Index: third_party/WebKit/LayoutTests/fast/layout/scroll-anchoring/feedback-loop.html |
diff --git a/third_party/WebKit/LayoutTests/fast/layout/scroll-anchoring/feedback-loop.html b/third_party/WebKit/LayoutTests/fast/layout/scroll-anchoring/feedback-loop.html |
new file mode 100644 |
index 0000000000000000000000000000000000000000..2bfe126d2c264769398928f19f913f217f593c61 |
--- /dev/null |
+++ b/third_party/WebKit/LayoutTests/fast/layout/scroll-anchoring/feedback-loop.html |
@@ -0,0 +1,53 @@ |
+<!DOCTYPE html> |
+<script src="../../../resources/testharness.js"></script> |
+<script src="../../../resources/testharnessreport.js"></script> |
+<style> |
+ |
+body { margin: 0; height: 5000px; } |
+#evil { height: 200px; width: 200px; background-color: #fcc; } |
+ |
+</style> |
+<div id="evil"></div> |
+<script> |
+ |
+internals.runtimeFlags.scrollAnchoringEnabled = true; |
+ |
+var kMaxAdjustments = 20; // Keep in sync with kMaxAdjustments in ScrollAnchor.cpp |
+ |
+var evil = document.querySelector('#evil'); |
+onscroll = () => { evil.style.marginTop = scrollY + "px"; }; |
+ |
+var frame = () => new Promise((resolve) => { requestAnimationFrame(resolve); }); |
+ |
+var waitFor = function(condition, failmsg, deadline) { |
+ if (!deadline) deadline = Date.now() + 1000; |
+ if (condition()) return Promise.resolve(); |
+ else if (Date.now() > deadline) return Promise.reject(failmsg); |
+ else return frame().then(() => waitFor(condition, failmsg, deadline)); |
+}; |
+ |
+var waitFrames = function(n, condition, failmsg) { |
+ var p = Promise.resolve(); |
+ var check = () => (!condition || condition() ? |
+ Promise.resolve() : Promise.reject(failmsg)); |
+ while (n--) |
+ p = p.then(check).then(frame); |
+ return p.then(check); |
+}; |
+ |
+var scrollSettlesAt = function(expectedY) { |
+ return waitFor(() => (scrollY == expectedY), |
+ "scroll did not reach " + expectedY) |
+ .then(() => waitFrames(3)) |
+ .then(() => waitFrames(3, () => (scrollY == expectedY), |
+ "scroll did not stay at " + expectedY)); |
+}; |
+ |
+promise_test(function() { |
+ var y = 10; |
+ return Promise.resolve() |
+ .then(() => { scrollTo(0, y); }) |
+ .then(() => scrollSettlesAt(y + kMaxAdjustments * y)); |
+}, "Scroll anchoring with scroll event handler feedback loop"); |
+ |
+</script> |