More unittests of ntp_snippets_fetcher that depend on trial param value.

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
index a0f7893ac6e11f2f6b2eccf3c5a587b2d7a6580e..53f821ab9dfc368fbcf7e0bc61bb678bc2b3b699 100644
--- a/components/ntp_snippets/ntp_snippets_fetcher_unittest.cc
+++ b/components/ntp_snippets/ntp_snippets_fetcher_unittest.cc
@@ -4,6 +4,9 @@
 
 #include "components/ntp_snippets/ntp_snippets_fetcher.h"
 
+#include <map>
+#include <utility>
+
 #include "base/json/json_reader.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/stringprintf.h"
@@ -123,20 +126,9 @@ void ParseJsonDelayed(
       base::TimeDelta::FromMilliseconds(kTestJsonParsingLatencyMs));
 }
 
-class VariationParams {
- public:
-  VariationParams(const std::string& trial_name,
-                  const std::map<std::string, std::string>& params)
-      : field_trial_list_(new metrics::SHA1EntropyProvider("foo")) {
-    variations::AssociateVariationParams(trial_name, "Group1", params);
-    base::FieldTrialList::CreateFieldTrial(trial_name, "Group1");
-  }
-
-  ~VariationParams() { variations::testing::ClearAllVariationParams(); }
-
- private:
-  base::FieldTrialList field_trial_list_;
-};
+GURL GetFetcherUrl(const char* url_format) {
+  return GURL(base::StringPrintf(url_format, google_apis::GetAPIKey().c_str()));
+}
 
 }  // namespace
 
@@ -144,13 +136,12 @@ class NTPSnippetsFetcherTest : public testing::Test {
  public:
   NTPSnippetsFetcherTest()
       : NTPSnippetsFetcherTest(
-            GURL(base::StringPrintf(kTestChromeReaderUrlFormat,
-                                    google_apis::GetAPIKey().c_str())),
+            GetFetcherUrl(kTestChromeReaderUrlFormat),
             std::map<std::string, std::string>()) {}
 
   NTPSnippetsFetcherTest(const GURL& gurl,
                          const std::map<std::string, std::string>& params)
-      : params_(ntp_snippets::kStudyName, params),
+      : params_manager_(ntp_snippets::kStudyName, params),
         mock_task_runner_(new base::TestMockTimeTaskRunner()),
         mock_task_runner_handle_(mock_task_runner_),
         signin_client_(new TestSigninClient(nullptr)),
@@ -205,7 +196,7 @@ class NTPSnippetsFetcherTest : public testing::Test {
   }
 
  private:
-  VariationParams params_;
+  variations::testing::VariationParamsManager params_manager_;
   scoped_refptr<base::TestMockTimeTaskRunner> mock_task_runner_;
   base::ThreadTaskRunnerHandle mock_task_runner_handle_;
   FailingFakeURLFetcherFactory failing_url_fetcher_factory_;
@@ -229,10 +220,16 @@ class NTPSnippetsContentSuggestionsFetcherTest : public NTPSnippetsFetcherTest {
  public:
   NTPSnippetsContentSuggestionsFetcherTest()
       : NTPSnippetsFetcherTest(
-            GURL(base::StringPrintf(kTestChromeContentSuggestionsUrlFormat,
-                                    google_apis::GetAPIKey().c_str())),
-            std::map<std::string, std::string>{
-                {"content_suggestions_backend", kContentSuggestionsBackend}}) {}
+            GetFetcherUrl(kTestChromeContentSuggestionsUrlFormat),
+            {{"content_suggestions_backend", kContentSuggestionsBackend}}) {}
+};
+
+class NTPSnippetsFetcherHostRestrictedTest : public NTPSnippetsFetcherTest {
+ public:
+  NTPSnippetsFetcherHostRestrictedTest()
+      : NTPSnippetsFetcherTest(
+            GetFetcherUrl(kTestChromeReaderUrlFormat),
+            {{"fetching_host_restrict", "on"}}) {}
 };
 
