Re-instate: Implement lossy pref behavior for JsonPrefStore.

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/bind.h"
 #include "base/files/file_util.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/location.h"
@@ skipping 90 matching lines @@
     ASSERT_TRUE(temp_dir_.CreateUniqueTempDir());
 
     ASSERT_TRUE(PathService::Get(base::DIR_TEST_DATA, &data_dir_));
     data_dir_ = data_dir_.AppendASCII("prefs");
     ASSERT_TRUE(PathExists(data_dir_));
   }
 
   void TearDown() override {
     // Make sure all pending tasks have been processed (e.g., deleting the
     // JsonPrefStore may post write tasks).
-    message_loop_.task_runner()->PostTask(FROM_HERE,
-                                          MessageLoop::QuitWhenIdleClosure());
-    message_loop_.Run();
+    RunLoop().RunUntilIdle();
   }
 
   // The path to temporary directory used to contain the test operations.
   base::ScopedTempDir temp_dir_;
   // The path to the directory where the test data is stored.
   base::FilePath data_dir_;
   // A message loop that we can use as the file thread message loop.
   MessageLoop message_loop_;
 
  private:
   // Ensure histograms are reset for each test.
   StatisticsRecorder statistics_recorder_;
 };
 
 // Test fallback behavior for a nonexistent file.
 TEST_F(JsonPrefStoreTest, NonExistentFile) {
-  base::FilePath bogus_input_file = data_dir_.AppendASCII("read.txt");
+  base::FilePath bogus_input_file = temp_dir_.path().AppendASCII("read.txt");
   ASSERT_FALSE(PathExists(bogus_input_file));
   scoped_refptr<JsonPrefStore> pref_store = new JsonPrefStore(
       bogus_input_file, message_loop_.task_runner(), scoped_ptr<PrefFilter>());
   EXPECT_EQ(PersistentPrefStore::PREF_READ_ERROR_NO_FILE,
             pref_store->ReadPrefs());
   EXPECT_FALSE(pref_store->ReadOnly());
 }
 
 // Test fallback behavior for a nonexistent file and alternate file.
 TEST_F(JsonPrefStoreTest, NonExistentFileAndAlternateFile) {
-  base::FilePath bogus_input_file = data_dir_.AppendASCII("read.txt");
+  base::FilePath bogus_input_file = temp_dir_.path().AppendASCII("read.txt");
   base::FilePath bogus_alternate_input_file =
-      data_dir_.AppendASCII("read_alternate.txt");
+      temp_dir_.path().AppendASCII("read_alternate.txt");
   ASSERT_FALSE(PathExists(bogus_input_file));
   ASSERT_FALSE(PathExists(bogus_alternate_input_file));
   scoped_refptr<JsonPrefStore> pref_store =
       new JsonPrefStore(bogus_input_file, bogus_alternate_input_file,
                         message_loop_.task_runner(), scoped_ptr<PrefFilter>());
   EXPECT_EQ(PersistentPrefStore::PREF_READ_ERROR_NO_FILE,
             pref_store->ReadPrefs());
   EXPECT_FALSE(pref_store->ReadOnly());
 }
 
@@ skipping 160 matching lines @@
       pref_file, message_loop_.task_runner(), scoped_ptr<PrefFilter>());
 
   // Set some keys with empty values.
   pref_store->SetValue("list", new base::ListValue,
                        WriteablePrefStore::DEFAULT_PREF_WRITE_FLAGS);
   pref_store->SetValue("dict", new base::DictionaryValue,
                        WriteablePrefStore::DEFAULT_PREF_WRITE_FLAGS);
 
   // Write to file.
   pref_store->CommitPendingWrite();
-  MessageLoop::current()->RunUntilIdle();
+  RunLoop().RunUntilIdle();
 
