third_party/blink/web_tests/security/about-blank-include-file.html

<!--
  The about:blank iframe should be local to its initiator and inherit the
  subresources loaders. In particular, it inherits the ability to load local
  files.
-->
<script src="../resources/testharness.js"></script>
<script src="../resources/testharnessreport.js"></script>

<!-- A simple producer-consumer queue -->
<script>
  setup({single_test: true});

  let pendingReaders = [];
  let pendingMessages= [];

  let receive = function() {
    return new Promise(resolve => {
      if (pendingMessages.length != 0)
        resolve(pendingMessages.shift());
      else
        pendingReaders.push(resolve);
    });
  }

  let send = function(message) {
    if (pendingReaders.length != 0)
      pendingReaders.shift()(message);
    else
      pendingMessages.push(message)
  }
</script>

<iframe name="theiframe" onload="send('iframe-load')"
                         onerror="send('iframe-error')"
                         ></iframe>
<script>
  let iframe = document.querySelector("iframe");

  let addScript = function() {
    let iframeDocument = iframe.contentWindow.document;
    let script = iframeDocument.createElement("script");
    script.src = "./resources/script.js";
    script.onload = () => send("script-load");
    script.onerror = () => send("script-error");
    iframeDocument.body.appendChild(script);
  };

  async function test() {
    // 1. Test from the initial empty document.
    assert_equals(await receive(), "iframe-load");
    addScript();
    assert_equals(await receive(), "script-load");

    // 2. Test after a manual about:blank navigation using iframe.src.
    iframe.src = "about:blank"
    assert_equals(await receive(), "iframe-load");
    addScript();
    assert_equals(await receive(), "script-load");

    // 3. Navigate cross-process (e.g. not about:blank).
    iframe.src="http://127.0.0.1:8000/resources/dummy.html";
    assert_equals(await receive(), "iframe-load");

    // 4. Retry step 2.
    iframe.src = "about:blank"
    assert_equals(await receive(), "iframe-load");
    addScript();
    assert_equals(await receive(), "script-load", "https://crbug.com/981819.");

    done();
  };
  test();
</script>