Improve Steering Controller Tests

[christophfroehlich]

Yes, you're right, there are a lot of things open to test -- but right now I just wanted to provide a quick fix for the Ackermann odometry, only rudimentary tested. Maybe we should open a new issue, tagged "help wanted" for proper testing of the steering lib -- starting with tests for the integrator functions, etc. But maybe first we should check for a redesign cf. #692

ok, I'll create a new issue then.

BTW, I just added this file 'test_steering_odometry.cpp', with some hard-coded tests. Is that the way to go, or do we want to have a more advanced testing style?

Should the expectations of the FW kinematics be true for all the different kinematic configurations? Then we could change this to a parameterized test as we have with JTC

ros2_controllers/joint_trajectory_controller/test/test_trajectory_controller_utils.hpp

Lines 695 to 710 in 1d0d753

	// From the tutorial: https://www.sandordargo.com/blog/2019/04/24/parameterized-testing-with-gtest
	class TrajectoryControllerTestParameterized
	: public TrajectoryControllerTest,
	public ::testing::WithParamInterface<
	std::tuple<std::vector<std::string>, std::vector<std::string>>>
	{
	public:
	virtual void SetUp()
	{
	TrajectoryControllerTest::SetUp();
	command_interface_types_ = std::get<0>(GetParam());
	state_interface_types_ = std::get<1>(GetParam());
	}
	static void TearDownTestCase() { TrajectoryControllerTest::TearDownTestCase(); }
	};

ros2_controllers/joint_trajectory_controller/test/test_trajectory_controller.cpp

Lines 1840 to 1849 in 1d0d753

	// position controllers
	INSTANTIATE_TEST_SUITE_P(
	PositionTrajectoryControllers, TrajectoryControllerTestParameterized,
	::testing::Values(
	std::make_tuple(std::vector<std::string>({"position"}), std::vector<std::string>({"position"})),
	std::make_tuple(
	std::vector<std::string>({"position"}), std::vector<std::string>({"position", "velocity"})),
	std::make_tuple(
	std::vector<std::string>({"position"}),
	std::vector<std::string>({"position", "velocity", "acceleration"}))));

Originally posted by @christophfroehlich in #921 (comment)