from matplotlib.sankey import Sankey


def test_sankey():
    # lets just create a sankey instance and check the code runs
    sankey = Sankey()
    sankey.add()


def test_label():
    s = Sankey(flows=[0.25], labels=['First'], orientations=[-1])
    assert s.diagrams[0].texts[0].get_text() == 'First\n0.25'


def test_format_using_callable():
    # test using callable by slightly incrementing above label example

    def show_three_decimal_places(value):
        return f'{value:.3f}'

    s = Sankey(flows=[0.25], labels=['First'], orientations=[-1],
               format=show_three_decimal_places)

    assert s.diagrams[0].texts[0].get_text() == 'First\n0.250'