LayoutTests/performance-api/performance-observer-callback-mutate.html

<!DOCTYPE HTML>
<html>
<head>
<script src="../resources/js-test-pre.js"></script>
</head>
<body>
<script>
description("Test PerformanceObserver mutating itself while in its callback.");
window.jsTestIsAsync = true;

// Observer is first watching measures => then marks => measures => both.
// NOTE: Measures are sorted before marks due to startTime.

window.callbackCount = 0;
window.list = null;

let observer = new PerformanceObserver((list) => {
    window.list = list;
    callbackCount++;
    testPassed("PerformanceObserver callback fired");

    if (callbackCount === 1) {
        // Expected: [measure1]
        shouldBe(`list.getEntries().length`, `1`);
        shouldBeEqualToString(`list.getEntries()[0].entryType`, "measure");
        shouldBeEqualToString(`list.getEntries()[0].name`, "measure1");

        updateObserver(["mark"]);

        performance.mark("mark2");
        performance.measure("measure2");
    } else if (callbackCount === 2) {
        // Expected: [mark2]
        shouldBe(`list.getEntries().length`, `1`);
        shouldBeEqualToString(`list.getEntries()[0].entryType`, "mark");
        shouldBeEqualToString(`list.getEntries()[0].name`, "mark2");

        performance.mark("mark-before-change-observe-state-to-measure");
        performance.measure("measure-before-change-observe-state-to-measure");

        updateObserver(["measure"]);

        performance.mark("mark3");
        performance.measure("measure3");
    } else if (callbackCount === 3) {
        // Expected: [measure3, mark-before-change-observe-state-to-measure]
        shouldBe(`list.getEntries().length`, `2`);
        shouldBeEqualToString(`list.getEntries()[0].entryType`, "measure");
        shouldBeEqualToString(`list.getEntries()[0].name`, "measure3");
        shouldBeEqualToString(`list.getEntries()[1].entryType`, "mark");
        shouldBeEqualToString(`list.getEntries()[1].name`, "mark-before-change-observe-state-to-measure");

        performance.mark("mark-before-change-observe-state-to-both");
        performance.measure("measure-before-change-observe-state-to-both");

        updateObserver(["mark", "measure"]);

        performance.mark("mark4");
        performance.measure("measure4");
    } else if (callbackCount === 4) {
        // Expected: [measure-before-change-observe-state-to-both, measure4, mark4]
        shouldBe(`list.getEntries().length`, `3`);
        shouldBeEqualToString(`list.getEntries()[0].entryType`, "measure");
        shouldBeEqualToString(`list.getEntries()[0].name`, "measure-before-change-observe-state-to-both");
        shouldBeEqualToString(`list.getEntries()[1].entryType`, "measure");
        shouldBeEqualToString(`list.getEntries()[1].name`, "measure4");
        shouldBeEqualToString(`list.getEntries()[2].entryType`, "mark");
        shouldBeEqualToString(`list.getEntries()[2].name`, "mark4");

        performance.mark("mark-before-disconnect");
        performance.measure("measure-before-disconnect");

        observer.disconnect();

        performance.mark("mark-after-disconnect");
        performance.measure("measure-after-disconnect");

        setTimeout(finishJSTest, 50);
    } else if (callbackCount === 5)
        testFailed("Should not have received another callback, the observer was disconnected");

    for (let mark of list.getEntries())
        debug(" - " + mark.name);
});

function updateObserver(entryTypes) {
    debug("Observing: " + JSON.stringify(entryTypes));
    observer.observe({entryTypes});
}

updateObserver(["measure"]);
performance.mark("mark1");
performance.measure("measure1");
</script>
<script src="../resources/js-test-post.js"></script>
</body>
</html>