<!DOCTYPE html>
<title>Testing substitution of guaranteed-invalid values</title>
<link rel="help" href="https://drafts.csswg.org/css-variables/#guaranteed-invalid">
<link rel="help" href="https://drafts.csswg.org/css-variables/#cycles">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
    #target1 {
        /* Cycle */
        --var1: var(--var2);
        --var2: var(--var1);

        /* Reference to cycle */
        --var3: var(--var1);

        /* Reference to non-existent property */
        --var4: var(--noexist);
    }

    #target1parent {
        --var3: inherited;
        --var4: inherited;
    }
</style>
<div id="target1parent">
    <div id="target1"></div>
</div>
<script>
    test( function () {
        let cs = getComputedStyle(target1);
        assert_equals(cs.getPropertyValue('--var1'), '');
        assert_equals(cs.getPropertyValue('--var2'), '');
    }, 'Custom properties in a cycle become guaranteed-invalid');

    test( function () {
        let cs = getComputedStyle(target1);
        assert_equals(cs.getPropertyValue('--var3'), '');
    }, 'A custom property referencing a cycle becomes guaranteed-invalid');

    test( function () {
        let cs = getComputedStyle(target1);
        assert_equals(cs.getPropertyValue('--var4'), '');
    }, 'A custom property referencing a non-existent variable becomes guaranteed-invalid');
</script>
