LayoutTests/http/tests/priority-hints/link-preload-dynamic-insertion.html

<script src=../resources/testharness.js></script>
<script src=../resources/testharnessreport.js></script>
<script src="http://127.0.0.1:8000/resources/checkResourcePriority.js"></script>

<script>
  const tests = [
    // rel=style
    {
      description: 'low fetchPriority on <link rel=preload as=style> not loaded by the preload scanner must be fetched with medium resource load priority',
      as: 'style',
      fetchPriority: 'low',
      resource: 'dummy.css',
      expected_priority: "ResourceLoadPriorityMedium"
    },
    {
      description: 'missing fetchPriority on <link rel=preload as=style> not loaded by the preload scanner must be fetched with high resource load priority',
      as: 'style',
      resource: 'dummy.css',
      expected_priority: "ResourceLoadPriorityHigh"
    },
    {
      description: 'high fetchPriority on <link rel=preload as=style> not loaded by the preload scanner must be fetched with very high resource load priority',
      as: 'style',
      fetchPriority: 'high',
      resource: 'dummy.css',
      expected_priority: "ResourceLoadPriorityVeryHigh"
    },
    // rel=script
    {
      description: 'low fetchPriority on <link rel=preload as=script> not loaded by the preload scanner must be fetched with medium resource load priority',
      as: 'script',
      fetchPriority: 'low',
      resource: 'dummy.js',
      expected_priority: "ResourceLoadPriorityMedium"
    },
    {
      description: 'missing fetchPriority on <link rel=preload as=script> not loaded by the preload scanner must be fetched with high resource load priority',
      as: 'script',
      resource: 'dummy.js',
      expected_priority: "ResourceLoadPriorityHigh"
    },
    {
      description: 'high fetchPriority on <link rel=preload as=script> not loaded by the preload scanner must be fetched with very high resource load priority',
      as: 'script',
      fetchPriority: 'high',
      resource: 'dummy.js',
      expected_priority: "ResourceLoadPriorityVeryHigh"
    },
    // rel=fetch
    {
      description: 'low fetchPriority on <link rel=preload as=fetch> not loaded by the preload scanner must be fetched with low resource load priority',
      as: 'fetch',
      fetchPriority: 'low',
      resource: 'dummy.css',
      expected_priority: "ResourceLoadPriorityLow"
    },
    {
      description: 'missing fetchPriority on <link rel=preload as=fetch> not loaded by the preload scanner must be fetched with medium resource load priority',
      as: 'fetch',
      resource: 'dummy.css',
      expected_priority: "ResourceLoadPriorityMedium"
    },
    {
      description: 'high fetchPriority on <link rel=preload as=fetch> not loaded by the preload scanner must be fetched with high resource load priority',
      as: 'fetch',
      fetchPriority: 'high',
      resource: 'dummy.css',
      expected_priority: "ResourceLoadPriorityHigh"
    },
    // rel=image
    {
      description: 'low fetchPriority on <link rel=preload as=image> not loaded by the preload scanner must be fetched with very low resource load priority',
      as: 'image',
      fetchPriority: 'low',
      resource: 'square100.png',
      expected_priority: "ResourceLoadPriorityVeryLow"
    },
    {
      description: 'missing fetchPriority on <link rel=preload as=image> not loaded by the preload scanner must be fetched with low resource load priority',
      as: 'image',
      resource: 'square100.png',
      expected_priority: "ResourceLoadPriorityLow"
    },
    {
      description: 'high fetchPriority on <link rel=preload as=image> not loaded by the preload scanner must be fetched with medium resource load priority',
      as: 'image',
      fetchPriority: 'high',
      resource: 'square100.png',
      expected_priority: "ResourceLoadPriorityMedium"
    }
  ];

  let iteration = 0;
  for (const test of tests) {
    async_test(t => {
      const link = document.createElement('link');
      link.rel = 'preload';
      link.as = test.as;
      if (test.fetchPriority) link.fetchPriority = test.fetchPriority;

      const url = new URL(`../resources/${test.resource}?lpdi${iteration++}`, location);
      link.href = url;
      link.onload = t.step_func(() => { checkResourcePriority(url, test.expected_priority, test.description); t.done(); });
      document.head.appendChild(link);
    });
  }
</script>