArgs;
+using testing::IsEmpty;
 using testing::IsNull;
+using testing::Mock;
 using testing::NotNull;
-using testing::IsEmpty;
-using testing::ElementsAre;
 using testing::Property;
-using testing::Const;
-using testing::Mock;
-using testing::ByRef;
 using testing::_;
 
 namespace ntp_snippets {
 
 namespace {
 
 // Returns a suggestion instance for testing.
 ContentSuggestion CreateSuggestion(int number) {
   return ContentSuggestion(
       base::IntToString(number),
@@ skipping 213 matching lines @@
 
   EXPECT_CALL(*provider1, FetchSuggestionImage(suggestion_id, _)).Times(1);
   EXPECT_CALL(*provider2, FetchSuggestionImage(_, _)).Times(0);
   service()->FetchSuggestionImage(
       suggestion_id, base::Bind(&ContentSuggestionsServiceTest::OnImageFetched,
                                 base::Unretained(this)));
 }
 
 TEST_F(ContentSuggestionsServiceTest,
        ShouldCallbackEmptyImageForUnavailableProvider) {
+  // Setup the current thread's MessageLoop.
+  base::MessageLoop message_loop;
+
+  base::RunLoop run_loop;
   std::string suggestion_id = "TestID";
   EXPECT_CALL(*this, OnImageFetched(suggestion_id,
-                                    Property(&gfx::Image::IsEmpty, Eq(true))));
+                                    Property(&gfx::Image::IsEmpty, Eq(true))))
+      .WillOnce(InvokeWithoutArgs(&run_loop, &base::RunLoop::Quit));
   service()->FetchSuggestionImage(
       suggestion_id, base::Bind(&ContentSuggestionsServiceTest::OnImageFetched,
                                 base::Unretained(this)));
+  run_loop.Run();
 }
 
 TEST_F(ContentSuggestionsServiceTest, ShouldRedirectDismissSuggestion) {
   Category articles_category = FromKnownCategory(KnownCategories::ARTICLES);
   Category offline_pages_category =
       FromKnownCategory(KnownCategories::OFFLINE_PAGES);
   MockProvider* provider1 = MakeProvider(articles_category);
   MockProvider* provider2 = MakeProvider(offline_pages_category);
 
   provider2->FireSuggestionsChanged(offline_pages_category, {11});
@@ skipping 62 matching lines @@
   Mock::VerifyAndClearExpectations(&observer);
 
   // Shutdown the service
   EXPECT_CALL(observer, ContentSuggestionsServiceShutdown());
   service()->Shutdown();
   service()->RemoveObserver(&observer);
   // The service will receive two Shutdown() calls.
 }
 
 }  // namespace ntp_snippets