paint-timing/first-paint-bg-color.html

<!DOCTYPE html>
<head>
<title>Performance Paint Timing Test: FP due to background color</title>
</head>
<body>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<div id="main"></div>
</body>

<footer>
<script>
async_test(function (t) {
    document.body.style.backgroundColor = "#AA0000";

    function testPaintEntries() {
      const bufferedEntries = performance.getEntriesByType('paint');
      if (bufferedEntries.length < 1) {
        t.step_timeout(function() {
          testPaintEntries();
        }, 20);
        return;
      }
      t.step(function() {
        assert_equals(bufferedEntries.length, 1, "FP should fire for background color, not FCP");
        assert_equals(bufferedEntries[0].entryType, "paint");
        assert_equals(bufferedEntries[0].name, "first-paint");
        t.done();
      });
    }
    t.step(function() {
      testPaintEntries();
    })
}, "First paint fires due to background color. No FCP");
</script>
<footer>
</html>