LayoutTests/ipc/deferred-reply.html

<!doctype html><!-- webkit-test-runner [ IPCTestingAPIEnabled=true ] -->
<title>Test that a receiver can defer its reply until a later message.</title>
<script src="../resources/testharness.js"></script>
<script src="../resources/testharnessreport.js"></script>
<script src="../resources/ipc.js"></script>
<body>
<script>

promise_test(async t => {
    if (!window.IPC)
        return;
    IPC.addTesterReceiver('UI');
    try {
        let deferredReply = IPC.sendWithPromisedReply('UI', 0, IPC.messages.IPCTester_SendDeferredReplyMessageToReceiver.name, [{type: 'int32_t', value: 42}]);
        IPC.sendMessage('UI', 0, IPC.messages.IPCTester_CompleteDeferredReplyOnReceiver.name, [{type: 'int32_t', value: 1000000}]);

        let result = await deferredReply;
        let swiftReceiverUsed = result.arguments[1].value;
        let sumOfBothArguments = 43 + 1000000;
        assert_equals(result.arguments[0].value, sumOfBothArguments + (swiftReceiverUsed ? 2 : 1));
    } finally {
        IPC.removeTesterReceiver('UI');
    }
    done();
}, "A reply deferred until a later message arrives.");
</script>
</body>