css/css-syntax/input-preprocessing.html

<!doctype html>
<title>Input Preprocessing</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/#input-preprocessing">

<script>

function roundtripIdent(str) {
    const rule = document.styleSheets[0].cssRules[0];
    rule.selectorText = "original-ident";
    rule.selectorText = str;
    // Check for parse error.
    if(rule.selectorText == "original-ident") return "parse error";
    return rule.selectorText;
}
function testParsing(input, expected) {
    test(()=>{
        assert_equals(roundtripIdent(input), expected);
    }, `"${input}" becomes "${expected}"`);
}

/* Can't figure out how to test the newline normalization... */

/* NULL becomes FFFD */
testParsing("foo\x00", "foo\ufffd");
testParsing("f\x00oo", "f\ufffdoo");
testParsing("\x00foo", "\ufffdfoo");
testParsing("\x00", "\ufffd");
testParsing("\x00\x00\x00", "\ufffd\ufffd\ufffd");

/* surrogates become FFFD */
testParsing("foo\ud800", "foo\ufffd");
testParsing("f\ud800oo", "f\ufffdoo");
testParsing("\ud800foo", "\ufffdfoo");
testParsing("\ud800", "\ufffd");
testParsing("\ud800\ud800\ud800", "\ufffd\ufffd\ufffd");

</script>