devtools/server/tests/chrome/suspendTimeouts_content.js

   1 "use strict";
   2
   3 // To make it easier to follow, this code is arranged so that the functions are
   4 // arranged in the order they are called.
   5
   6 const worker = new Worker("suspendTimeouts_worker.js");
   7 worker.onerror = error => {
   8   const message = `error from worker: ${error.filename}:${error.lineno}: ${error.message}`;
   9   throw new Error(message);
  10 };
  11
  12 // Create a message channel. Send one end to the worker, and return the other to
  13 // the mochitest.
  14 /* exported create_channel */
  15 function create_channel() {
  16   const { port1, port2 } = new MessageChannel();
  17   info(`sending port to worker`);
  18   worker.postMessage({ mochitestPort: port1 }, [port1]);
  19   return port2;
  20 }
  21
  22 // Provoke the worker into sending us a message, and then refuse to receive said
  23 // message, causing it to be delayed for later delivery.
  24 //
  25 // The worker will also post a message to the MessagePort we sent it earlier.
  26 // That message should not be delayed, as it is handled by the mochitest window,
  27 // not the content window. Its receipt signals that the test can assume that the
  28 // runnable for step 2) is in the main thread's event queue, so the test can
  29 // prepare for step 3).
  30 /* exported start_worker */
  31 function start_worker() {
  32   worker.onmessage = handle_echo;
  33
  34   // This should prevent worker.onmessage from being called, until
  35   // resumeTimeouts is called.
  36   //
  37   // This function is provided by test_suspendTimeouts.js.
  38   // eslint-disable-next-line no-undef
  39   suspendTimeouts();
  40
  41   // The worker should echo this message back to us and to the mochitest.
  42   worker.postMessage("HALLOOOOOO"); // suitable message for echoing
  43   info(`posted message to worker`);
  44 }
  45
  46 var resumeTimeouts_has_returned = false;
  47
  48 // Resume timeouts. After this call, the worker's message should not be
  49 // delivered to our onmessage handler until control returns to the event loop.
  50 /* exported resume_timeouts */
  51 function resume_timeouts() {
  52   // This function is provided by test_suspendTimeouts.js.
  53   // eslint-disable-next-line no-undef
  54   resumeTimeouts(); // onmessage handlers should not run from this call.
  55
  56   resumeTimeouts_has_returned = true;
  57
  58   // When this JavaScript invocation returns to the main thread's event loop,
  59   // only then should onmessage handlers be invoked.
  60 }
  61
  62 // The buggy code calls this handler from the resumeTimeouts call, before the
  63 // main thread returns to the event loop. The correct code calls this only once
  64 // the JavaScript invocation that called resumeTimeouts has run to completion.
  65 function handle_echo() {
  66   ok(
  67     resumeTimeouts_has_returned,
  68     "worker message delivered from main event loop"
  69   );
  70
  71   // Finish the mochitest.
  72   // This function is set and defined by test_suspendTimeouts.js
  73   // eslint-disable-next-line no-undef
  74   finish();
  75 }