LayoutTests/webanimations/scheduling-of-css-animation-with-implicit-steps-timing-function.html

<script src="../resources/testharness.js"></script>
<script src="../resources/testharnessreport.js"></script>
<style>

    div {
        animation: anim 1s steps(10);
    }

    @keyframes anim {
        50% { margin-left: 500px; }
    }

</style>
<div></div>
<script>

promise_test(async t => {
    const animation = document.querySelector("div").getAnimations()[0];

    await animation.ready;

    animation.currentTime = 10;
    assert_equals(internals.timeToNextAnimationTick(animation), 40, "Progress contained in the interval for an implicit 0% keyframe.");

    animation.currentTime = 920;
    assert_equals(internals.timeToNextAnimationTick(animation), 30, "Progress contained in the interval for an implicit 100% keyframe.");
}, "Computing the time until the next tick for a CSS Animation with implicit steps() timing functions.");

</script>