anb-serialization.html

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This WPT test may be referenced by the following Test IDs:
- /css/css-syntax/anb-serialization.html - WPT Dashboard Interop Dashboard

<!doctype html>

<title>An+B Serialization</title>

<script src="/resources/testharness.js"></script>

<script src="/resources/testharnessreport.js"></script>

<style>

foo { color: blue; }

</style>

<meta name="author" title="Tab Atkins-Bittner">

<link rel=help href="https://drafts.csswg.org/css-syntax/#serializing-anb">

<script>

function roundtripANB(str) {

    const rule = document.styleSheets[0].cssRules[0];

    rule.selectorText = "foo";

    rule.selectorText = `:nth-child(${str})`;

    // Check for parse error.

    if(rule.selectorText == "foo") return "parse error";

    return rule.selectorText.slice(11, -1);

function testANB(input, expected) {

    test(()=>{

        assert_equals(roundtripANB(input), expected);

    }, `"${input}" becomes "${expected}"`);

/* A is 0, or omitted */

testANB("1", "1");

testANB("+1", "1");

testANB("-1", "-1");

testANB("0n + 0", "0");

testANB("0n + 1", "1");

testANB("0n - 1", "-1");

/* A is 1 */

testANB("1n", "n");

testANB("1n - 0", "n");

testANB("1n + 1", "n+1");

testANB("1n - 1", "n-1");

/* A is -1 */

testANB("-1n", "-n");

testANB("-1n - 0", "-n");

testANB("-1n + 1", "-n+1");

testANB("-1n - 1", "-n-1");

/* A is implied via + or - */

testANB("+n+1", "n+1");

testANB("-n-1", "-n-1");

/* B is 0 */

testANB("n + 0", "n");

testANB("n - 0", "n");

/* A & B both nonzero */

testANB("2n + 2", "2n+2");

testANB("-2n - 2", "-2n-2");

</script>