Kill the test harness if any test exceeds a timeout. (flutter#16349)

Our tests depend on explicit latching to verify assertion are checked. If a test
does not respond for a long time, it has probably encoutered a deadlock. Instead
of waiting for the test runner to detect this, apply a very aggresive timeout on
a per test basis.

testing/BUILD.gn

@@ -28,6 +28,8 @@ source_set("testing") {
 
   sources = [
     "run_all_unittests.cc",
+    "test_timeout_listener.cc",
+    "test_timeout_listener.h",
   ]
 
   public_deps = [

testing/run_all_unittests.cc

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 #include "flutter/fml/build_config.h"
+#include "flutter/testing/test_timeout_listener.h"
 #include "gtest/gtest.h"
 
 #ifdef OS_IOS
@@ -18,5 +19,10 @@ int main(int argc, char** argv) {
 #endif  // OS_IOS
 
   ::testing::InitGoogleTest(&argc, argv);
-  return RUN_ALL_TESTS();
+  auto timeout_listener = new flutter::testing::TestTimeoutListener();
+  auto& listeners = ::testing::UnitTest::GetInstance()->listeners();
+  listeners.Append(timeout_listener);
+  auto result = RUN_ALL_TESTS();
+  delete listeners.Release(timeout_listener);
+  return result;
 }

testing/test_timeout_listener.cc

@@ -0,0 +1,121 @@
+// Copyright 2013 The Flutter 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 "flutter/testing/test_timeout_listener.h"
+
+#include <map>
+#include <sstream>
+
+namespace flutter {
+namespace testing {
+
+class PendingTests : public std::enable_shared_from_this<PendingTests> {
+ public:
+  static std::shared_ptr<PendingTests> Create(
+      fml::RefPtr<fml::TaskRunner> host_task_runner,
+      fml::TimeDelta timeout) {
+    return std::shared_ptr<PendingTests>(
+        new PendingTests(std::move(host_task_runner), timeout));
+  }
+
+  ~PendingTests() = default;
+
+  void OnTestBegin(const std::string& test_name, fml::TimePoint test_time) {
+    FML_CHECK(tests_.find(test_name) == tests_.end())
+        << "Attempting to start a test that is already pending.";
+    tests_[test_name] = test_time;
+
+    host_task_runner_->PostDelayedTask(
+        [weak = weak_from_this()] {
+          if (auto strong = weak.lock()) {
+            strong->CheckTimedOutTests();
+          }
+        },
+        timeout_);
+  }
+
+  void OnTestEnd(const std::string& test_name) { tests_.erase(test_name); }
+
+  void CheckTimedOutTests() const {
+    const auto now = fml::TimePoint::Now();
+
+    for (const auto& test : tests_) {
+      auto delay = now - test.second;
+      FML_CHECK(delay < timeout_)
+          << "Test " << test.first << " did not complete in "
+          << timeout_.ToSeconds()
+          << " seconds and is assumed to be hung. Killing the test harness.";
+    }
+  }
+
+ private:
+  using TestData = std::map<std::string, fml::TimePoint>;
+
+  fml::RefPtr<fml::TaskRunner> host_task_runner_;
+  TestData tests_;
+  const fml::TimeDelta timeout_;
+
+  PendingTests(fml::RefPtr<fml::TaskRunner> host_task_runner,
+               fml::TimeDelta timeout)
+      : host_task_runner_(std::move(host_task_runner)), timeout_(timeout) {}
+
+  FML_DISALLOW_COPY_AND_ASSIGN(PendingTests);
+};
+
+template <class T>
+auto WeakPtr(std::shared_ptr<T> pointer) {
+  return std::weak_ptr<T>{pointer};
+}
+
+TestTimeoutListener::TestTimeoutListener(fml::TimeDelta timeout)
+    : timeout_(timeout),
+      listener_thread_("test_timeout_listener"),
+      listener_thread_runner_(listener_thread_.GetTaskRunner()),
+      pending_tests_(PendingTests::Create(listener_thread_runner_, timeout_)) {}
+
+TestTimeoutListener::~TestTimeoutListener() {
+  listener_thread_runner_->PostTask(
+      [tests = std::move(pending_tests_)]() mutable { tests.reset(); });
+  FML_CHECK(pending_tests_ == nullptr);
+}
+
+static std::string GetTestNameFromTestInfo(
+    const ::testing::TestInfo& test_info) {
+  std::stringstream stream;
+  stream << test_info.test_suite_name();
+  stream << ".";
+  stream << test_info.name();
+  if (auto type_param = test_info.type_param()) {
+    stream << "/" << type_param;
+  }
+  if (auto value_param = test_info.value_param()) {
+    stream << "/" << value_param;
+  }
+  return stream.str();
+}
+
+// |testing::EmptyTestEventListener|
+void TestTimeoutListener::OnTestStart(const ::testing::TestInfo& test_info) {
+  listener_thread_runner_->PostTask([weak_tests = WeakPtr(pending_tests_),
+                                     name = GetTestNameFromTestInfo(test_info),
+                                     now = fml::TimePoint::Now()]() {
+    if (auto tests = weak_tests.lock()) {
+      tests->OnTestBegin(std::move(name), now);
+    }
+  });
+}
+
+// |testing::EmptyTestEventListener|
+void TestTimeoutListener::OnTestEnd(const ::testing::TestInfo& test_info) {
+  listener_thread_runner_->PostTask(
+      [weak_tests = WeakPtr(pending_tests_),
+       name = GetTestNameFromTestInfo(test_info)]() {
+        if (auto tests = weak_tests.lock()) {
+          tests->OnTestEnd(std::move(name));
+        }
+      });
+}
+
+}  // namespace testing
+}  // namespace flutter

testing/test_timeout_listener.h

@@ -0,0 +1,45 @@
+// Copyright 2013 The Flutter 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 FLUTTER_TESTING_TEST_TIMEOUT_LISTENER_H_
+#define FLUTTER_TESTING_TEST_TIMEOUT_LISTENER_H_
+
+#include <memory>
+
+#include "flutter/fml/macros.h"
+#include "flutter/fml/task_runner.h"
+#include "flutter/fml/thread.h"
+#include "flutter/testing/testing.h"
+
+namespace flutter {
+namespace testing {
+
+class PendingTests;
+
+class TestTimeoutListener : public ::testing::EmptyTestEventListener {
+ public:
+  TestTimeoutListener(
+      fml::TimeDelta timeout = fml::TimeDelta::FromSeconds(30u));
+
+  ~TestTimeoutListener();
+
+ private:
+  const fml::TimeDelta timeout_;
+  fml::Thread listener_thread_;
+  fml::RefPtr<fml::TaskRunner> listener_thread_runner_;
+  std::shared_ptr<PendingTests> pending_tests_;
+
+  // |testing::EmptyTestEventListener|
+  void OnTestStart(const ::testing::TestInfo& test_info) override;
+
+  // |testing::EmptyTestEventListener|
+  void OnTestEnd(const ::testing::TestInfo& test_info) override;
+
+  FML_DISALLOW_COPY_AND_ASSIGN(TestTimeoutListener);
+};
+
+}  // namespace testing
+}  // namespace flutter
+
+#endif  // FLUTTER_TESTING_TEST_TIMEOUT_LISTENER_H_