[NTP Snippets] Add tests for invalid or incomplete json

components/ntp_snippets/ntp_snippets_service_unittest.cc

 // Copyright 2015 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_service.h"
 
 #include "base/json/json_reader.h"
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 44 matching lines @@
 
 std::string GetTestJson() {
   return GetTestJson(NTPSnippet::TimeToJsonString(GetDefaultCreationTime()));
 }
 
 std::string GetTestExpiredJson() {
   return GetTestJson(NTPSnippet::TimeToJsonString(GetDefaultCreationTime()),
                      NTPSnippet::TimeToJsonString(base::Time::Now()));
 }
 
+std::string GetInvalidJson() {
+  std::string json_str = GetTestJson();
+  // Make the json invalid by removing the final closing brace.
+  return json_str.substr(0, json_str.size() - 1);
+}
+
+std::string GetIncompleteJson() {
+  std::string json_str = GetTestJson();
+  // Rename the "url" entry. The result is syntactically valid json that will
+  // fail to parse as snippets.
+  size_t pos = json_str.find("\"url\"");
+  if (pos == std::string::npos) {
+    NOTREACHED();
+    return std::string();
+  }
+  json_str[pos + 1] = 'x';
+  return json_str;
+}
+
 void ParseJson(
+    bool expect_success,
     const std::string& json,
     const ntp_snippets::NTPSnippetsService::SuccessCallback& success_callback,
     const ntp_snippets::NTPSnippetsService::ErrorCallback& error_callback) {
   base::JSONReader json_reader;
   scoped_ptr<base::Value> value = json_reader.ReadToValue(json);
-  ASSERT_TRUE(value);
+  bool success = !!value;
+  EXPECT_EQ(expect_success, success);
   if (value) {
     success_callback.Run(std::move(value));
   } else {
     error_callback.Run(json_reader.GetErrorMessage());
   }
 }
 
 }  // namespace
 
 class NTPSnippetsServiceTest : public testing::Test {
@@ skipping 11 matching lines @@
   void CreateSnippetsService() {
     scoped_refptr<base::SingleThreadTaskRunner> task_runner(
         base::ThreadTaskRunnerHandle::Get());
     scoped_refptr<net::TestURLRequestContextGetter> request_context_getter =
         new net::TestURLRequestContextGetter(task_runner.get());
 
     service_.reset(new NTPSnippetsService(
         pref_service_.get(), nullptr, task_runner, std::string("fr"), nullptr,
         make_scoped_ptr(new NTPSnippetsFetcher(
             task_runner, std::move(request_context_getter), true)),
-        base::Bind(&ParseJson)));
+        base::Bind(&ParseJson, true)));
     service_->Init(true);
   }
 
  protected:
   NTPSnippetsService* service() {
     return service_.get();
   }
 
   void LoadFromJSONString(const std::string& json) {
     service_->OnSnippetsDownloaded(json);
   }
 
+  void SetExpectJsonParseSuccess(bool expect_success) {
+    service_->parse_json_callback_ = base::Bind(&ParseJson, expect_success);
+  }
+
  private:
   base::MessageLoop message_loop_;
   scoped_ptr<TestingPrefServiceSimple> pref_service_;
   scoped_ptr<NTPSnippetsService> service_;
 
   DISALLOW_COPY_AND_ASSIGN(NTPSnippetsServiceTest);
 };
 
 TEST_F(NTPSnippetsServiceTest, Loop) {
   std::string json_str(
@@ skipping 26 matching lines @@
     EXPECT_EQ(snippet.site_title(), "Site Title");
     EXPECT_EQ(snippet.favicon_url(), GURL("http://localhost/favicon"));
     EXPECT_EQ(snippet.title(), "Title");
     EXPECT_EQ(snippet.snippet(), "Snippet");
     EXPECT_EQ(snippet.salient_image_url(),
               GURL("http://localhost/salient_image"));
     EXPECT_EQ(GetDefaultCreationTime(), snippet.publish_date());
   }
 }
 
+TEST_F(NTPSnippetsServiceTest, LoadInvalidJson) {
+  SetExpectJsonParseSuccess(false);
+  LoadFromJSONString(GetInvalidJson());
+  EXPECT_EQ(service()->size(), 0u);
+}
+
+TEST_F(NTPSnippetsServiceTest, LoadInvalidJsonWithExistingSnippets) {
+  LoadFromJSONString(GetTestJson());
+  ASSERT_EQ(service()->size(), 1u);
+
+  SetExpectJsonParseSuccess(false);
+  LoadFromJSONString(GetInvalidJson());
+  // This should not have changed the existing snippets.
+  EXPECT_EQ(service()->size(), 1u);
+}
+
+TEST_F(NTPSnippetsServiceTest, LoadIncompleteJson) {
+  LoadFromJSONString(GetIncompleteJson());
+  EXPECT_EQ(service()->size(), 0u);
+}
+
+TEST_F(NTPSnippetsServiceTest, LoadIncompleteJsonWithExistingSnippets) {
+  LoadFromJSONString(GetTestJson());
+  ASSERT_EQ(service()->size(), 1u);
+
+  LoadFromJSONString(GetIncompleteJson());
+  // This should not have changed the existing snippets.
+  EXPECT_EQ(service()->size(), 1u);
+}
+
 TEST_F(NTPSnippetsServiceTest, Discard) {
   std::string json_str(
       "{ \"recos\": [ { \"contentInfo\": { \"url\" : \"http://site.com\" }}]}");
   LoadFromJSONString(json_str);
 
   ASSERT_EQ(1u, service()->size());
 
   // Discarding a non-existent snippet shouldn't do anything.
   EXPECT_FALSE(service()->DiscardSnippet(GURL("http://othersite.com")));
   EXPECT_EQ(1u, service()->size());
@@ skipping 29 matching lines @@
 }
 
 TEST_F(NTPSnippetsServiceTest, RemoveExpiredContent) {
   std::string json_str(GetTestExpiredJson());
 
   LoadFromJSONString(json_str);
   EXPECT_EQ(service()->size(), 0u);
 }
 
 }  // namespace ntp_snippets