def test_launch_without_function():
    """Test the various ways `Fabric.launch()` can be called."""
    # default: no launcher, single process
    fabric = Fabric()
    nothing = Mock()
    fabric.launch(nothing)
    nothing.assert_called()

    # with a launcher on the strategy
    fabric = Fabric()
    fabric._strategy._launcher = Mock()
    fabric.launch()
    fabric._strategy._launcher.launch.assert_called()
Test the various ways `Fabric.launch()` can be called.
tests/tests_fabric/test_fabric.py