chromium/third_party/blink/web_tests/http/tests/cache/subresource-failover-to-network.html

<body>
<script>
  if ("testRunner" in window) {
    testRunner.dumpAsText();

    document.cookie = "result=FAIL"

    // The results of the form submission is a page that performs a non-
    // cacheable sync XHR request.  Upon returning to that page, we expect the
    // sync XHR request to still succeed.  This relies on it loading from the
    // network and not being restricted to loading from the cache (as the main
    // page is).
    testRunner.queueLoadingScript("document.forms[0].submit()");
    testRunner.queueBackNavigation(1);
    testRunner.queueForwardNavigation(1);
  }
</script>
<form method="POST" action="resources/subresource-failover-to-network.cgi" enctype="multipart/form-data">
  <input type="submit">
</form>
<p>
This test verifies that a synchronous XMLHttpRequest, generated from a page
that is the result of a form submission, loads properly when the user navigates
back to the page.
<p>
When navigating back to a page that resulted from a form submission, the page
is loaded with the ReturnCacheDataDontLoad cache policy.  It is important that
subresources (including XMLHttpRequest instances) do not inherit this cache
policy.
</body>