response-body-read-task-handling.html

<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <title></title>
  <script src="/resources/testharness.js"></script>
  <script src="/resources/testharnessreport.js"></script>
</head>
<body>
  <script>
function performMicrotaskCheckpoint() {
    document.createNodeIterator(document, -1, {
        acceptNode() {
            return NodeFilter.FILTER_ACCEPT;
        }
    }).nextNode();
}

promise_test(function() {
    return fetch("../resources/data.json").then(function(response) {
        // Add a getter for "then" that will incidentally be invoked
        // during promise resolution.
        Object.prototype.__defineGetter__('then', () => {
            // Clean up behind ourselves.
            delete Object.prototype.then;

            // This promise should (like all promises) be resolved
            // asynchronously.
            var executed = false;
            Promise.resolve().then(_ => { executed = true; });

            // This shouldn't run microtasks!  They should only run
            // after the fetch is resolved.
            performMicrotaskCheckpoint();

            // The fulfill handler above shouldn't have run yet.  If it has run,
            // throw to reject this promise and fail the test.
            assert_false(executed, "shouldn't have run microtasks yet");

            // Otherwise act as if there's no "then" property so the promise
            // fulfills and the test passes.
            return undefined;
        });

        // Create a read request, incidentally resolving a promise with an
        // object value, thereby invoking the getter installed above.
        return response.body.getReader().read();
    });
}, "reading from a body stream should occur in a microtask scope");

promise_test(function() {
    return fetch("../resources/data.json").then(function(response) {
        // Add a getter for "then" that will incidentally be invoked
        // during promise resolution.
        Object.prototype.__defineGetter__('then', () => {
            // Clean up behind ourselves.
            delete Object.prototype.then;

            // This promise should (like all promises) be resolved
            // asynchronously.
            var executed = false;
            Promise.resolve().then(_ => { executed = true; });

            // This shouldn't run microtasks!  They should only run
            // after the fetch is resolved.
            performMicrotaskCheckpoint();

            // The fulfill handler above shouldn't have run yet.  If it has run,
            // throw to reject this promise and fail the test.
            assert_false(executed, "shouldn't have run microtasks yet");

            // Otherwise act as if there's no "then" property so the promise
            // fulfills and the test passes.
            return undefined;
        });

        // Create a read request, incidentally resolving a promise with an
        // object value, thereby invoking the getter installed above.
        return response.body.pipeTo(new WritableStream({
            write(chunk) {}
        }))
    });
}, "piping from a body stream to a JS-written WritableStream should occur in a microtask scope");
  </script>
</body>
</html>
chromium/third_party/blink/web_tests/external/wpt/fetch/api/response/response-body-read-task-handling.html
