def test_call(mock_sub, capsys):
    'A simple call to check_output will be invoked.'
    output = mock_sub.parse_output(splitlines_parser, ['hello', 'world'])
    mock_sub._subprocess.check_output.assert_called_with(['hello', 'world'], text=True)
    assert (capsys.readouterr().out == '')
    assert (output == ['some output line 1', 'more output line 2'])
A simple call to check_output will be invoked.
def test_call(mock_sub, capsys):
    
    output = mock_sub.parse_output(splitlines_parser, ['hello', 'world'])
    mock_sub._subprocess.check_output.assert_called_with(['hello', 'world'], text=True)
    assert (capsys.readouterr().out == )
    assert (output == ['some output line 1', 'more output line 2'])