LayoutTests/webanimations/scheduling-of-css-animation-with-explicit-steps-timing-function-on-some-keyframes.html

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

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

    @keyframes anim {
        25% { margin-left: 250px }
        50% { margin-left: 500px; animation-timing-function: steps(5); }
        75% { margin-left: 750px }
    }

</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), 15, "Progress contained in the interval for an implicit 0% keyframe.");

    animation.currentTime = 265;
    assert_equals(internals.timeToNextAnimationTick(animation), 10, "Progress contained in the interval for an explicit keyframe with an implicit steps() timing-function.");

    animation.currentTime = 510;
    assert_equals(internals.timeToNextAnimationTick(animation), 40, "Progress contained in the interval for an explicit keyframe with an explicit steps() timing-function.");

    animation.currentTime = 780;
    assert_equals(internals.timeToNextAnimationTick(animation), 20, "Progress contained in the interval for an implicit 100% keyframe.");
}, "Computing the time until the next tick for a CSS Animation with implicit and explicit steps() timing functions.");

</script>