Allow category["suggestions"] to be absent.

components/ntp_snippets/ntp_snippets_fetcher_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/ntp_snippets_fetcher.h"
 
 #include <map>
 #include <utility>
 
 #include "base/json/json_reader.h"
@@ skipping 408 matching lines @@
   EXPECT_THAT(snippets_fetcher().last_status(), Eq("OK"));
   EXPECT_THAT(snippets_fetcher().last_json(), Eq(kJsonStr));
   EXPECT_THAT(histogram_tester().GetAllSamples(
                   "NewTabPage.Snippets.FetchHttpResponseOrErrorCode"),
               ElementsAre(base::Bucket(/*min=*/200, /*count=*/1)));
   EXPECT_THAT(histogram_tester().GetAllSamples("NewTabPage.Snippets.FetchTime"),
               ElementsAre(base::Bucket(/*min=*/kTestJsonParsingLatencyMs,
                                        /*count=*/1)));
 }
 
+TEST_F(NTPSnippetsContentSuggestionsFetcherTest, EmptyCategoryIsOK) {
+  const std::string kJsonStr =
+      "{\"categories\" : [{"
+      "  \"id\": 1,"
+      "  \"localizedTitle\": \"Articles for You\""
+      "}]}";
+  SetFakeResponse(/*data=*/kJsonStr, net::HTTP_OK,
+                  net::URLRequestStatus::SUCCESS);
+  EXPECT_CALL(mock_callback(), Run(IsEmptyArticleList()));
+  snippets_fetcher().FetchSnippetsFromHosts(test_hosts(), test_lang(),
+                                            /*count=*/1,
+                                            /*interactive_request=*/true);
+  FastForwardUntilNoTasksRemain();
+  EXPECT_THAT(snippets_fetcher().last_status(), Eq("OK"));
+  EXPECT_THAT(snippets_fetcher().last_json(), Eq(kJsonStr));
+  EXPECT_THAT(histogram_tester().GetAllSamples(
+                  "NewTabPage.Snippets.FetchHttpResponseOrErrorCode"),
+              ElementsAre(base::Bucket(/*min=*/200, /*count=*/1)));
+  EXPECT_THAT(histogram_tester().GetAllSamples("NewTabPage.Snippets.FetchTime"),
+              ElementsAre(base::Bucket(/*min=*/kTestJsonParsingLatencyMs,
+                                       /*count=*/1)));
+}
+
 TEST_F(NTPSnippetsContentSuggestionsFetcherTest, ServerCategories) {
   const std::string kJsonStr =
       "{\"categories\" : [{"
       "  \"id\": 1,"
       "  \"localizedTitle\": \"Articles for You\","
       "  \"suggestions\" : [{"
       "    \"ids\" : [\"http://localhost/foobar\"],"
       "    \"title\" : \"Foo Barred from Baz\","
       "    \"snippet\" : \"...\","
       "    \"fullPageUrl\" : \"http://localhost/foobar\","
@@ skipping 274 matching lines @@
   if (snippets) {
     // Matchers above aren't any more precise than this, so this is sufficient
     // for test-failure diagnostics.
     return os << "list with " << snippets->size() << " elements";
   } else {
     return os << "null";
   }
 }
 
 }  // namespace ntp_snippets