chromium/third_party/blink/web_tests/http/tests/navigation/post-frames.html

<script>
  if (window.testRunner) {
      testRunner.dumpAsText();
      testRunner.dumpChildFrames();
      testRunner.waitUntilDone();
      testRunner.dumpBackForwardList();
   }
</script>  

<p>Tests that a POST request in a frame is handled correctly. If this test passes, you will see a page indicating a form was POSTed.</p>

<iframe src="resources/page-that-posts.html"></iframe>