def METHOD_NAME(self, trajectory_data):
    """Test the ``get_step_data`` method."""
    trajectory = TrajectoryData()
    trajectory.set_trajectory(**trajectory_data)
    stepid, time, cell, symbols, positions, velocities = trajectory.get_step_data(-2)
    assert stepid == trajectory_data['stepids'][-2]
    assert time == trajectory_data['times'][-2]
    np.array_equal(cell, trajectory_data['cells'][-2, :, :])
    np.array_equal(symbols, trajectory_data['symbols'])
    np.array_equal(positions, trajectory_data['positions'][-2, :, :])
    np.array_equal(velocities, trajectory_data['velocities'][-2, :, :])