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diff --git a/testing/web-platform/tests/layout-instability/partially-clipped-visual-rect.html b/testing/web-platform/tests/layout-instability/partially-clipped-visual-rect.html
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+++ b/testing/web-platform/tests/layout-instability/partially-clipped-visual-rect.html
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+<!DOCTYPE html>
+<title>Layout Instability: partially clipped visual rect</title>
+<link rel="help" href="https://wicg.github.io/layout-instability/" />
+<style>
+
+body { margin: 0; }
+#clip { width: 150px; height: 600px; overflow: hidden; }
+#j { position: relative; width: 300px; height: 200px; background: blue; }
+
+</style>
+<div id='clip'><div id='j'></div></div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="resources/util.js"></script>
+<script>
+
+promise_test(async () => {
+  const watcher = new ScoreWatcher;
+
+  // Wait for the initial render to complete.
+  await waitForAnimationFrames(2);
+
+  document.querySelector("#j").style.top = "200px";
+
+  // (clipped width 150px) * (height 200 + movement 200)
+  const expectedScore = computeExpectedScore(150 * (200 + 200), 200);
+
+  await watcher.promise;
+  assert_equals(watcher.score, expectedScore);
+}, "Partially clipped visual rect.");
+
+</script>