<!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>