[NTP Snippets] Add unit tests for NTPSnippetsFetcher

components/ntp_snippets/ntp_snippets_fetcher_unittest.cc

Index: components/ntp_snippets/ntp_snippets_fetcher_unittest.cc
diff --git a/components/ntp_snippets/ntp_snippets_fetcher_unittest.cc b/components/ntp_snippets/ntp_snippets_fetcher_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..47cc5d4546e385e83fb856527114dd4aafa7d0b1
--- /dev/null
+++ b/components/ntp_snippets/ntp_snippets_fetcher_unittest.cc
@@ -0,0 +1,129 @@
+// 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/ntp_snippets_fetcher.h"
+
+#include "base/message_loop/message_loop.h"
+#include "base/run_loop.h"
+#include "base/thread_task_runner_handle.h"
+#include "net/url_request/test_url_fetcher_factory.h"
+#include "net/url_request/url_request_test_util.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace ntp_snippets {
+namespace {
+
+using testing::IsNull;
+using testing::NotNull;
+
+const char kTestContentSnippetsServerUrl[] =
+    "https://chromereader-pa.googleapis.com/v1/fetch?key=dummytoken";
+
+class MockSnippetsAvailableCallback {
+ public:
+  MOCK_METHOD2(Run, void(const std::string& snippets_json,
+                         const std::string& status_message));
+};
+
+class NTPSnippetsFetcherTest : public testing::Test {
+ public:
+  NTPSnippetsFetcherTest()
+      : fake_url_fetcher_factory_(/*default_factory=*/nullptr),
+        snippets_fetcher_(scoped_refptr<base::SequencedTaskRunner>(),
+                          scoped_refptr<net::TestURLRequestContextGetter>(
+                              new net::TestURLRequestContextGetter(
+                                  base::ThreadTaskRunnerHandle::Get())),
+                          /*is_stable_channel=*/true) {
+    snippets_fetcher_subscription_ = snippets_fetcher_.AddCallback(
+        base::Bind(&MockSnippetsAvailableCallback::Run,
+                   base::Unretained(&mock_callback_)));
+  }
+
+  NTPSnippetsFetcher& snippets_fetcher() { return snippets_fetcher_; }
+
+  net::FakeURLFetcherFactory& fake_url_fetcher_factory() {
+    return fake_url_fetcher_factory_;
+  }
+
+  MockSnippetsAvailableCallback& mock_callback() { return mock_callback_; }
+
+ private:
+  // Instantiation of factory automatically sets itself as URLFetcher's factory.
+  net::FakeURLFetcherFactory fake_url_fetcher_factory_;
+  // Needed to use ThreadTaskRunnerHandle.
+  base::MessageLoop message_loop_;
+  NTPSnippetsFetcher snippets_fetcher_;
+  MockSnippetsAvailableCallback mock_callback_;
+  std::unique_ptr<
+      NTPSnippetsFetcher::SnippetsAvailableCallbackList::Subscription>
+      snippets_fetcher_subscription_;
+
+  DISALLOW_COPY_AND_ASSIGN(NTPSnippetsFetcherTest);
+};
+
+TEST_F(NTPSnippetsFetcherTest, ShouldNotFetchOnCreation) {
+  // The lack of registered baked in responses would cause any fetch to fail.
+  base::RunLoop().RunUntilIdle();
+}
+
+TEST_F(NTPSnippetsFetcherTest, ShouldFetchSuccessfully) {
+  const std::string json_str = "{ \"recos\": [] }";
+  fake_url_fetcher_factory().SetFakeResponse(
+      GURL(kTestContentSnippetsServerUrl),
+      /*data=*/json_str, net::HTTP_OK, net::URLRequestStatus::SUCCESS);
+  EXPECT_CALL(mock_callback(), Run(/*snippets_json=*/json_str,
+                                   /*status_message=*/std::string()))
+      .Times(1);
+  snippets_fetcher().FetchSnippets(/*hosts=*/std::set<std::string>(),
+                                   /*count=*/1);
+  base::RunLoop().RunUntilIdle();
+}
+
+TEST_F(NTPSnippetsFetcherTest, ShouldReportUrlStatusError) {
+  fake_url_fetcher_factory().SetFakeResponse(
+      GURL(kTestContentSnippetsServerUrl),
+      /*data=*/std::string(), net::HTTP_NOT_FOUND,
+      net::URLRequestStatus::FAILED);
+  EXPECT_CALL(mock_callback(),
+              Run(/*snippets_json=*/std::string(),
+                  /*status_message=*/"URLRequestStatus error -2"))
+      .Times(1);
+  snippets_fetcher().FetchSnippets(/*hosts=*/std::set<std::string>(),
+                                   /*count=*/1);
+  base::RunLoop().RunUntilIdle();
+}
+
+TEST_F(NTPSnippetsFetcherTest, ShouldReportHttpError) {
+  fake_url_fetcher_factory().SetFakeResponse(
+      GURL(kTestContentSnippetsServerUrl),
+      /*data=*/std::string(), net::HTTP_NOT_FOUND,
+      net::URLRequestStatus::SUCCESS);
+  EXPECT_CALL(mock_callback(), Run(/*snippets_json=*/std::string(),
+                                   /*status_message=*/"HTTP error 404"))
+      .Times(1);
+  snippets_fetcher().FetchSnippets(/*hosts=*/std::set<std::string>(),
+                                   /*count=*/1);
+  base::RunLoop().RunUntilIdle();
+}
+
+TEST_F(NTPSnippetsFetcherTest, ShouldCancelOngoingFetch) {
+  const std::string json_str = "{ \"recos\": [] }";
+  fake_url_fetcher_factory().SetFakeResponse(
+      GURL(kTestContentSnippetsServerUrl),
+      /*data=*/json_str, net::HTTP_OK, net::URLRequestStatus::SUCCESS);
+  EXPECT_CALL(mock_callback(), Run(/*snippets_json=*/json_str,
+                                   /*status_message=*/std::string()))
+      .Times(1);
+  snippets_fetcher().FetchSnippets(/*hosts=*/std::set<std::string>(),
+                                   /*count=*/1);
+  // Second call to FetchSnippets() overrides/cancels the previous. Callback is
+  // expected to be called once.
+  snippets_fetcher().FetchSnippets(/*hosts=*/std::set<std::string>(),
+                                   /*count=*/1);
+  base::RunLoop().RunUntilIdle();
+}
+
+}  // namespace
+}  // namespace ntp_snippets