 TEST_F(NTPSnippetsFetcherTest, BuildRequestAuthenticated) {
@@ -424,10 +421,56 @@ TEST_F(NTPSnippetsFetcherTest, ShouldFetchSuccessfullyEmptyList) {
               ElementsAre(base::Bucket(/*min=*/200, /*count=*/1)));
 }
 
-// TODO(jkrcal) Return the tests ShouldReportEmptyHostsError and
-// ShouldRestrictToHosts once we have a way to change variation parameters from
-// unittests. The tests were tailored to previous default value of the parameter
-// fetching_host_restrict, which changed now.
+TEST_F(NTPSnippetsFetcherHostRestrictedTest, ShouldReportEmptyHostsError) {
+  EXPECT_CALL(mock_callback(), Run(/*snippets=*/Not(HasValue()))).Times(1);
+  snippets_fetcher().FetchSnippetsFromHosts(/*hosts=*/std::set<std::string>(),
+                                            /*language_code=*/"en-US",
+                                            /*count=*/1);
+  FastForwardUntilNoTasksRemain();
+  EXPECT_THAT(snippets_fetcher().last_status(),
+              Eq("Cannot fetch for empty hosts list."));
+  EXPECT_THAT(snippets_fetcher().last_json(), IsEmpty());
+  EXPECT_THAT(
+      histogram_tester().GetAllSamples("NewTabPage.Snippets.FetchResult"),
+      ElementsAre(base::Bucket(/*min=*/1, /*count=*/1)));
+  EXPECT_THAT(histogram_tester().GetAllSamples(
+                  "NewTabPage.Snippets.FetchHttpResponseOrErrorCode"),
+              IsEmpty());
+  // This particular error gets triggered prior to JSON parsing and hence tests
+  // observe no fetch latency.
+  EXPECT_THAT(histogram_tester().GetAllSamples("NewTabPage.Snippets.FetchTime"),
+              ElementsAre(base::Bucket(/*min=*/0, /*count=*/1)));
+}
+
+TEST_F(NTPSnippetsFetcherHostRestrictedTest, ShouldRestrictToHosts) {
+  net::TestURLFetcherFactory test_url_fetcher_factory;
+  snippets_fetcher().FetchSnippetsFromHosts(
+      {"www.somehost1.com", "www.somehost2.com"}, test_lang(), /*count=*/17);
+  net::TestURLFetcher* fetcher = test_url_fetcher_factory.GetFetcherByID(0);
+  ASSERT_THAT(fetcher, NotNull());
+  std::unique_ptr<base::Value> value =
+      base::JSONReader::Read(fetcher->upload_data());
+  ASSERT_TRUE(value) << " failed to parse JSON: "
+                     << PrintToString(fetcher->upload_data());
+  const base::DictionaryValue* dict = nullptr;
+  ASSERT_TRUE(value->GetAsDictionary(&dict));
+  const base::DictionaryValue* local_scoring_params = nullptr;
+  ASSERT_TRUE(dict->GetDictionary("advanced_options.local_scoring_params",
+                                  &local_scoring_params));
+  const base::ListValue* content_selectors = nullptr;
+  ASSERT_TRUE(
+      local_scoring_params->GetList("content_selectors", &content_selectors));
+  ASSERT_THAT(content_selectors->GetSize(), Eq(static_cast<size_t>(2)));
+  const base::DictionaryValue* content_selector = nullptr;
+  ASSERT_TRUE(content_selectors->GetDictionary(0, &content_selector));
+  std::string content_selector_value;
+  EXPECT_TRUE(content_selector->GetString("value", &content_selector_value));
+  EXPECT_THAT(content_selector_value, Eq("www.somehost1.com"));
+  ASSERT_TRUE(content_selectors->GetDictionary(1, &content_selector));
+  EXPECT_TRUE(content_selector->GetString("value", &content_selector_value));
+  EXPECT_THAT(content_selector_value, Eq("www.somehost2.com"));
+}
+
 TEST_F(NTPSnippetsFetcherTest, ShouldReportUrlStatusError) {
   SetFakeResponse(/*data=*/std::string(), net::HTTP_NOT_FOUND,
                   net::URLRequestStatus::FAILED);