Move thread from test/ to util/thread/.

util/thread/thread_test.cc

+// Copyright 2015 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "util/thread/thread.h"
+
+#include "base/basictypes.h"
+#include "gtest/gtest.h"
+#include "util/synchronization/semaphore.h"
+
+namespace crashpad {
+namespace test {
+namespace {
+
+class NoopThread : public Thread {
+ public:
+  NoopThread() {}
+  ~NoopThread() override {}
+
+ private:
+  void ThreadMain() override {}
+
+  DISALLOW_COPY_AND_ASSIGN(NoopThread);
+};
+
+class WaitThread : public Thread {
+ public:
+  explicit WaitThread(Semaphore* semaphore) : semaphore_(semaphore) {}
+  ~WaitThread() override {}
+
+ private:
+  void ThreadMain() override { semaphore_->Wait(); }
+
+  Semaphore* semaphore_;
+
+  DISALLOW_COPY_AND_ASSIGN(WaitThread);
+};
+
+class JoinAndSignalThread : public Thread {
+ public:
+  JoinAndSignalThread(Thread* thread, Semaphore* semaphore)
+      : thread_(thread), semaphore_(semaphore) {}
+  ~JoinAndSignalThread() override {}
+
+ private:
+  void ThreadMain() override {
+    thread_->Join();
+    semaphore_->Signal();
+  }
+
+  Thread* thread_;
+  Semaphore* semaphore_;
+
+  DISALLOW_COPY_AND_ASSIGN(JoinAndSignalThread);
+};
+
+TEST(ThreadTest, NoStart) {
+  NoopThread thread;
+}
+
+TEST(ThreadTest, Start) {
+  NoopThread thread;
+  thread.Start();
+  thread.Join();
+}
+
+TEST(ThreadTest, JoinBlocks) {
+  Semaphore unblock_wait_thread(0);

[scottmg, 2015/05/11 21:52:00]

`unblock_wait_thread` makes it sound like a thread on line 80. Can you call this
`unblock_wait_thread_semaphore` or `unblock_waiter`?

[erikwright (departed), 2015/05/13 15:27:49]

Done.

+  Semaphore join_completed(0);
+  WaitThread wait_thread(&unblock_wait_thread);
+  wait_thread.Start();
+  JoinAndSignalThread join_and_signal_thread(&wait_thread, &join_completed);
+  join_and_signal_thread.Start();
+  // Wait 100ms to give a broken Join implementation a chance to complete.
+  ASSERT_FALSE(join_completed.TimedWait(.1));

[scottmg, 2015/05/11 21:52:00]

I don't like this timeout too much. I think just waiting and having the test
block indefinitely would be preferable to potential flakiness on a slow bot.

[Robert Sesek, 2015/05/11 22:10:51]

+1. This will be flaky.

[erikwright (departed), 2015/05/13 15:27:49]

I think you misunderstood the purpose of this timeout. We don't expect the wait
to ever complete. But if the implementation were broken, it might. So we wait a
little bit of time to ensure that it is, in fact, blocking. While this could
possibly give false positives (if it takes more than 100ms for
JoinAndSignalThread::ThreadMain to start) it should never give a false negative.

If I remove this test I don't know of any other way to assert that Join()
actually blocks.

[scottmg, 2015/05/13 17:31:49]

I guess we would need a WFMO version to avoid the timeout. Thanks for adding the
comment.

+  unblock_wait_thread.Signal();
+  join_completed.Wait();
+  join_and_signal_thread.Join();
+}
+
+}  // namespace
+}  // namespace test
+}  // namespace crashpad