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));
 }
 
+// This test is just documenting some potentially non-obvious behavior. It
+// shouldn't be taken as normative.
+TEST_F(JsonPrefStoreTest, RemoveClearsEmptyParent) {
+  FilePath pref_file = temp_dir_.path().AppendASCII("empty_values.json");
+
+  scoped_refptr<JsonPrefStore> pref_store = new JsonPrefStore(
+      pref_file,
+      message_loop_.message_loop_proxy(),
+      scoped_ptr<PrefFilter>());
+
+  base::DictionaryValue* dict = new base::DictionaryValue;
+  dict->SetString("key", "value");
+  pref_store->SetValue("dict", dict);
+
+  pref_store->RemoveValue("dict.key");
+
+  const base::Value* retrieved_dict = NULL;
+  bool has_dict = pref_store->GetValue("dict", &retrieved_dict);
+  EXPECT_FALSE(has_dict);
+}
+
 // 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