servo/tests/wpt/web-platform-tests/fetch/api/basic/request-referrer.js

if (this.document === undefined) {
  importScripts("/resources/testharness.js");
  importScripts("../resources/utils.js");
}

function testReferrer(referrer, expected) {
  promise_test(function(test) {
    var url = RESOURCES_DIR + "inspect-headers.py?headers=referer"
    var req = new Request(url, { referrer: referrer });
    return fetch(req).then(function(resp) {
      var actual = resp.headers.get("x-request-referer");
      if (expected) {
        assert_equals(actual, expected, "request's referer should be: " + expected);
        return;
      }
      if (actual) {
        assert_equals(actual, "", "request's referer should be empty");
      }
    });
  });
}

testReferrer("about:client", window.location.href);

var fooURL = new URL("./foo", window.location).href;
testReferrer(fooURL, fooURL);

done();