LayoutTests/http/tests/priority-hints/image-initial-load.html

<script src=/resources/testharness.js></script>
<script src=/resources/testharnessreport.js></script>
<script src="http://127.0.0.1:8000/resources/slow-script.pl?delay=100"></script>
<script src="http://127.0.0.1:8000/resources/checkResourcePriority.js"></script>

<script>
const priority_tests = [
  {
    url: new URL('../resources/square100.png', location),
    expected_priority: "ResourceLoadPriorityMedium",
    description: 'high fetchpriority on <img> must translate to medium resource load priority'
  },
  {
    url: new URL('../resources/square100.png?1', location),
    expected_priority: "ResourceLoadPriorityVeryLow",
    description: 'low fetchpriority on <img> must translate to very low resource load priority'
  },
  {
    url: new URL('../resources/square100.png?2', location),
    expected_priority: "ResourceLoadPriorityLow",
    description: 'auto fetchpriority on <img> must translate to low resource load priority'
  },
  {
    url: new URL('../resources/square100.png?3', location),
    expected_priority: "ResourceLoadPriorityLow",
    description: 'invalid fetchpriority on <img> must translate to low resource load priority'
  },
  {
    url: new URL('../resources/square100.png?4', location),
    expected_priority: "ResourceLoadPriorityLow",
    description: 'missing fetchpriority on <img> must translate to low resource load priority'
  }
];
</script>

<img id=img1 fetchpriority=high src=../resources/square100.png alt=img>
<img id=img2 fetchpriority=low src=../resources/square100.png?1 alt=img>
<img id=img3 fetchpriority=auto src=../resources/square100.png?2 alt=img>
<img id=img4 fetchpriority=xyz src=../resources/square100.png?3 alt=img>
<img id=img5 src=../resources/square100.png?4 alt=img>

<script>
  promise_test(async (t) => {
    await new Promise(resolve => {
      addEventListener('DOMContentLoaded', resolve);
    });

    const base_msg = " was fetched by the preload scanner";
    assert_true(internals.isPreloaded(img1.src), img1.src + base_msg);
    assert_true(internals.isPreloaded(img2.src), img2.src + base_msg);
    assert_true(internals.isPreloaded(img3.src), img3.src + base_msg);
    assert_true(internals.isPreloaded(img4.src), img4.src + base_msg);
    assert_true(internals.isPreloaded(img5.src), img5.src + base_msg);
  }, 'all images must be fetched by the preload scanner');

  // Setup the tests described by |priority_tests|.
  for (const test of priority_tests) {
    async_test(t => {
      checkResourcePriority(test.url, test.expected_priority, test.description);
      t.done();
    });
  }
</script>