1 files changed, 33 insertions, 0 deletions
diff --git a/testing/web-platform/tests/largest-contentful-paint/loadTime-after-appendChild.html b/testing/web-platform/tests/largest-contentful-paint/loadTime-after-appendChild.html
new file mode 100644
index 0000000000..2d19e73e60
--- /dev/null
+++ b/testing/web-platform/tests/largest-contentful-paint/loadTime-after-appendChild.html
@@ -0,0 +1,33 @@
+<!DOCTYPE HTML>
+<meta charset=utf-8>
+<title>Largest Contentful Paint: delayed appended image.</title>
+<body>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="resources/largest-contentful-paint-helpers.js"></script>
+<script>
+  async_test(function (t) {
+    assert_implements(window.LargestContentfulPaint, "LargestContentfulPaint is not implemented");
+    let beforeLoad;
+    const observer = new PerformanceObserver(
+      t.step_func_done(entryList => {
+        assert_equals(entryList.getEntries().length, 1);
+        const entry = entryList.getEntries()[0];
+        const url = window.location.origin + '/images/black-rectangle.png';
+        // blue.png is 100 by 50.
+        const size = 100 * 50;
+        checkImage(entry, url, 'image_id', size, beforeLoad);
+      })
+    );
+    observer.observe({type: 'largest-contentful-paint', buffered: true});
+    const img = document.createElement('img');
+    img.src = '/images/black-rectangle.png';
+    img.id = 'image_id';
+    t.step_timeout(() => {
+      beforeLoad = performance.now();
+      document.getElementById('image_div').appendChild(img);
+    }, 200)
+  }, 'Image loadTime occurs after appendChild is called.');
+</script>
+<div id='image_div'></div>
+</body>