def test_existing_extension_valid(self):
    ext = 'file.puk'
    expected = 'puk'
    got = get_extension(ext)
    assert (expected == got)
def test_existing_extension_valid(self):
    ext = 'file.puk'
    expected = 'puk'
    got = get_extension(ext)
    assert (expected == got)