1 files changed, 46 insertions, 0 deletions
diff --git a/devtools/client/inspector/animation/test/browser_animation_timing_negative-playback-rate_current-time-scrubber.js b/devtools/client/inspector/animation/test/browser_animation_timing_negative-playback-rate_current-time-scrubber.js
new file mode 100644
index 0000000000..f9906329ea
--- /dev/null
+++ b/devtools/client/inspector/animation/test/browser_animation_timing_negative-playback-rate_current-time-scrubber.js
@@ -0,0 +1,46 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test whether the scrubber was working in case of negative playback rate.
+
+add_task(async function () {
+  await addTab(URL_ROOT + "doc_negative_playback_rate.html");
+  await removeAnimatedElementsExcept([".normal"]);
+  const { animationInspector, panel } = await openAnimationInspector();
+
+  info("Set initial state");
+  clickOnCurrentTimeScrubberController(animationInspector, panel, 0);
+  await waitUntilAnimationsPlayState(animationInspector, "paused");
+  const initialCurrentTime =
+    animationInspector.state.animations[0].state.currentTime;
+  const initialProgressBarX = getProgressBarX(panel);
+
+  info("Check whether the animation currentTime was decreased");
+  clickOnCurrentTimeScrubberController(animationInspector, panel, 0.5);
+  await waitUntilCurrentTimeChangedAt(
+    animationInspector,
+    animationInspector.state.timeScale.getDuration() * 0.5
+  );
+  ok(
+    initialCurrentTime >
+      animationInspector.state.animations[0].state.currentTime,
+    "currentTime should be decreased"
+  );
+
+  info("Check whether the progress bar was moved to left");
+  ok(
+    initialProgressBarX > getProgressBarX(panel),
+    "Progress bar should be moved to left"
+  );
+});
+
+function getProgressBarX(panel) {
+  const areaEl = panel.querySelector(".keyframes-progress-bar-area");
+  const barEl = areaEl.querySelector(".keyframes-progress-bar");
+  const controllerBounds = areaEl.getBoundingClientRect();
+  const barBounds = barEl.getBoundingClientRect();
+  const barX = barBounds.x + barBounds.width / 2 - controllerBounds.x;
+  return barX;
+}