css/css-values/attr-cycle.html

<!DOCTYPE html>
<title>CSS Values and Units Test: attr</title>
<meta name="assert" content="test attr values">
<link rel="help" href="https://drafts.csswg.org/css-values-5/#attr-notations">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>

<div id="attr"></div>
<div id="expected"></div>

<script>
  function test_attr_cycle(property, propertyValue, attrValue) {
    var elem = document.getElementById("attr");
    var expectedValue = window.getComputedStyle(elem).getPropertyValue(property);

    elem.setAttribute("data-foo", attrValue);
    elem.style.setProperty(property, propertyValue);

    test(() => {
      assert_equals(window.getComputedStyle(elem).getPropertyValue(property), expectedValue,
        "Setting property \'" + property + "\' to the value \'" + propertyValue +
        "\', where \'data-foo=" + attrValue + "\' should not change it's value.");
    });
    elem.style.setProperty(property, null);
  }

  function test_attr_no_cycle(property, propertyValue, attrValue, expectedValue) {
    var elem = document.getElementById("attr");
    elem.setAttribute("data-foo", attrValue);
    elem.style.setProperty(property, propertyValue);

    var expectedElem = document.getElementById("expected");
    expectedElem.style.setProperty(property, expectedValue);

    test(() => {
      assert_equals(window.getComputedStyle(elem).getPropertyValue(property),
        window.getComputedStyle(expectedElem).getPropertyValue(property),
        "Value \'" + propertyValue + "\', where \'data-foo=" + attrValue +
        "\' should be valid for the property \'" + property + "\'.");
    });

    elem.style.setProperty(property, null);
    expectedElem.style.setProperty(property, null);
  }

  /* Simple cycle */
  test_attr_cycle('--x', 'attr(data-foo type(<ident>))', 'attr(data-foo)');
  test_attr_cycle('--x', 'attr(data-foo type(<length>))', 'attr(data-foo type(<length>))');
  test_attr_cycle('--y', 'attr(data-foo type(*))', 'attr(data-foo type(*))');

  var attrElem = document.getElementById("attr");

  attrElem.setAttribute('data-bar', 'attr(data-foo)');
  test_attr_cycle('--y', 'attr(data-foo type(*))', 'attr(data-bar type(*))');
  attrElem.removeAttribute('data-bar');

  /* Cycle with attr() and var() */
  attrElem.style.setProperty('--x', 'attr(data-foo type(*))');
  test_attr_cycle('--y', 'attr(data-foo type(*))', 'var(--x)');
  attrElem.style.setProperty('--x', null);

  attrElem.setAttribute('data-bar', 'var(--y)');
  test_attr_cycle('--y', 'attr(data-foo type(<string>))', 'attr(data-bar type(<string>))');
  attrElem.removeAttribute('data-bar');

  attrElem.setAttribute('data-bar', 'var(--x)');
  test_attr_cycle('--x', 'attr(data-foo type(*), attr(data-bar type(*)))', 'attr(data-foo type(*))');
  attrElem.removeAttribute('data-bar');

  attrElem.style.setProperty('--x', 'attr(data-foo type(*))');
  attrElem.setAttribute('data-bar', 'var(--x)');
  test_attr_cycle('--y', 'attr(data-foo type(*))', 'attr(data-bar type(*), 11) var(--x)');
  attrElem.style.setProperty('--x', null);
  attrElem.removeAttribute('data-bar');

  /* Cycle with fallback */
  test_attr_cycle('--x', 'attr(data-foo type(<length>))', 'attr(data-foo type(<length>), 11px)');
  test_attr_cycle('--x', 'attr(data-foo type(<length>), 3px)', 'var(--x)');
  test_attr_cycle('--x', 'attr(data-foo type(<length>), 3px)', 'var(--x, 11px)');

  attrElem.style.setProperty('--y', 'attr(data-foo)');
  test_attr_no_cycle('--x', 'attr(data-foo type(<custom-ident>), 3px)', 'var(--y)', '3px');
  attrElem.style.setProperty('--y', null);

  /* Cycle within attributes, so we should fallback. */
  test_attr_no_cycle('--x', 'attr(data-foo type(<length>), 11px)', 'attr(data-foo type(<length>), 3px)', '11px');
  test_attr_no_cycle('--x', 'attr(data-foo type(<length>), 11px)', 'attr(data-foo type(<length>))', '11px');
  test_attr_no_cycle('--y', 'attr(data-foo type(*), 11px)', 'attr(data-foo type(*))', '11px');

  attrElem.setAttribute('data-bar', '11px');
  test_attr_no_cycle('--x', 'attr(data-foo type(<length>), attr(data-bar type(<length>)))', 'attr(data-foo type(*))', '11px');
  attrElem.removeAttribute('data-bar');
  attrElem.setAttribute('data-bar', 'abc');
  test_attr_no_cycle('--y', 'attr(data-foo type(*), attr(data-bar))', 'attr(data-foo type(*))', '"abc"');
  attrElem.removeAttribute('data-bar');

  attrElem.setAttribute('data-bar', 'attr(data-baz type(*), 3px)');
  attrElem.setAttribute('data-baz', 'attr(data-foo type(*), 4px)');
  test_attr_no_cycle('--y', 'attr(data-foo type(*), 1px)', 'attr(data-bar type(*), 2px)', '1px');
  attrElem.removeAttribute('data-bar');
  attrElem.removeAttribute('data-baz');

