def test_transformer_implicit_output(tree):
"""
Ensures Transformer.implicit_output adds an output tree when needed
"""
tree.service_fragment.output = None
tree.service_fragment.children = []
Transformer.implicit_output(tree)
expected = Tree('output', [tree.service_fragment.command.child()])
assert tree.service_fragment.children[-1] == expected
def test_transformer_implicit_output_none(tree):
assert Transformer.implicit_output(tree) is None