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 "testing/gtest/include/gtest/gtest.h"
+#include "testing/platform_test.h"
+
+namespace {
+
+const FilePath::CharType kFolderPrefix[] =
+    FILE_PATH_LITERAL("TraceSubscriberStdioTest");
+
+class TraceSubscriberStdioTest : public testing::Test {
+ public:
+  virtual void SetUp() {
+    ASSERT_TRUE(file_util::CreateNewTempDirectory(kFolderPrefix, &trace_dir_));

[Paweł Hajdan Jr., 2011/05/18 20:00:46]

Oh, could you just use ScopedTempDir instead?

[lain Merrick, 2011/05/19 15:49:00]

Done.

I originally based this code on some existing tests which used FileAutoDeleter,
but then realised that's in chrome/test and we probably shouldn't include it
from content/browser. Maybe we should refactor those tests to use ScopedTempDir,
or move chrome/test/file_test_utils.h into base?

+    trace_file_ = trace_dir_.AppendASCII("trace.txt");
+  }
+  virtual void TearDown() {
+    if (!trace_dir_.empty()) {
+      file_util::Delete(trace_dir_, true);
+      trace_dir_.clear();
+    }
+  }
+  std::string ReadTraceFile() {
+    std::string result;
+    file_util::ReadFileToString(trace_file_, &result);

[Paweł Hajdan Jr., 2011/05/18 20:00:46]

How about checking the return value?

[lain Merrick, 2011/05/19 15:49:00]

Done.

+    return result;
+  }
+
+  FilePath trace_dir_;
+  FilePath trace_file_;
+};
+
+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());
+}
+
+}

[Paweł Hajdan Jr., 2011/05/18 20:00:46]

nit: Add "  // namespace"

[lain Merrick, 2011/05/19 15:49:00]

Done.