GTTF: Add a basic new unit test launcher.

base/test/gtest_xml_util.h

+// Copyright 2013 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.
+
+#ifndef BASE_TEST_GTEST_XML_UTIL_H_
+#define BASE_TEST_GTEST_XML_UTIL_H_
+
+#include <vector>
+
+#include "base/compiler_specific.h"
+
+namespace base {
+
+class FilePath;
+struct TestResult;
+
+// Produces a vector of test results based on GTest output file.
+// Returns true iff the output file exists and has been successfully parsed.

[M-A Ruel, 2013/08/14 18:42:41]

One thing;
you may want to batches multiple test cases in a single process invocation.
That's what run_test_cases.py does. The reason is that for fast test cases, ones
< 10ms, the process creation and tear down will be well over the actual test
case execution time.

But on the other hand, using aggregation means that if you process the result
synchronously, the driver doesn't know the first test case result until all the
test cases passed, which may be significant for slower test cases.

So this means you want an active pipe, not really using an on-disk file.

[Paweł Hajdan Jr., 2013/08/14 18:53:40]

Totally agreed. This is what this launcher does (see kTestBatchLimit in
unit_test_launcher.cc).
Right. Yet, we still need to wait for the child process to finish (with a
timeout) before the launcher has finished.
Well, gtest has built-in file support bot not cross-platform pipe (it has a
pipe-sending listener but only for Linux). For simplicity I'm starting with a
solution that works - it can be optimized and changed later if this turns out to
be a serious problem. I'll be encouraging developer to test the new launcher and
report what they think.

One design decision I'm very consciously making in this launcher is to strongly
favor reliability and simplicity. IMHO it's a fair tradeoff here since we're
waiting for the child process anyway.

+bool ProcessGTestOutput(const base::FilePath& output_file,
+                        std::vector<TestResult>* results) WARN_UNUSED_RESULT;
+
+}  // namespace base
+
+#endif  // BASE_TEST_GTEST_XML_UTIL_H_