Function SRIPreloadTest

test/fixtures/wpt/resources/sriharness.js:96–157

(preload_sri_success, subresource_sri_success, name,
                        number_of_requests, destination, resource_url,
                        link_attrs, subresource_attrs)

// |number_of_requests| is used to ensure that preload requests are actually
// reused as expected.
const SRIPreloadTest = (preload_sri_success, subresource_sri_success, name,
                        number_of_requests, destination, resource_url,
                        link_attrs, subresource_attrs) => {
  const test = async_test(name);
  const link = document.createElement('link');

  // Early-fail in UAs that do not support `preload` links.
  test.step_func(() => {
    assert_true(link.relList.supports('preload'),
      "This test is automatically failing because the browser does not" +
      "support `preload` links.");
  })();

  // Build up the link.
  link.rel = 'preload';
  link.as = destination;
  link.href = resource_url;
  for (const [attr_name, attr_val] of Object.entries(link_attrs)) {
    link[attr_name] = attr_val; // This may override `rel` to modulepreload.
  }

  // Preload + subresource success and failure loading functions.
  const valid_preload_failed = test.step_func(() =>
    { assert_unreached("Valid preload fired error handler.") });
  const invalid_preload_succeeded = test.step_func(() =>
    { assert_unreached("Invalid preload load succeeded.") });
  const valid_subresource_failed = test.step_func(() =>
    { assert_unreached("Valid subresource fired error handler.") });
  const invalid_subresource_succeeded = test.step_func(() =>
    { assert_unreached("Invalid subresource load succeeded.") });
  const subresource_pass = test.step_func(() => {
    verifyNumberOfResourceTimingEntries(resource_url, number_of_requests);
    test.done();
  });
  const preload_pass = test.step_func(() => {
    const subresource_element = buildElementFromDestination(
      resource_url,
      destination,
      subresource_attrs
    );

    if (subresource_sri_success) {
      subresource_element.onload = subresource_pass;
      subresource_element.onerror = valid_subresource_failed;
    } else {
      subresource_element.onload = invalid_subresource_succeeded;
      subresource_element.onerror = subresource_pass;
    }

    document.body.append(subresource_element);
  });

  if (preload_sri_success) {
    link.onload = preload_pass;
    link.onerror = valid_preload_failed;
  } else {
    link.onload = invalid_preload_succeeded;
    link.onerror = preload_pass;