display: inline-block;
  padding: 10px;
}
.expected {
  background-color: green;
  margin-right: 10px;
}
</style>

<body></body>

<script>
test_interpolation({
  property: 'padding',
  from: neutralKeyframe,
  to: '20px',
}, [
  {at: -0.3, expect: '7px'},
  {at: 0, expect: '10px'},
  {at: 0.3, expect: '13px'},
  {at: 0.6, expect: '16px'},
  {at: 1, expect: '20px'},
  {at: 1.5, expect: '25px'},
]);

test_interpolation({
  property: 'padding',
  from: 'initial',
  to: '20px',
}, [
  {at: -0.3, expect: '0px'},