TraceSubscriber implementation that writes to a file.

content/browser/trace_subscriber_stdio_unittest.cc

+// Copyright (c) 2011 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 "content/browser/trace_subscriber_stdio.h"
+
+#include "base/scoped_temp_dir.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace {
+
+class TraceSubscriberStdioTest : public testing::Test {
+ public:
+  virtual void SetUp() {
+    ASSERT_TRUE(trace_dir_.CreateUniqueTempDir());
+    trace_file_ = trace_dir_.path().AppendASCII("trace.txt");
+  }
+
+  std::string ReadTraceFile() {
+    std::string result;
+    EXPECT_TRUE(file_util::ReadFileToString(trace_file_, &result));
+    return result;
+  }
+
+  ScopedTempDir trace_dir_;
+  FilePath trace_file_;
+};
+
+}  // namespace
+
+TEST_F(TraceSubscriberStdioTest, CanWriteBracketedDataToFile) {
+  TraceSubscriberStdio subscriber(trace_file_);
+  subscriber.OnTraceDataCollected("[foo]");
+  subscriber.OnTraceDataCollected("[bar]");
+  EXPECT_TRUE(subscriber.IsValid());
+
+  subscriber.OnEndTracingComplete();
+  EXPECT_FALSE(subscriber.IsValid());
+
+  EXPECT_EQ("[foo,bar,]", ReadTraceFile());
+}
+