Blitz - WPT: CSSPseudoElement-view-transitions.tentative.html

wpt / css / css-pseudo / CSSPseudoElement-view-transitions.tentative.html

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

Subtest	Status	Message
CSSPseudoElement can represent view transition pseudo-elements	FAIL	assert_implements: Missing document.startViewTransition undefined
CSSPseudoElement hierarchy is correctly built when querying sub-pseudo-elements	FAIL	assert_implements: Missing document.startViewTransition undefined
CSSPseudoElement for view transitions is identity-consistent and can be fetched directly from originating element	FAIL	assert_implements: Missing document.startViewTransition undefined
CSSPseudoElement isolates view transitions with different names and validates them during traversal	FAIL	assert_implements: Missing document.startViewTransition undefined

Enable JavaScript in test iframe

/css/css-pseudo/CSSPseudoElement-view-transitions.tentative.html

<!DOCTYPE html>
<html>
<title>CSS Pseudo Test: CSSPseudoElement with view transitions</title>
<link rel="help" href="https://drafts.csswg.org/css-pseudo-4/#CSSPseudoElement-interface">
<link rel="help" href="https://drafts.csswg.org/css-view-transitions-1/#pseudo">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
  #target {
    width: 100px;
    height: 100px;
    background: blue;
    contain: paint;
    view-transition-name: target;
  }
  #other {
    width: 100px;
    height: 100px;
    background: green;
    contain: paint;
    view-transition-name: other;
  }
</style>
<div id="target"></div>
<div id="other"></div>
<script>
  promise_test(async t => {
    assert_implements(document.startViewTransition, "Missing document.startViewTransition");
    await new Promise(resolve => requestAnimationFrame(() => requestAnimationFrame(resolve)));
    let transition = document.startViewTransition(() => {
      document.getElementById("target").style.background = "red";
    });
    t.add_cleanup(() => transition.skipTransition());
    await transition.ready;
    let html = document.documentElement;
    let vt = html.pseudo("::view-transition");
    assert_true(vt instanceof CSSPseudoElement, "::view-transition is CSSPseudoElement");
    assert_equals(vt.type, "::view-transition");
    assert_equals(vt.parent, html);

    let group = vt.pseudo("::view-transition-group(target)");
    assert_true(group instanceof CSSPseudoElement, "::view-transition-group works via parent proxy");
    assert_equals(group.type, "::view-transition-group");
    assert_equals(group.parent, vt, "parent of group should be view-transition");

    let imagePair = group.pseudo("::view-transition-image-pair(target)");
    assert_true(imagePair instanceof CSSPseudoElement, "::view-transition-image-pair works via parent proxy");
    assert_equals(imagePair.type, "::view-transition-image-pair");
    assert_equals(imagePair.parent, group, "parent of image-pair should be group");

    let oldVT = imagePair.pseudo("::view-transition-old(target)");
    assert_true(oldVT instanceof CSSPseudoElement, "::view-transition-old works via parent proxy");
    assert_equals(oldVT.type, "::view-transition-old");
    assert_equals(oldVT.parent, imagePair, "parent of old should be image-pair");

    let newVT = imagePair.pseudo("::view-transition-new(target)");
    assert_true(newVT instanceof CSSPseudoElement, "::view-transition-new works via parent proxy");
    assert_equals(newVT.type, "::view-transition-new");
    assert_equals(newVT.parent, imagePair, "parent of new should be image-pair");
  }, "CSSPseudoElement can represent view transition pseudo-elements");

  promise_test(async t => {
    assert_implements(document.startViewTransition, "Missing document.startViewTransition");
    await new Promise(resolve => requestAnimationFrame(() => requestAnimationFrame(resolve)));
    let transition = document.startViewTransition(() => {
      document.getElementById("target").style.background = "green";
    });
    t.add_cleanup(() => transition.skipTransition());
    await transition.ready;
    let html = document.documentElement;

    let newVT = html.pseudo("::view-transition-new(target)");
    assert_true(newVT instanceof CSSPseudoElement, "Direct fetch of deep pseudo-element works");
    assert_equals(newVT.type, "::view-transition-new");

    let imagePair = newVT.parent;
    assert_true(imagePair instanceof CSSPseudoElement, "Parent is instantiated");
    assert_equals(imagePair.type, "::view-transition-image-pair");

    let group = imagePair.parent;
    assert_true(group instanceof CSSPseudoElement, "Grandparent is instantiated");
    assert_equals(group.type, "::view-transition-group");

