<!DOCTYPE HTML>
<html>

<head>
  <meta charset="utf-8" />
  <title>This tests transfer size of resource timing when loaded from memory cache.</title>
  <script src="/resources/testharness.js"></script>
  <script src="/resources/testharnessreport.js"></script>
  <script src="resources/entry-invariants.js"></script>
</head>

<body>
  <script>
    function getScript(url) {
      const script = document.createElement("script");
      const loaded = new Promise(resolve => {
        script.onload = script.onerror = resolve;
      });
      script.src = url;
      document.body.appendChild(script);
      return loaded;
    }
    function add_iframe(url) {
      return new Promise(function (resolve) {
        var frame = document.createElement('iframe');
        frame.src = url;
        frame.onload = function () { resolve(frame); };
        document.body.appendChild(frame);
      });
    }
    promise_test(async t => {
      // Add unique token to url so that each run the url is different to avoid
      // flakiness.
      let url = 'resources/resource_timing_test0.js?unique=' +
        Math.random().toString().substr(2);
      let frame;
      return add_iframe('resources/iframe-load-from-mem-cache-transfer-size.html')
        .then((f) => {
          frame = f;
          // Load script onto iframe in order to get it into the memory cache.
          return frame.contentWindow.getScript(url.split('/')[1])
        })
        .then(() => {
          // Verify that the transferSize in case of normal load is greater than
          // 0.
          assert_positive_(
            frame.contentWindow.performance.getEntriesByType('resource')
              .filter(e => e.name.includes(url))[0], ['transferSize']);

          // Load the same script onto the parent document. This time the script
          // is coming from memory cache.
          return getScript(url);
        })
        .then(() => {
          // Verify that the transferSize in case of memory cache load is 0.
          assert_zeroed_(
            window.performance.getEntriesByType('resource')
              .filter(e => e.name.includes(url))[0], ['transferSize']);
        });
    }, "The transferSize of resource timing entries should be 0 when resource \
    is loaded from memory cache.");
  </script>
</body>

</html>
