reporting/reporting-api-orders-reports-buffered.https.html

<!DOCTYPE HTML>
<html>
<head>
  <meta charset="utf-8">
  <title>
    Reporting API: buffered observer preserves ordering across report types
  </title>
  <script src="/resources/testharness.js"></script>
  <script src="/resources/testharnessreport.js"></script>
  <script src="/resources/testdriver.js"></script>
  <script src="/resources/testdriver-vendor.js"></script>
</head>

<body>
<script>
promise_test(async t => {
  assert_true("ReportingObserver" in self);

  function generateTest(i) {
    test_driver.generate_test_report(`Test report ${i}`);
  }

  function generateDeprecation(i) {
    let img = document.createElement("img");

    img.src = `/some/bunk/file${i}.png`;
    document.body.appendChild(img);
  }

  let nonBufferedReports = [];
  const observeTwoReports = async () => {
    let { promise, resolve } = Promise.withResolvers();
    let count = 0;
    let reportingObserver = new ReportingObserver(reports => {
      count += reports.length;
      nonBufferedReports.push(...reports);
      if (count >= 2) {
        resolve();
      }
    });

    reportingObserver.observe();
    return promise.finally(() => reportingObserver.disconnect());
  }

  // Generate interleaved reports
  for (let i = 0; i < 25; i++) {
    generateTest(i);
    generateDeprecation(i);
    await observeTwoReports();
  }

  const collected = [];
  const { promise: collectedAll, resolve } = Promise.withResolvers();

  const observer = new ReportingObserver(
    reports => {
      collected.push(...reports);
      if (collected.length == nonBufferedReports.length) {
        resolve();
      }
    },
    { buffered: true }
  );

  observer.observe();

  await collectedAll;
  observer.disconnect();

  assert_greater_than(
    collected.length,
    0,
    "Some reports must be delivered"
  );

  // Verify relative ordering by type
  const observedTypes = collected.map(r => r.type);

  assert_array_equals(observedTypes, nonBufferedReports.map(r => r.type));
}, "Buffered ReportingObserver preserves report generation order");
</script>
</body>
</html>