cpython/Lib/test/test_colorsys.py at 01557802cc85a45ed8782a6d89118f89ab2f97f6 · python/cpython · GitHub

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import unittest
import colorsys

def frange(start, stop, step):
    while start <= stop:
        yield start
        start += step

class ColorsysTest(unittest.TestCase):

    def assertTripleEqual(self, tr1, tr2):
        self.assertEqual(len(tr1), 3)
        self.assertEqual(len(tr2), 3)
        self.assertAlmostEqual(tr1[0], tr2[0])
        self.assertAlmostEqual(tr1[1], tr2[1])
        self.assertAlmostEqual(tr1[2], tr2[2])

    def test_hsv_roundtrip(self):
        for r in frange(0.0, 1.0, 0.2):
            for g in frange(0.0, 1.0, 0.2):
                for b in frange(0.0, 1.0, 0.2):
                    rgb = (r, g, b)
                    self.assertTripleEqual(
                        rgb,
                        colorsys.hsv_to_rgb(*colorsys.rgb_to_hsv(*rgb))
                    )

    def test_hsv_values(self):
        values = [
            # rgb, hsv
            ((0.0, 0.0, 0.0), (  0  , 0.0, 0.0)), # black
            ((0.0, 0.0, 1.0), (4./6., 1.0, 1.0)), # blue
            ((0.0, 1.0, 0.0), (2./6., 1.0, 1.0)), # green
            ((0.0, 1.0, 1.0), (3./6., 1.0, 1.0)), # cyan
            ((1.0, 0.0, 0.0), (  0  , 1.0, 1.0)), # red
            ((1.0, 0.0, 1.0), (5./6., 1.0, 1.0)), # purple
            ((1.0, 1.0, 0.0), (1./6., 1.0, 1.0)), # yellow
            ((1.0, 1.0, 1.0), (  0  , 0.0, 1.0)), # white
            ((0.5, 0.5, 0.5), (  0  , 0.0, 0.5)), # grey
        ]
        for (rgb, hsv) in values:
            self.assertTripleEqual(hsv, colorsys.rgb_to_hsv(*rgb))
            self.assertTripleEqual(rgb, colorsys.hsv_to_rgb(*hsv))

    def test_hls_roundtrip(self):
        for r in frange(0.0, 1.0, 0.2):
            for g in frange(0.0, 1.0, 0.2):
                for b in frange(0.0, 1.0, 0.2):
                    rgb = (r, g, b)
                    self.assertTripleEqual(
                        rgb,
                        colorsys.hls_to_rgb(*colorsys.rgb_to_hls(*rgb))
                    )

    def test_hls_values(self):
        values = [
            # rgb, hls
            ((0.0, 0.0, 0.0), (  0  , 0.0, 0.0)), # black
            ((0.0, 0.0, 1.0), (4./6., 0.5, 1.0)), # blue
            ((0.0, 1.0, 0.0), (2./6., 0.5, 1.0)), # green
            ((0.0, 1.0, 1.0), (3./6., 0.5, 1.0)), # cyan
            ((1.0, 0.0, 0.0), (  0  , 0.5, 1.0)), # red
            ((1.0, 0.0, 1.0), (5./6., 0.5, 1.0)), # purple
            ((1.0, 1.0, 0.0), (1./6., 0.5, 1.0)), # yellow
            ((1.0, 1.0, 1.0), (  0  , 1.0, 0.0)), # white
            ((0.5, 0.5, 0.5), (  0  , 0.5, 0.0)), # grey
        ]
        for (rgb, hls) in values:
            self.assertTripleEqual(hls, colorsys.rgb_to_hls(*rgb))
            self.assertTripleEqual(rgb, colorsys.hls_to_rgb(*hls))

    def test_hls_nearwhite(self):  # gh-106498
        values = (
            # rgb, hls: these do not work in reverse
            ((0.9999999999999999, 1, 1), (0.5, 1.0, 1.0)),
            ((1, 0.9999999999999999, 0.9999999999999999), (0.0, 1.0, 1.0)),
        )
        for rgb, hls in values:
            self.assertTripleEqual(hls, colorsys.rgb_to_hls(*rgb))
            self.assertTripleEqual((1.0, 1.0, 1.0), colorsys.hls_to_rgb(*hls))

    def test_yiq_roundtrip(self):
        for r in frange(0.0, 1.0, 0.2):
            for g in frange(0.0, 1.0, 0.2):
                for b in frange(0.0, 1.0, 0.2):
                    rgb = (r, g, b)
                    self.assertTripleEqual(
                        rgb,
                        colorsys.yiq_to_rgb(*colorsys.rgb_to_yiq(*rgb))
                    )

    def test_yiq_values(self):
        values = [
            # rgb, yiq
            ((0.0, 0.0, 0.0), (0.0, 0.0, 0.0)), # black
            ((0.0, 0.0, 1.0), (0.11, -0.3217, 0.3121)), # blue
            ((0.0, 1.0, 0.0), (0.59, -0.2773, -0.5251)), # green
            ((0.0, 1.0, 1.0), (0.7, -0.599, -0.213)), # cyan
            ((1.0, 0.0, 0.0), (0.3, 0.599, 0.213)), # red
            ((1.0, 0.0, 1.0), (0.41, 0.2773, 0.5251)), # purple
            ((1.0, 1.0, 0.0), (0.89, 0.3217, -0.3121)), # yellow
            ((1.0, 1.0, 1.0), (1.0, 0.0, 0.0)), # white
            ((0.5, 0.5, 0.5), (0.5, 0.0, 0.0)), # grey
        ]
        for (rgb, yiq) in values:
            self.assertTripleEqual(yiq, colorsys.rgb_to_yiq(*rgb))
            self.assertTripleEqual(rgb, colorsys.yiq_to_rgb(*yiq))

    def test_hsv_hue_wrapping(self):
        """Test that HSV hue values outside [0,1) are handled correctly."""
        # Test with hue values outside the normal range
        test_cases = [
            (1.0, 1.0, 1.0),   # hue = 1.0 (should wrap to 0.0)
            (1.5, 1.0, 1.0),   # hue = 1.5 (should wrap to 0.5)
            (2.0, 1.0, 1.0),   # hue = 2.0 (should wrap to 0.0)
            (-0.5, 1.0, 1.0),  # hue = -0.5 (should wrap to 0.5)
        ]

        for h, s, v in test_cases:
            # Convert to RGB and back to HSV
            rgb = colorsys.hsv_to_rgb(h, s, v)
            h_out, s_out, v_out = colorsys.rgb_to_hsv(*rgb)

            # The output hue should be in [0, 1) range
            self.assertGreaterEqual(h_out, 0.0)
            self.assertLess(h_out, 1.0)

            # The round-trip should preserve the color (within tolerance)
            self.assertTripleEqual(rgb, colorsys.hsv_to_rgb(h_out, s_out, v_out))

if __name__ == "__main__":
    unittest.main()