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<meta charset="utf-8">
<title>CSS Images Module Level 4: parsing invalid gradients with color interpolation methods</title>
<link rel="author" title="Sam Weinig" href="mailto:weinig@apple.com">
<link rel="help" href="https://drafts.csswg.org/css-images-4/#gradients">
<link rel="help" href="https://drafts.csswg.org/css-color-4/#color-interpolation-method">
<meta name="assert" content="gradients supports the addition of color-interpolation-method to the grammar">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/css/support/parsing-testcommon.js"></script>
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<script>

function test_each_interpolation_method(gradientFunction) {
    test_invalid_value(`background-image`, `${gradientFunction}(, red, blue)`)

    for (const colorSpace of [ "lab", "oklab", "srgb", "srgb-linear", "xyz", "xyz-d50", "xyz-d65" ]) {
        const colorInterpolationMethod = colorSpace

        test_invalid_value(`background-image`, `${gradientFunction}(red, blue, ${colorInterpolationMethod})`) // interpolation method after color stops
        test_invalid_value(`background-image`, `${gradientFunction}(${colorSpace} ${colorSpace}, red, blue)`) // duplicated color space
        test_invalid_value(`background-image`, `${gradientFunction}(${colorSpace} shorter hue, red, blue)`) // invalid color space for hue modifier
    }

    for (const colorSpace of [ "hsl", "hwb", "lch", "oklch" ]) {
        test_invalid_value(`background-image`, `${gradientFunction}(${colorSpace} foo hue, red, blue)`) // invalid hue method
        test_invalid_value(`background-image`, `${gradientFunction}(${colorSpace} hue, red, blue)`) // missing interpolation method
        test_invalid_value(`background-image`, `${gradientFunction}(${colorSpace} ${colorSpace}, red, blue)`) // duplicated color space

        for (const hueInterpolationMethod of [ "shorter", "longer", "increasing", "decreasing", "specified" ]) {
            test_invalid_value(`background-image`, `${gradientFunction}(${colorSpace} ${hueInterpolationMethod}, red, blue)`) // missing 'hue' keyword
            test_invalid_value(`background-image`, `${gradientFunction}(${hueInterpolationMethod} hue ${colorSpace}, red, blue)`) // hue method before color space
            test_invalid_value(`background-image`, `${gradientFunction}(red, blue, ${colorSpace} ${hueInterpolationMethod} hue)`) // interpolation method after color stops
        }
    }
}

test_each_interpolation_method("linear-gradient")
test_each_interpolation_method("radial-gradient")
test_each_interpolation_method("conic-gradient")
</script>
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