  /* Cycle with var() and fallback */
  attrElem.style.setProperty('--x', 'var(--y)');
  test_attr_cycle('--y', 'var(--x, 100)', 'var(--y)');
  attrElem.style.setProperty('--x', null);

  attrElem.setAttribute('data-bar', 'var(--y)');
  attrElem.style.setProperty('--x', 'attr(data-foo)');
  test_attr_cycle('--y', 'attr(data-foo type(*))', 'attr(data-bar type(*), 11) var(--x, 3)');
  attrElem.style.setProperty('--x', null);
  attrElem.removeAttribute('data-bar');

  /* Cycle in unused fallbacks */
  test_attr_no_cycle('--y', 'attr(data-foo type(*), var(--y))', '3', '3');
  test_attr_no_cycle('--y', 'attr(data-foo type(*), attr(data-foo))', '3', '3');

  attrElem.style.setProperty('--x', 'var(--y)');
  test_attr_no_cycle('--y', 'attr(data-foo type(*), var(--x))', '3', '3');
  attrElem.style.setProperty('--x', null);

  attrElem.setAttribute('data-bar', 'attr(data-foo type(*))');
  test_attr_no_cycle('--y', 'attr(data-foo type(*), attr(data-bar type(*)))', '3', '3');
  attrElem.removeAttribute('data-bar');

  /* Cycle in fallback */
  test_attr_cycle('--y', 'attr(data-unknown type(*), var(--y))', '3');

  /* No cycle, use raw CSS string without substitution */
  attrElem.setAttribute('data-bar', 'var(--y)');
  test_attr_no_cycle('--y', 'attr(data-foo type(<string>))', 'attr(data-bar type(<string>))', '');
  attrElem.removeAttribute('data-bar');

  attrElem.style.setProperty('--x', 'attr(data-foo)');
  attrElem.setAttribute('data-bar', 'var(--x)');
  test_attr_no_cycle('--y', 'attr(data-foo type(*))', 'attr(data-bar, 11) var(--x, 3)', '"var(--x)" "attr(data-bar, 11) var(--x, 3)"');
  attrElem.removeAttribute('data-bar');
  attrElem.style.setProperty('--x', null);

  /* Same as above, but with the custom properties swapped, so that the property
     using the raw (bare) attr() and the one using type() are resolved in the
     opposite order. The result must not depend on resolution order. */
  attrElem.style.setProperty('--y', 'attr(data-foo)');
  attrElem.setAttribute('data-bar', 'var(--y)');
  test_attr_no_cycle('--x', 'attr(data-foo type(*))', 'attr(data-bar, 11) var(--y, 3)', '"var(--y)" "attr(data-bar, 11) var(--y, 3)"');
  attrElem.removeAttribute('data-bar');
  attrElem.style.setProperty('--y', null);

  /* No cycle, wrong attr syntax in attribute */
  test_attr_no_cycle('--x', 'attr(data-foo type(*), abc)', 'attr(data-foo', 'abc');

  /* Multiple attributes cycling simultaneously in bare attr() form */
  attrElem.setAttribute('data-bar', 'attr(data-foo) attr(data-bar)');
  test_attr_no_cycle('--x', 'attr(data-foo type(*), abc)', 'attr(data-bar type(*), fallback)', 'abc');
  attrElem.removeAttribute('data-bar');

  /* Transitive cycle through var() */
  attrElem.setAttribute('data-bar', 'attr(data-foo, 10px)');
  attrElem.style.setProperty('--x', 'attr(data-bar type(<length>))');
  test_attr_cycle('width', 'attr(data-foo type(<length>))', 'var(--x)');
  attrElem.style.setProperty('--x', null);
  attrElem.removeAttribute('data-bar');

  /* No cycle, --data-foo and data-foo are distinct identifiers */
  attrElem.setAttribute('data-bar', '3');
  test_attr_no_cycle('--data-foo', 'attr(data-foo type(*))', 'attr(data-bar number)', '3');
  attrElem.setAttribute('data-bar', null);

  /* Cycle in non-custom property */
  CSS.registerProperty({
    name: '--data-baz',
    syntax: '<length>',
    inherits: false,
    initialValue: '4px',
  });
  attrElem.style.setProperty('--data-baz', '3em');
  test_attr_cycle('font-size', 'attr(data-foo type(*))', 'var(--data-baz)');
  test_attr_cycle('font-size', 'attr(unknown type(*), var(--data-baz))', '');
  attrElem.style.setProperty('--data-baz', null);

  /* No cycle in non-custom property */
  attrElem.style.setProperty('--bar', '3em');
  test_attr_no_cycle('font-size', 'attr(unknown, var(--bar))', '', '48px');
  attrElem.style.setProperty('--bar', null);

  attrElem.setAttribute('data-bar', '3');
  test_attr_no_cycle('font-size', 'attr(data-foo type(*))', 'attr(data-bar em)', '48px');
  attrElem.setAttribute('data-bar', null);

  /* Cycle in unused fallback for non-custom property */
  attrElem.style.setProperty('--data-baz', '3em');
  test_attr_no_cycle('font-size', 'attr(data-foo type(<length>), var(--data-baz))', '5px', '5px');
  attrElem.style.setProperty('--data-baz', null);
</script>