Bug 1979328 [wpt PR 53975] - :host::part() should only match with part and rule in the same tree, a=testonly

marco-c · marco-c · commit 553df817d7a6 · 2025-08-04T15:45:50.000Z
Automatic update from web-platform-tests :host::part() should only match with part and rule in the same tree Bug: 432289354 Change-Id: I2ec026f2d9718a0c021aaef6ad7aa1c7d27cc946 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6780977 Reviewed-by: Daniil Sakhapov <sakhapovchromium.org> Commit-Queue: Rune Lillesveen <futharkchromium.org> Cr-Commit-Position: refs/heads/main{#1491938} -- wpt-commits: 4e3f36bc65d9795eb0067567240f0a3f5f045f6c wpt-pr: 53975 UltraBlame original commit: af0037887105746ede10ecbe18d50fea210b0208
diff --git a/testing/web-platform/tests/css/css-shadow-parts/host-part-003.html b/testing/web-platform/tests/css/css-shadow-parts/host-part-003.html
@@ -0,0 +1,29 @@
+<!DOCTYPE html>
+<title>CSS Shadow Parts - :host::part() not matching in inner scope</title>
+<link rel="help" href="https://drafts.csswg.org/css-shadow-parts/#part">
+<link rel="help" href="https://drafts.csswg.org/css-scoping/#host-selector">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="outer">
+  <template shadowrootmode="open">
+    <style>
+      :host::part(x) {
+        color: red;
+      }
+    </style>
+    <div id="inner">
+      <template shadowrootmode="open">
+        <style>
+          p { color: green; }
+        </style>
+        <p part="x">This should not be red</p>
+      </template>
+    </div>
+  </template>
+</div>
+<script>
+  test(() => {
+    const part = outer.shadowRoot.querySelector("#inner").shadowRoot.querySelector("p");
+    assert_equals(getComputedStyle(part).color, "rgb(0, 128, 0)");
+  }, ":host::part() should only match when the part is in the same tree as the rule");
+</script>