   // Reload.
   pref_store = new JsonPrefStore(pref_file, message_loop_.task_runner(),
                                  scoped_ptr<PrefFilter>());
   ASSERT_EQ(PersistentPrefStore::PREF_READ_ERROR_NONE, pref_store->ReadPrefs());
   ASSERT_FALSE(pref_store->ReadOnly());
 
   // Check values.
   const Value* result = NULL;
   EXPECT_TRUE(pref_store->GetValue("list", &result));
@@ skipping 18 matching lines @@
   pref_store->RemoveValue("dict.key",
                           WriteablePrefStore::DEFAULT_PREF_WRITE_FLAGS);
 
   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");
+  base::FilePath bogus_input_file = temp_dir_.path().AppendASCII("read.txt");
   ASSERT_FALSE(PathExists(bogus_input_file));
   scoped_refptr<JsonPrefStore> pref_store = new JsonPrefStore(
       bogus_input_file, message_loop_.task_runner(), 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);
@@ skipping 428 matching lines @@
   histogram.ReportOutstandingWrites();
   scoped_ptr<HistogramSamples> samples =
       histogram.GetHistogram()->SnapshotSamples();
   ASSERT_EQ(3, samples->GetCount(0));
   ASSERT_EQ(1, samples->GetCount(1));
   ASSERT_EQ(1, samples->GetCount(2));
   ASSERT_EQ(1, samples->GetCount(3));
   ASSERT_EQ(6, samples->TotalCount());
 }
 