    let vt = group.parent;
    assert_true(vt instanceof CSSPseudoElement, "Great-grandparent is instantiated");
    assert_equals(vt.type, "::view-transition");
    assert_equals(vt.parent, html, "Ultimate parent is the originating element");

    let invalidGrandchild = vt.pseudo("::view-transition-image-pair(target)");
    assert_equals(invalidGrandchild, null, "Cannot fetch a grandchild directly from a higher ancestor pseudo");

    let invalidGrandchild2 = group.pseudo("::view-transition-new(target)");
    assert_equals(invalidGrandchild2, null, "Cannot fetch a grandchild directly from an intermediate pseudo");

    let invalidChild = newVT.pseudo("::view-transition-group(target)");
    assert_equals(invalidChild, null, "Cannot fetch an ancestor from a descendant");
  }, "CSSPseudoElement hierarchy is correctly built when querying sub-pseudo-elements");

  promise_test(async t => {
    assert_implements(document.startViewTransition, "Missing document.startViewTransition");
    await new Promise(resolve => requestAnimationFrame(() => requestAnimationFrame(resolve)));
    let transition = document.startViewTransition();
    t.add_cleanup(() => transition.skipTransition());
    await transition.ready;
    let html = document.documentElement;
    const types = [
      "::view-transition",
      "::view-transition-group(root)",
      "::view-transition-image-pair(root)",
      "::view-transition-old(root)",
      "::view-transition-new(root)"
    ];

    for (const type of types) {
      let pseudo = html.pseudo(type);
      assert_true(pseudo instanceof CSSPseudoElement, `${type} fetched from html is CSSPseudoElement`);
      assert_equals(pseudo.type, type.split('(')[0], `${type} has correct type`);

      let pseudo2 = html.pseudo(type);
      assert_equals(pseudo, pseudo2, `${type} is cached on html`);
    }

    let vt = html.pseudo("::view-transition");
    let groupDirect = html.pseudo("::view-transition-group(root)");
    let groupViaProxy = vt.pseudo("::view-transition-group(root)");
    assert_equals(groupDirect, groupViaProxy, "VT pseudo elements are identity consistent regardless of fetch path");

    let imagePairDirect = html.pseudo("::view-transition-image-pair(root)");
    let imagePairViaProxy = groupDirect.pseudo("::view-transition-image-pair(root)");
    assert_equals(imagePairDirect, imagePairViaProxy, "VT pseudo elements are identity consistent regardless of fetch path");
  }, "CSSPseudoElement for view transitions is identity-consistent and can be fetched directly from originating element");

  promise_test(async t => {
    assert_implements(document.startViewTransition, "Missing document.startViewTransition");
    await new Promise(resolve => requestAnimationFrame(() => requestAnimationFrame(resolve)));
    let transition = document.startViewTransition(() => {
      document.getElementById("target").style.background = "yellow";
      document.getElementById("other").style.background = "yellow";
    });
    t.add_cleanup(() => transition.skipTransition());
    await transition.ready;
    let html = document.documentElement;

    let groupTarget = html.pseudo("::view-transition-group(target)");
    let groupOther = html.pseudo("::view-transition-group(other)");
    let groupRoot = html.pseudo("::view-transition-group(root)");

    assert_true(groupTarget instanceof CSSPseudoElement, "Target group exists");
    assert_true(groupOther instanceof CSSPseudoElement, "Other group exists");
    assert_true(groupRoot instanceof CSSPseudoElement, "Root group exists");

    assert_not_equals(groupTarget, groupRoot, "Named transitions must not match the root transition");
    assert_not_equals(groupTarget, groupOther, "Different view transition names must return different instances");

    // Cross-name query validation:
    // ::view-transition-group(target).pseudo("::view-transition-image-pair(other)") should fail
    let invalidCrossChild = groupTarget.pseudo("::view-transition-image-pair(other)");
    assert_equals(invalidCrossChild, null, "Cannot fetch a child with a mismatched view transition name from an intermediate proxy");

    // ::view-transition.pseudo("::view-transition-group(target)") should work (A(null).pseudo(B(target)))
    let vt = html.pseudo("::view-transition");
    let groupTargetViaVT = vt.pseudo("::view-transition-group(target)");
    assert_equals(groupTargetViaVT, groupTarget, "Fetching named group from root VT proxy works");
  }, "CSSPseudoElement isolates view transitions with different names and validates them during traversal");
</script>
</html>