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<head>
<meta charset="utf-8" />
<title>Resource Timing - cached resources generate performance entries</title>
<link rel="author" title="Google" href="http://www.google.com/" />
<link rel="help"
  href="https://www.w3.org/TR/resource-timing-2/#resources-included-in-the-performanceresourcetiming-interface"/>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/entry-invariants.js"></script>
<script src="resources/resource-loaders.js"></script>
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<body>
<h1>Description</h1>
<p>This test validates that a 304 Not Modified resource appears in the
Performance Timeline.</p>
<script>
// Need to fetch the same resource twice; the first will get a 200 response but
// the second request should be cached and get a 304.
promise_test(async () => {
  performance.clearResourceTimings();

  const unique = Math.random();
  const path = `resources/fake_responses.py?tag=${unique}`;

  await load.xhr_sync(path);
  await load.xhr_sync(path, {"If-None-Match": `${unique}`});
  const entries = await new Promise(resolve => {
    const accumulator = [];
    new PerformanceObserver(entry_list => {
      entry_list.getEntries().forEach(entry => {
        accumulator.push(entry);
      });
      if (accumulator.length >= 2) {
        resolve(accumulator);
      }
    }).observe({'type': 'resource', 'buffered': true});
  });


  if (entries.length != 2) {
    throw new Error(`Expecting 2 but got ${entries.length} entries`);
  }

  assert_equals(entries[0].name, entries[1].name,
    "Both entries should have the same name");
  invariants.assert_tao_pass_no_redirect_http(entries[0]);
  invariants.assert_tao_pass_304_not_modified_http(entries[1]);
}, "304 responses should still show up in the PerformanceTimeline");
</script>
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