+class JsonPrefStoreLossyWriteTest : public JsonPrefStoreTest {
+ protected:
+  void SetUp() override {
+    JsonPrefStoreTest::SetUp();
+    test_file_ = temp_dir_.path().AppendASCII("test.json");
+  }
+
+  // Creates a JsonPrefStore with the given |file_writer|.
+  scoped_refptr<JsonPrefStore> CreatePrefStore() {
+    return new JsonPrefStore(test_file_, message_loop_.task_runner(),
+                             scoped_ptr<PrefFilter>());
+  }
+
+  // Return the ImportantFileWriter for a given JsonPrefStore.
+  ImportantFileWriter* GetImportantFileWriter(
+      scoped_refptr<JsonPrefStore> pref_store) {
+    return &(pref_store->writer_);
+  }
+
+  // Get the contents of kTestFile. Pumps the message loop before returning the
+  // result.
+  std::string GetTestFileContents() {
+    RunLoop().RunUntilIdle();
+    std::string file_contents;
+    ReadFileToString(test_file_, &file_contents);
+    return file_contents;
+  }
+
+ private:
+  base::FilePath test_file_;
+};
+
+TEST_F(JsonPrefStoreLossyWriteTest, LossyWriteBasic) {
+  scoped_refptr<JsonPrefStore> pref_store = CreatePrefStore();
+  ImportantFileWriter* file_writer = GetImportantFileWriter(pref_store);
+
+  // Set a normal pref and check that it gets scheduled to be written.
+  ASSERT_FALSE(file_writer->HasPendingWrite());
+  pref_store->SetValue("normal", new base::StringValue("normal"),
+                       WriteablePrefStore::DEFAULT_PREF_WRITE_FLAGS);
+  ASSERT_TRUE(file_writer->HasPendingWrite());
+  file_writer->DoScheduledWrite();
+  ASSERT_EQ("{\"normal\":\"normal\"}", GetTestFileContents());
+  ASSERT_FALSE(file_writer->HasPendingWrite());
+
+  // Set a lossy pref and check that it is not scheduled to be written.
+  // SetValue/RemoveValue.
+  pref_store->SetValue("lossy", new base::StringValue("lossy"),
+                       WriteablePrefStore::LOSSY_PREF_WRITE_FLAG);
+  ASSERT_FALSE(file_writer->HasPendingWrite());
+  pref_store->RemoveValue("lossy", WriteablePrefStore::LOSSY_PREF_WRITE_FLAG);
+  ASSERT_FALSE(file_writer->HasPendingWrite());
+
+  // SetValueSilently/RemoveValueSilently.
+  pref_store->SetValueSilently("lossy", new base::StringValue("lossy"),
+                               WriteablePrefStore::LOSSY_PREF_WRITE_FLAG);
+  ASSERT_FALSE(file_writer->HasPendingWrite());
+  pref_store->RemoveValueSilently("lossy",
+                                  WriteablePrefStore::LOSSY_PREF_WRITE_FLAG);
+  ASSERT_FALSE(file_writer->HasPendingWrite());
+
+  // ReportValueChanged.
+  pref_store->SetValue("lossy", new base::StringValue("lossy"),
+                       WriteablePrefStore::LOSSY_PREF_WRITE_FLAG);
+  ASSERT_FALSE(file_writer->HasPendingWrite());
+  pref_store->ReportValueChanged("lossy",
+                                 WriteablePrefStore::LOSSY_PREF_WRITE_FLAG);
+  ASSERT_FALSE(file_writer->HasPendingWrite());
+
+  // Call CommitPendingWrite and check that the lossy pref and the normal pref
+  // are there with the last values set above.
+  pref_store->CommitPendingWrite();
+  ASSERT_FALSE(file_writer->HasPendingWrite());
+  ASSERT_EQ("{\"lossy\":\"lossy\",\"normal\":\"normal\"}",
+            GetTestFileContents());
+}
+
+TEST_F(JsonPrefStoreLossyWriteTest, LossyWriteMixedLossyFirst) {
+  scoped_refptr<JsonPrefStore> pref_store = CreatePrefStore();
+  ImportantFileWriter* file_writer = GetImportantFileWriter(pref_store);
+
+  // Set a lossy pref and check that it is not scheduled to be written.
+  ASSERT_FALSE(file_writer->HasPendingWrite());
+  pref_store->SetValue("lossy", new base::StringValue("lossy"),
+                       WriteablePrefStore::LOSSY_PREF_WRITE_FLAG);
+  ASSERT_FALSE(file_writer->HasPendingWrite());
+
+  // Set a normal pref and check that it is scheduled to be written.
+  pref_store->SetValue("normal", new base::StringValue("normal"),
+                       WriteablePrefStore::DEFAULT_PREF_WRITE_FLAGS);
+  ASSERT_TRUE(file_writer->HasPendingWrite());
+
+  // Call DoScheduledWrite and check both prefs get written.
+  file_writer->DoScheduledWrite();
+  ASSERT_EQ("{\"lossy\":\"lossy\",\"normal\":\"normal\"}",
+            GetTestFileContents());
+  ASSERT_FALSE(file_writer->HasPendingWrite());
+}
+
+TEST_F(JsonPrefStoreLossyWriteTest, LossyWriteMixedLossySecond) {
+  scoped_refptr<JsonPrefStore> pref_store = CreatePrefStore();
+  ImportantFileWriter* file_writer = GetImportantFileWriter(pref_store);
+
+  // Set a normal pref and check that it is scheduled to be written.
+  ASSERT_FALSE(file_writer->HasPendingWrite());
+  pref_store->SetValue("normal", new base::StringValue("normal"),
+                       WriteablePrefStore::DEFAULT_PREF_WRITE_FLAGS);
+  ASSERT_TRUE(file_writer->HasPendingWrite());
+
+  // Set a lossy pref and check that the write is still scheduled.
+  pref_store->SetValue("lossy", new base::StringValue("lossy"),
+                       WriteablePrefStore::LOSSY_PREF_WRITE_FLAG);
+  ASSERT_TRUE(file_writer->HasPendingWrite());
+
+  // Call DoScheduledWrite and check both prefs get written.
+  file_writer->DoScheduledWrite();
+  ASSERT_EQ("{\"lossy\":\"lossy\",\"normal\":\"normal\"}",
+            GetTestFileContents());
+  ASSERT_FALSE(file_writer->HasPendingWrite());
+}
+
 }  // namespace base