<title>Test same-URL navigation and its effects on history</title>
<script src=/resources/testharness.js></script>
<script src=/resources/testharnessreport.js></script>
<div id=log></div>
<iframe src=resources/a.html></iframe>
<script>
async_test((t) => {
  let state = "begin"
  self[0].frameElement.onload = t.step_func(() => {
    if(state === "b first") {
      assert_equals(history.length, 2)

      state = "c first"
      navigateFrameAfterDelay(t, "resources/c.html")
    } else if (state === "c first") {
      assert_equals(history.length, 3)

      state = "a second"
      history.back(2)
    } else if (state === "a second") {
      assert_equals(history.length, 3)

      state = "a third"
      navigateFrameAfterDelay(t, "resources/a.html")
    } else if (state === "a third") {
      assert_equals(history.length, 3)
      t.done()
    }
  })
  onload = t.step_func(() => {
    assert_equals(state, "begin")
    assert_equals(history.length, 1)

    state = "b first"

    navigateFrameAfterDelay(t, "resources/b.html")
  })
})

function navigateFrameAfterDelay(t, url) {
  // Delay to avoid triggering the "replace" behavior which occurs if
  // the page isn't yet completely loaded, which only occurs after the
  // load event handlers have finished:
  // https://html.spec.whatwg.org/#location-object-navigate
  // https://html.spec.whatwg.org/#the-end:completely-finish-loading
  t.step_timeout(() => {
    self[0].location = url
  }, 0)
}
</script>
