Add a unit test for JsonPrefStore::Remove.

base/prefs/json_pref_store_unittest.cc

 // Copyright (c) 2012 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 "base/prefs/json_pref_store.h"
 
 #include "base/file_util.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 239 matching lines @@
   ASSERT_FALSE(pref_store->ReadOnly());
 
   // Check values.
   const Value* result = NULL;
   EXPECT_TRUE(pref_store->GetValue("list", &result));
   EXPECT_TRUE(ListValue().Equals(result));
   EXPECT_TRUE(pref_store->GetValue("dict", &result));
   EXPECT_TRUE(DictionaryValue().Equals(result));
 }
 
+TEST_F(JsonPrefStoreTest, Remove) {
+  ASSERT_TRUE(base::CopyFile(data_dir_.AppendASCII("remove.original.json"),
+                             temp_dir_.path().AppendASCII("remove.json")));
+  base::FilePath input_output_file =
+      temp_dir_.path().AppendASCII("remove.json");
+  ASSERT_TRUE(PathExists(input_output_file));
+  scoped_refptr<JsonPrefStore> pref_store = new JsonPrefStore(
+      input_output_file,
+      message_loop_.message_loop_proxy().get(),
+      scoped_ptr<PrefFilter>());
+  ASSERT_EQ(PersistentPrefStore::PREF_READ_ERROR_NONE, pref_store->ReadPrefs());
+  ASSERT_FALSE(pref_store->ReadOnly());

[Mattias Nissler (ping if slow), 2014/01/23 09:07:54]

Reading this code, I have no idea what the test is supposed to test, can you
improve that?

This would be much clearer if you just constructed the input data
programmatically instead of separating it out into a file and reading it from
there. Another option could be to put a comment here that puts the reader on the
right track.

+
+  pref_store->RemoveValue("long_int.pref");
+
+  pref_store->CommitPendingWrite();
+  RunLoop().RunUntilIdle();
+
+  base::FilePath golden_output_file =
+      data_dir_.AppendASCII("remove.golden.json");
+  EXPECT_TRUE(TextContentsEqual(golden_output_file, input_output_file));
+}
+
 // Tests asynchronous reading of the file when there is no file.
 TEST_F(JsonPrefStoreTest, AsyncNonExistingFile) {
   base::FilePath bogus_input_file = data_dir_.AppendASCII("read.txt");
   ASSERT_FALSE(PathExists(bogus_input_file));
   scoped_refptr<JsonPrefStore> pref_store = new JsonPrefStore(
       bogus_input_file,
       message_loop_.message_loop_proxy().get(),
       scoped_ptr<PrefFilter>());
   MockPrefStoreObserver mock_observer;
   pref_store->AddObserver(&mock_observer);
 
   MockReadErrorDelegate *mock_error_delegate = new MockReadErrorDelegate;
   pref_store->ReadPrefsAsync(mock_error_delegate);
 
   EXPECT_CALL(mock_observer, OnInitializationCompleted(true)).Times(1);
   EXPECT_CALL(*mock_error_delegate,
               OnError(PersistentPrefStore::PREF_READ_ERROR_NO_FILE)).Times(1);
   RunLoop().RunUntilIdle();
   pref_store->RemoveObserver(&mock_observer);
 
   EXPECT_FALSE(pref_store->ReadOnly());
 }
 
 }  // namespace base