Blitz - WPT: supports-import-parsing.html

wpt / css / css-cascade / parsing / supports-import-parsing.html

Data from commit:
a50cb89 wpt: run reference-named files which are themselves tests (#836) (2026-09-03)

Subtest	Status	Message
@import url("nonexist.css") supports(); should be an invalid import rule due to an invalid supports() declaration	FAIL	Cannot destructure 'undefined' value
@import url("nonexist.css") supports(foo: bar); should be an invalid import rule due to an invalid supports() declaration	FAIL	Cannot destructure 'undefined' value
@import url("nonexist.css") supports(display:block); should be a valid supports() import rule	FAIL	Cannot destructure 'undefined' value
@import url("nonexist.css") supports((display:flex)); should be a valid supports() import rule	FAIL	Cannot destructure 'undefined' value
@import url("nonexist.css") supports(not (display: flex)); should be a valid supports() import rule	FAIL	Cannot destructure 'undefined' value
@import url("nonexist.css") supports((display: flex) and (display: block)); should be a valid supports() import rule	FAIL	Cannot destructure 'undefined' value
@import url("nonexist.css") supports((display: flex) or (display: block)); should be a valid supports() import rule	FAIL	Cannot destructure 'undefined' value
@import url("nonexist.css") supports((display: flex) or (foo: bar)); should be a valid supports() import rule	FAIL	Cannot destructure 'undefined' value
@import url("nonexist.css") supports(display: block !important); should be a valid supports() import rule	FAIL	Cannot destructure 'undefined' value
@import url("nonexist.css") layer supports(); should be an invalid import rule due to an invalid supports() declaration	FAIL	Cannot destructure 'undefined' value
@import url("nonexist.css") layer supports(foo: bar); should be an invalid import rule due to an invalid supports() declaration	FAIL	Cannot destructure 'undefined' value
@import url("nonexist.css") layer(A) supports((display: flex) or (foo: bar)); should be a valid supports() import rule	FAIL	Cannot destructure 'undefined' value
@import url("nonexist.css") layer(A.B) supports((display: flex) and (foo: bar)); should be a valid supports() import rule	FAIL	Cannot destructure 'undefined' value
@import url("nonexist.css") supports(selector(a)); should be a valid supports() import rule	FAIL	Cannot destructure 'undefined' value
@import url("nonexist.css") supports(selector(p a)); should be a valid supports() import rule	FAIL	Cannot destructure 'undefined' value
@import url("nonexist.css") supports(selector(p > a)); should be a valid supports() import rule	FAIL	Cannot destructure 'undefined' value
@import url("nonexist.css") supports(selector(p + a)); should be a valid supports() import rule	FAIL	Cannot destructure 'undefined' value
@import url("nonexist.css") supports(font-tech(color-colrv1)); should be a valid supports() import rule	FAIL	Cannot destructure 'undefined' value
@import url("nonexist.css") supports(font-format(opentype)); should be a valid supports() import rule	FAIL	Cannot destructure 'undefined' value
@import url(nonexist.css) supports(display:block); should be a valid supports() import rule	FAIL	Cannot destructure 'undefined' value
@import "nonexist.css" supports(display:block); should be a valid supports() import rule	FAIL	Cannot destructure 'undefined' value
@import url("nonexist.css") supports; should still be a valid import rule with an invalid supports() declaration	FAIL	Cannot destructure 'undefined' value

Enable JavaScript in test iframe

/css/css-cascade/parsing/supports-import-parsing.html

<!doctype html>
<meta charset="utf-8">
<title>@import rule with supports parsing / serialization</title>
<link rel="author" href="mailto:oj@oojmed.com">
<link rel="help" href="https://drafts.csswg.org/css-cascade-4/#at-import">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script>
  function setupSheet(rule) {
    const style = document.createElement("style");
    document.head.append(style);
    const {sheet} = style;
    const {cssRules} = sheet;

    assert_equals(cssRules.length, 0, "Sheet should have no rules");
    sheet.insertRule(rule);
    assert_equals(cssRules.length, 1, "Sheet should have 1 rule");

    return {sheet, cssRules};
  }

  function test_valid_supports_import(rule, serialized) {
    if (serialized === undefined)
        serialized = rule;

    test(function() {
      const {sheet, cssRules} = setupSheet(rule);

      const serialization = cssRules[0].cssText;
      assert_equals(serialization, serialized, 'serialization should be canonical');

      sheet.deleteRule(0);
      assert_equals(cssRules.length, 0, 'Sheet should have no rule');
      sheet.insertRule(serialization);
      assert_equals(cssRules.length, 1, 'Sheet should have 1 rule');

      assert_equals(cssRules[0].cssText, serialization, 'serialization should round-trip');
    }, rule + ' should be a valid supports() import rule');
  }

  function test_unsupported_supports_import(rule) {
    test(function() {
      const {sheet, cssRules} = setupSheet(rule);

      sheet.deleteRule(0);
      assert_equals(cssRules.length, 0, 'Sheet should have no rule');
    }, rule + ' should still be a valid import rule with an invalid supports() declaration');
  }

  function test_invalid_supports_import(rule) {
    test(function() {
      const style = document.createElement("style");
      document.head.append(style);
      const {sheet} = style;
      const {cssRules} = sheet;

      assert_equals(cssRules.length, 0, "Sheet should have no rules");
    }, rule + ' should be an invalid import rule due to an invalid supports() declaration');
  }

  test_invalid_supports_import('@import url("nonexist.css") supports();');
  test_invalid_supports_import('@import url("nonexist.css") supports(foo: bar);');
  test_valid_supports_import('@import url("nonexist.css") supports(display:block);');
  test_valid_supports_import('@import url("nonexist.css") supports((display:flex));');
  test_valid_supports_import('@import url("nonexist.css") supports(not (display: flex));');
  test_valid_supports_import('@import url("nonexist.css") supports((display: flex) and (display: block));');
  test_valid_supports_import('@import url("nonexist.css") supports((display: flex) or (display: block));');
  test_valid_supports_import('@import url("nonexist.css") supports((display: flex) or (foo: bar));');
  test_valid_supports_import('@import url("nonexist.css") supports(display: block !important);');

  test_invalid_supports_import('@import url("nonexist.css") layer supports();');
  test_invalid_supports_import('@import url("nonexist.css") layer supports(foo: bar);');
  test_valid_supports_import('@import url("nonexist.css") layer(A) supports((display: flex) or (foo: bar));');
  test_valid_supports_import('@import url("nonexist.css") layer(A.B) supports((display: flex) and (foo: bar));');

  test_valid_supports_import('@import url("nonexist.css") supports(selector(a));');
  test_valid_supports_import('@import url("nonexist.css") supports(selector(p a));');
  test_valid_supports_import('@import url("nonexist.css") supports(selector(p > a));');
  test_valid_supports_import('@import url("nonexist.css") supports(selector(p + a));');

  test_valid_supports_import('@import url("nonexist.css") supports(font-tech(color-colrv1));');
  test_valid_supports_import('@import url("nonexist.css") supports(font-format(opentype));');

  test_valid_supports_import('@import url(nonexist.css) supports(display:block);',
                             '@import url("nonexist.css") supports(display:block);');

  test_valid_supports_import('@import "nonexist.css" supports(display:block);',
                             '@import url("nonexist.css") supports(display:block);');

  // “supports” gets parsed as an (unsupported) media query.
  test_unsupported_supports_import('@import url("nonexist.css") supports;');
</script>