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// Here's how waitForNotification works:
//
// - myTestFunction0()
// - waitForNotification(myTestFunction1)
// - requestAnimationFrame()
// - Modify DOM in a way that should trigger an IntersectionObserver callback.
// - BeginFrame
// - requestAnimationFrame handler runs
// - Second requestAnimationFrame()
// - Style, layout, paint
// - IntersectionObserver generates new notifications
// - Posts a task to deliver notifications
// - Task to deliver IntersectionObserver notifications runs
// - IntersectionObserver callbacks run
// - Second requestAnimationFrameHandler runs
// - step_timeout()
// - step_timeout handler runs
// - myTestFunction1()
// - [optional] waitForNotification(myTestFunction2)
// - requestAnimationFrame()
// - Verify newly-arrived IntersectionObserver notifications
// - [optional] Modify DOM to trigger new notifications
//
// Ideally, it should be sufficient to use requestAnimationFrame followed
// by two step_timeouts, with the first step_timeout firing in between the
// requestAnimationFrame handler and the task to deliver notifications.
// However, the precise timing of requestAnimationFrame, the generation of
// a new display frame (when IntersectionObserver notifications are
// generated), and the delivery of these events varies between engines, making
// this tricky to test in a non-flaky way.
//
// In particular, in WebKit, requestAnimationFrame and the generation of
// a display frame are two separate tasks, so a step_timeout called within
// requestAnimationFrame can fire before a display frame is generated.
//
// In Gecko, on the other hand, requestAnimationFrame and the generation of
// a display frame are a single task, and IntersectionObserver notifications
// are generated during this task. However, the task posted to deliver these
// notifications can fire after the following requestAnimationFrame.
//
// This means that in general, by the time the second requestAnimationFrame
// handler runs, we know that IntersectionObservations have been generated,
// and that a task to deliver these notifications has been posted (though
// possibly not yet delivered). Then, by the time the step_timeout() handler
// runs, these notifications have been delivered.
//
// Since waitForNotification uses a double-rAF, it is now possible that
// IntersectionObservers may have generated more notifications than what is
// under test, but have not yet scheduled the new batch of notifications for
// delivery. As a result, observer.takeRecords should NOT be used in tests:
//
// - myTestFunction0()
// - waitForNotification(myTestFunction1)
// - requestAnimationFrame()
// - Modify DOM in a way that should trigger an IntersectionObserver callback.
// - BeginFrame
// - requestAnimationFrame handler runs
// - Second requestAnimationFrame()
// - Style, layout, paint
// - IntersectionObserver generates a batch of notifications
// - Posts a task to deliver notifications
// - Task to deliver IntersectionObserver notifications runs
// - IntersectionObserver callbacks run
// - BeginFrame
// - Second requestAnimationFrameHandler runs
// - step_timeout()
// - IntersectionObserver generates another batch of notifications
// - Post task to deliver notifications
// - step_timeout handler runs
// - myTestFunction1()
// - At this point, observer.takeRecords will get the second batch of
// notifications.
function waitForNotification(t, f) {
return new Promise(resolve => {
requestAnimationFrame(function() {
requestAnimationFrame(function() {
let callback = function() {
resolve();
if (f) {
f();
}
};
if (t) {
t.step_timeout(callback);
} else {
setTimeout(callback);
}
});
});
});
}
// If you need to wait until the IntersectionObserver algorithm has a chance
// to run, but don't need to wait for delivery of the notifications...
function waitForFrame(t, f) {
return new Promise(resolve => {
requestAnimationFrame(function() {
t.step_timeout(function() {
resolve();
if (f) {
f();
}
});
});
});
}
// The timing of when runTestCycle is called is important. It should be
// called:
//
// - Before or during the window load event, or
// - Inside of a prior runTestCycle callback, *before* any assert_* methods
// are called.
//
// Following these rules will ensure that the test suite will not abort before
// all test steps have run.
//
// If the 'delay' parameter to the IntersectionObserver constructor is used,
// tests will need to add the same delay to their runTestCycle invocations, to
// wait for notifications to be generated and delivered.
function runTestCycle(f, description, delay) {
async_test(function(t) {
if (delay) {
step_timeout(() => {
waitForNotification(t, t.step_func_done(f));
}, delay);
} else {
waitForNotification(t, t.step_func_done(f));
}
}, description);
}
// Root bounds for a root with an overflow clip as defined by:
// http://wicg.github.io/IntersectionObserver/#intersectionobserver-root-intersection-rectangle
function contentBounds(root) {
var left = root.offsetLeft + root.clientLeft;
var right = left + root.clientWidth;
var top = root.offsetTop + root.clientTop;
var bottom = top + root.clientHeight;
return [left, right, top, bottom];
}
// Root bounds for a root without an overflow clip as defined by:
// http://wicg.github.io/IntersectionObserver/#intersectionobserver-root-intersection-rectangle
function borderBoxBounds(root) {
var left = root.offsetLeft;
var right = left + root.offsetWidth;
var top = root.offsetTop;
var bottom = top + root.offsetHeight;
return [left, right, top, bottom];
}
function clientBounds(element) {
var rect = element.getBoundingClientRect();
return [rect.left, rect.right, rect.top, rect.bottom];
}
function rectArea(rect) {
return (rect.left - rect.right) * (rect.bottom - rect.top);
}
function checkRect(actual, expected, description, epsilon = 0) {
if (!expected.length)
return;
assert_approx_equals(actual.left, expected[0], epsilon, description + '.left');
assert_approx_equals(actual.right, expected[1], epsilon, description + '.right');
assert_approx_equals(actual.top, expected[2], epsilon, description + '.top');
assert_approx_equals(actual.bottom, expected[3], epsilon, description + '.bottom');
}
function checkLastEntry(entries, i, expected, epsilon = 0) {
assert_equals(entries.length, i + 1, 'entries.length');
if (expected) {
checkRect(
entries[i].boundingClientRect, expected.slice(0, 4),
'entries[' + i + '].boundingClientRect', epsilon);
checkRect(
entries[i].intersectionRect, expected.slice(4, 8),
'entries[' + i + '].intersectionRect', epsilon);
checkRect(
entries[i].rootBounds, expected.slice(8, 12),
'entries[' + i + '].rootBounds', epsilon);
if (expected.length > 12) {
assert_equals(
entries[i].isIntersecting, expected[12],
'entries[' + i + '].isIntersecting');
}
}
}
function checkJsonEntry(actual, expected) {
checkRect(
actual.boundingClientRect, expected.boundingClientRect,
'entry.boundingClientRect');
checkRect(
actual.intersectionRect, expected.intersectionRect,
'entry.intersectionRect');
if (actual.rootBounds == 'null')
assert_equals(expected.rootBounds, 'null', 'rootBounds is null');
else
checkRect(actual.rootBounds, expected.rootBounds, 'entry.rootBounds');
assert_equals(actual.isIntersecting, expected.isIntersecting);
assert_equals(actual.target, expected.target);
}
function checkJsonEntries(actual, expected, description) {
test(function() {
assert_equals(actual.length, expected.length);
for (var i = 0; i < actual.length; i++)
checkJsonEntry(actual[i], expected[i]);
}, description);
}
function checkIsIntersecting(entries, i, expected) {
assert_equals(entries[i].isIntersecting, expected,
'entries[' + i + '].target.isIntersecting equals ' + expected);
}
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