Intermittent intersection-observer/timestamp.html) Make testing for expected time origins more reliable. Upstreamed from https://bugzilla.mozilla.org/show_bug.cgi?id=1369360 [ci skip]
diff --git a/intersection-observer/timestamp.html b/intersection-observer/timestamp.html index 9003256..be19800 100644 --- a/intersection-observer/timestamp.html +++ b/intersection-observer/timestamp.html
@@ -18,28 +18,17 @@ <div id="trailing-space" class="spacer"></div> <script> +// Pick this number to be comfortably greater than the length of two frames at 60Hz. +var timeSkew = 40; + var topWindowEntries = []; var iframeWindowEntries = []; var targetIframe; -var topWindowTimeOnTestStart; -var topWindowTimeBeforeCreatingIframe; var topWindowTimeBeforeNotification; var iframeWindowTimeBeforeNotification; -var timeSkew; - -function waitFor(numFrames, callback) { - if (numFrames <= 0) { - callback(); - return; - } - window.requestAnimationFrame(waitFor.bind(null, numFrames - 1, callback)); -} async_test(function(t) { - topWindowTimeOnTestStart = performance.now(); - waitFor(3, function () { - topWindowTimeBeforeCreatingIframe = performance.now(); - timeSkew = topWindowTimeBeforeCreatingIframe - topWindowTimeOnTestStart; + t.step_timeout(function() { targetIframe = document.createElement("iframe"); assert_true(!!targetIframe, "iframe exists"); targetIframe.src = "resources/timestamp-subframe.html"; @@ -66,7 +55,7 @@ runTestCycle(step1, "First rAF after iframe is loaded."); t.done(); }; - }); + }, timeSkew); }, "Check that timestamps correspond to the to execution context that created the observer."); function step1() { @@ -84,16 +73,14 @@ var topWindowTimeAfterNotification = performance.now(); var iframeWindowTimeAfterNotification = targetIframe.contentWindow.performance.now(); - // Test results are only significant if there's a gap between - // top window time and iframe window time. - assert_greater_than(topWindowTimeBeforeNotification, iframeWindowTimeAfterNotification, - "Time ranges for top and iframe windows are disjoint. Times: " + - [topWindowTimeOnTestStart, topWindowTimeBeforeCreatingIframe, - topWindowTimeBeforeNotification, topWindowTimeAfterNotification, - iframeWindowTimeBeforeNotification, iframeWindowTimeAfterNotification, - topWindowEntries[1].time - topWindowTimeBeforeNotification, - iframeWindowEntries[1].time - iframeWindowTimeBeforeNotification - ]); + assert_approx_equals( + topWindowEntries[1].time - topWindowTimeBeforeNotification, + iframeWindowEntries[1].time - iframeWindowTimeBeforeNotification, + // Since all intersections are computed in a tight loop between 2 frames, + // an epsilon of 16ms (the length of one frame at 60Hz) turned out to be + // reliable, even at slow frame rates. + 16, + "Notification times are relative to the expected time origins"); assert_equals(topWindowEntries.length, 2, "Top window observer has two notifications."); assert_between_inclusive( 