<!DOCTYPE html>
<meta charset="UTF-8">
<title>z-index interpolation</title>
<link rel="help" href="https://www.w3.org/TR/CSS2/visuren.html#z-index">
<meta name="assert" content="z-index supports animation">

<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/css/support/interpolation-testcommon.js"></script>

<style>
body {
  margin-top: 20px;
}
.layer-reference {
  position: fixed;
  top: 0px;
  height: 100vh;
  width: 50px;
  background-color: rgba(255, 255, 255, 0.75);
  font-family: sans-serif;
  text-align: center;
  padding-top: 5px;
  border: 1px solid;
}
.parent {
  z-index: 15;
}
.target {
  position: relative;
  width: 350px;
  height: 10px;
  z-index: -2;
}
.actual {
  background-color: black;
}
.expected {
  background-color: green;
}
</style>

<body></body>

<script>
test_interpolation({
  property: 'z-index',
  from: neutralKeyframe,
  to: '5',
}, [
  {at: -0.3, expect: '-4'},
  {at: 0, expect: '-2'},
  {at: 0.3, expect: '0'},
  {at: 0.6, expect: '2'},
  {at: 1, expect: '5'},
  {at: 1.5, expect: '9'},
]);

test_no_interpolation({
  property: 'z-index',
  from: 'initial',
  to: '5',
});

// We fail to inherit correctly due to style overadjustment: crbug.com/375982
test_interpolation({
  property: 'z-index',
  from: 'inherit',
  to: '5',
}, [
  {at: -0.3, expect: '18'},
  {at: 0, expect: '15'},
  {at: 0.3, expect: '12'},
  {at: 0.6, expect: '9'},
  {at: 1, expect: '5'},
  {at: 1.5, expect: '0'},
]);

test_no_interpolation({
  property: 'z-index',
  from: 'unset',
  to: '5',
});

test_interpolation({
  property: 'z-index',
  from: '-5',
  to: '5'
}, [
  {at: -0.3, expect: '-8'},
  {at: 0, expect: '-5'},
  {at: 0.3, expect: '-2'},
  {at: 0.6, expect: '1'},
  {at: 1, expect: '5'},
  {at: 1.5, expect: '10'},
]);

test_interpolation({
  property: 'z-index',
  from: '2',
  to: '4'
}, [
  {at: -0.3, expect: '1'},
  {at: 0, expect: '2'},
  {at: 0.3, expect: '3'},
  {at: 0.6, expect: '3'},
  {at: 1, expect: '4'},
  {at: 1.5, expect: '5'},
]);

test_interpolation({
  property: 'z-index',
  from: '-2',
  to: '-4'
}, [
  {at: -0.3, expect: '-1'},
  {at: 0, expect: '-2'},
  {at: 0.1, expect: '-2'},
  {at: 0.3, expect: '-3'},
  {at: 0.6, expect: '-3'},
  {at: 1, expect: '-4'},
  {at: 1.5, expect: '-5'},
]);

test_no_interpolation({
  property: 'z-index',
  from: 'auto',
  to: '10',
});
</script>
