<!doctype html>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<iframe id="i" src="/common/blank.html"></iframe>
<script>
async_test(t => {
  // Wait for after the load event so that the navigation doesn't get converted
  // into a replace navigation.
  window.onload = () => t.step_timeout(() => {
    assert_equals(navigation.entries().length, 1);
    assert_equals(i.contentWindow.navigation.entries().length, 1);
    navigation.navigate("#top");
    assert_equals(navigation.entries().length, 2);
    assert_equals(i.contentWindow.navigation.entries().length, 1);
    i.contentWindow.navigation.navigate("#1");
    assert_equals(navigation.entries().length, 2);
    assert_equals(i.contentWindow.navigation.entries().length, 2);
    assert_equals(navigation.currentEntry.index, 1);
    assert_equals(i.contentWindow.navigation.currentEntry.index, 1);
    assert_true(navigation.canGoBack);
    assert_true(i.contentWindow.navigation.canGoBack);

    // There are 2 joint session history entries containing the iframe's
    // previous key. Navigate to the nearest one (which navigates the iframe
    // but not the top window).
    i.contentWindow.navigation.back().committed.then(t.step_func_done(() => {
      assert_equals(navigation.currentEntry.index, 1);
      assert_equals(i.contentWindow.navigation.currentEntry.index, 0);
    }));
  }, 0);
}, "navigation.back() goes to the nearest back entry");
</script>
