<!DOCTYPE html>

<meta charset="utf-8">
<title>Correct events for short animations with syncbases</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<link rel="author" title="Edvard Thörnros" href="mailto:edvardt@opera.com">
<link rel="help" href="https://svgwg.org/specs/animations/#TimingAttributes">

<svg viewBox="0 0 250 50" xmlns="http://www.w3.org/2000/svg">
  <g id="a" opacity="0">
    <animate attributeName="opacity" from="0" to="1" begin="0ms;last.end+100ms" dur="10ms" fill="freeze"
      id="first"/>
    <animate attributeName="opacity" from="1" to="0" begin="last.end" dur="10ms" fill="freeze"/>
    <rect x="0" y="0" width="50" height="50" fill="#AA0"/>
  </g>
  <g id="b" opacity="0">
    <animate attributeName="opacity" from="1" to="1" begin="first.end+10ms" dur="10ms" fill="freeze"
      id="last" onend="onend_filling()"/>
    <animate attributeName="opacity" from="1" to="0" begin="last.end+1ms" dur="10ms" fill="freeze"
      onbegin="onend_clearing()"/>
    <rect x="50" y="0" width="50" height="50" fill="#AA0"/>
  </g>
</svg>
<script>
  let onend_clearing = null;
  let onend_filling = null;

  async_test(t => {
    let svg = document.querySelector("svg");
    // Deliberate no a
    let b = document.querySelector("#b");
    let passed = false;
    let triggers = 0;
    let filling_steps = 0;
    let runs = 3; // Issue 379751 broke after 2 cycles, hence this is a 3.
    onend_filling = t.step_func(() => {
      filling_steps++;
      if (filling_steps < (runs + 1)) return;
      svg.pauseAnimations();
      assert_unreached("Fired too many onend events.");
    });
    onend_clearing = t.step_func(() => {
      triggers++;
      if (triggers != runs) return;
      svg.pauseAnimations();
      // We don't check the first element, since it might have started fading in
      assert_not_equals(window.getComputedStyle(b, null).opacity, "1");
      t.done();
    });
  });
</script>