def METHOD_NAME(self):
    # test that scale length is at least 2
    scale = [0]
    pattern = (
        "You must input a list of scale values that has at least " "two values."
    )
    self.assertRaisesRegex(
        PlotlyError, pattern, colors.validate_scale_values, scale
    )
    # test if first and last number is 0 and 1 respectively
    scale = [0, 1.1]
    pattern = (
        "The first and last number in your scale must be 0.0 and "
        "1.0 respectively."
    )
    self.assertRaisesRegex(
        PlotlyError, pattern, colors.validate_scale_values, scale
    )
    # test numbers increase
    scale = [0, 2, 1]
    pattern = (
        "'scale' must be a list that contains a strictly "
        "increasing sequence of numbers."
    )
    self.assertRaisesRegex(
        PlotlyError, pattern, colors.validate_scale_values, scale
    )