firefox/testing/web-platform/tests/css/css-nesting/cssom.html

<!doctype html>
<title>Simple CSSOM manipulation of subrules</title>
<link rel="author" title="Steinar H. Gunderson" href="mailto:[email protected]">
<link rel="help" href="https://drafts.csswg.org/css-nesting-1/">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>

<style id="ss"></style>

<script>
  test(() => {
    assert_equals(CSSStyleRule.__proto__, CSSGroupingRule);
  }, "CSSStyleRule is a CSSGroupingRule");

  test(() => {
    let [ss] = document.styleSheets;
    assert_equals(ss.cssRules.length, 0);
    ss.insertRule('.a { color: red; }');
    assert_equals(ss.cssRules.length, 1);
    assert_equals(ss.cssRules[0].cssText, '.a { color: red; }');

    // Test inserting sub-cssRules, at various positions.
    ss.cssRules[0].insertRule('& .b { color: green; }');
    ss.cssRules[0].insertRule('& .c { color: blue; }', 1);
    ss.cssRules[0].insertRule('& .d { color: hotpink; }', 1);
    assert_equals(ss.cssRules[0].cssText,
`.a {
  color: red;
  & .b { color: green; }
  & .d { color: hotpink; }
  & .c { color: blue; }
}`, 'inserting should work');

    // Test deleting a rule.
    ss.cssRules[0].deleteRule(1);
    assert_equals(ss.cssRules[0].cssText,
`.a {
  color: red;
  & .b { color: green; }
  & .c { color: blue; }
}`, 'deleting should work');
  });

  // Test that out-of-bounds throws exceptions and does not affect the stylesheet.
  const sampleSheetText =
`.a {
  color: red;
  & .b { color: green; }
  & .c { color: blue; }
}`;

  test(() => {
    document.getElementById('ss').innerHTML = sampleSheetText;
    let [ss] = document.styleSheets;
    assert_throws_dom('IndexSizeError', () => { ss.cssRules[0].insertRule('& .broken {}', 3); });
    assert_equals(ss.cssRules[0].cssText, sampleSheetText, 'unchanged after no-insert');
  });

  test(() => {
    document.getElementById('ss').innerHTML = sampleSheetText;
    let [ss] = document.styleSheets;
    assert_throws_dom('IndexSizeError', () => { ss.cssRules[0].insertRule('& .broken {}', -1); });
    assert_equals(ss.cssRules[0].cssText, sampleSheetText, 'unchanged after no-insert');
  });

  test(() => {
    document.getElementById('ss').innerHTML = sampleSheetText;
    let [ss] = document.styleSheets;
    assert_throws_dom('IndexSizeError', () => { ss.cssRules[0].deleteRule(5); });
    assert_equals(ss.cssRules[0].cssText, sampleSheetText, 'unchanged after no-delete');
  });

  test(() => {
    document.getElementById('ss').innerHTML = sampleSheetText;
    let [ss] = document.styleSheets;
    assert_equals(ss.cssRules[0].cssRules[2], undefined, 'subscript out-of-bounds returns undefined');
    assert_equals(ss.cssRules[0].cssRules.item(2), null, 'item() out-of-bounds returns null');
    assert_equals(ss.cssRules[0].cssText, sampleSheetText, 'unchanged after no-access');
  });

  // Test that inserting an invalid rule throws an exception.
  test(() => {
    document.getElementById('ss').innerHTML = sampleSheetText;
    let [ss] = document.styleSheets;
    let exception;
    assert_throws_dom('SyntaxError', () => { ss.cssRules[0].insertRule('% {}'); });
    assert_equals(ss.cssRules[0].cssText, sampleSheetText, 'unchanged after invalid rule');
  });

  // Test that we can get out single rule through .cssRules.
  test(() => {
    document.getElementById('ss').innerHTML = sampleSheetText;
    let [ss] = document.styleSheets;
    assert_equals(ss.cssRules[0].cssRules[1].cssText, '& .c { color: blue; }');
  });

  // Test that we can insert a @supports rule, that it serializes in the right place
  // and has the right parent. Note that the indentation is broken per-spec.
  test(() => {
    document.getElementById('ss').innerHTML = sampleSheetText;
    let [ss] = document.styleSheets;
    ss.cssRules[0].insertRule('@supports selector(&) { & div { font-size: 10px; }}', 1);
    assert_equals(ss.cssRules[0].cssText,
`.a {
  color: red;
  & .b { color: green; }
  @supports selector(&) {
  & div { font-size: 10px; }
}
  & .c { color: blue; }
}`, '@supports is added');

    assert_equals(ss.cssRules[0].cssRules[1].parentRule, ss.cssRules[0]);
    ss.cssRules[0].deleteRule(1);
    assert_equals(ss.cssRules[0].cssText, sampleSheetText);
  });

  // Nested rules are not part of declaration lists, and thus should not
  // be possible to insert with .style.
  test(() => {
    document.getElementById('ss').innerHTML = sampleSheetText;
    let [ss] = document.styleSheets;
    ss.cssRules[0].style = 'color: olivedrab; &.d { color: peru; }';
    assert_equals(ss.cssRules[0].cssText,
`.a {
  color: olivedrab;
  & .b { color: green; }
  & .c { color: blue; }
}`, 'color is changed, new rule is ignored');
  });

  test(() => {
    document.getElementById('ss').innerHTML = sampleSheetText;
    let [ss] = document.styleSheets;
    ss.cssRules[0].cssRules[0].selectorText = 'div.b .c &';  // Allowed
    ss.cssRules[0].cssRules[1].selectorText = '.c div.b &, div &';  // Allowed.
    ss.cssRules[0].insertRule('div & {}'); // Allowed.
    assert_equals(ss.cssRules[0].cssText,
`.a {
  color: red;
  div & { }
  div.b .c & { color: green; }
  .c div.b &, div & { color: blue; }
}`, 'selectorText and insertRule');
  });

  // Rules that are dropped in forgiving parsing but that contain &,
  // must still be serialized out as they were.
  test(() => {
    const text = '.a { :is(!& .foo, .b) { color: green; } }';
    document.getElementById('ss').innerHTML = text;
    let [ss] = document.styleSheets;
    assert_equals(ss.cssRules[0].cssText,
`.a {
  :is(!& .foo, .b) { color: green; }
}`, 'invalid rule containing ampersand is kept in serialization');
  });

  test((t) => {
    let main = document.createElement('main');
    main.innerHTML = `
      <style>
        .a {
          & { z-index:1; }
          & #inner1 { z-index:1; }
          .stuff, :is(&) #inner2 { z-index:1; }
        }
      </style>
      <div id="outer" class="b">
        <div id="inner1"></div>
        <div id="inner2"></div>
      </div>
    `;
    document.documentElement.append(main);
    t.add_cleanup(() => main.remove());

    assert_equals(getComputedStyle(outer).zIndex, 'auto');
    assert_equals(getComputedStyle(inner1).zIndex, 'auto');
    assert_equals(getComputedStyle(inner2).zIndex, 'auto');

    // .a => .b
    main.firstElementChild.sheet.cssRules[0].selectorText = '.b';

    assert_equals(getComputedStyle(outer).zIndex, '1');
    assert_equals(getComputedStyle(inner1).zIndex, '1');
    assert_equals(getComputedStyle(inner2).zIndex, '1');
  }, 'Mutating the selectorText of outer rule invalidates inner rules');
</script>