Fake Test Node

What this package provides

When writing an integration test for a node in C++ using GTest, there is quite some boilerplate code that needs to be written to set up a fake node that would publish expected messages on an expected topic and subscribes to messages on some other topic. This is usually implemented as a custom GTest fixture.

This package contains a library that introduces two utility classes that can be used in place of custom fixtures described above to write integration tests for a node:

• autoware::fake_test_node::FakeTestNode - to use as a custom test fixture with TEST_F tests
• autoware::fake_test_node::FakeTestNodeParametrized - to use a custom test fixture with the parametrized TEST_P tests (accepts a template parameter that gets forwarded to testing::TestWithParam<T>)

These fixtures take care of initializing and re-initializing rclcpp as well as of checking that all subscribers and publishers have a match, thus reducing the amount of boilerplate code that the user needs to write.

How to use this library

After including the relevant header the user can use a typedef to use a custom fixture name and use the provided classes as fixtures in TEST_F and TEST_P tests directly.

Example usage

Let's say there is a node NodeUnderTest that requires testing. It just subscribes to std_msgs::msg::Int32 messages and publishes a std_msgs::msg::Bool to indicate that the input is positive. To test such a node the following code can be used utilizing the autoware::fake_test_node::FakeTestNode:

using FakeNodeFixture = autoware::fake_test_node::FakeTestNode;

/// @test Test that we can use a non-parametrized test.
TEST_F(FakeNodeFixture, Test) {
  Int32 msg{};
  msg.data = 15;
  const auto node = std::make_shared<NodeUnderTest>();

  Bool::SharedPtr last_received_msg{};
  auto fake_odom_publisher = create_publisher<Int32>("/input_topic");
  auto result_odom_subscription = create_subscription<Bool>("/output_topic", *node,
    [&last_received_msg](const Bool::SharedPtr msg) {last_received_msg = msg;});

  const auto dt{std::chrono::milliseconds{100LL}};
  const auto max_wait_time{std::chrono::seconds{10LL}};
  auto time_passed{std::chrono::milliseconds{0LL}};
  while (!last_received_msg) {
    fake_odom_publisher->publish(msg);
    rclcpp::spin_some(node);
    rclcpp::spin_some(get_fake_node());
    std::this_thread::sleep_for(dt);
    time_passed += dt;
    if (time_passed > max_wait_time) {
      FAIL() << "Did not receive a message soon enough.";
    }
  }
  EXPECT_TRUE(last_received_msg->data);
  SUCCEED();
}

Here only the TEST_F example is shown but a TEST_P usage is very similar with a little bit more boilerplate to set up all the parameter values, see test_fake_test_node.cpp for an example usage.