[test] Improve test_force_exit. NFC (#23597)

Split out from #23589

test/test_browser.py

@@ -1491,7 +1491,7 @@ def test_idbstore_sync_worker(self):
     self.btest('test_idbstore_sync_worker.c', expected='0', args=['-lidbstore.js', f'-DSECRET="{secret}"', '-O3', '-g2', '--proxy-to-worker', '-sASYNCIFY'])
 
   def test_force_exit(self):
-    self.btest_exit('force_exit.c', assert_returncode=10)
+    self.btest_exit('test_force_exit.c')
 
   def test_sdl_pumpevents(self):
     # key events should be detected using SDL_PumpEvents

test/test_core.py

@@ -2416,6 +2416,10 @@ def test_atexit(self):
       self.set_setting('EXIT_RUNTIME')
     self.do_core_test('test_atexit.c')
 
+  def test_force_exit(self):
+    self.set_setting('EXIT_RUNTIME')
+    self.do_run_in_out_file_test('test_force_exit.c')
+
   @no_lsan('https://github.com/emscripten-core/emscripten/issues/15988')
   def test_atexit_threads_stub(self):
     # also tests thread exit (__cxa_thread_atexit)

test/force_exit.c → test/test_force_exit.c

@@ -5,36 +5,39 @@
  * found in the LICENSE file.
  */
 
+#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <assert.h>
 #include <emscripten.h>
+#include <emscripten/eventloop.h>
 
-int result = 0;
+bool done = false;
 
-void EMSCRIPTEN_KEEPALIVE success() {
-  printf("success? %d\n", result);
-  assert(result == 10);
+void success() {
+  printf("atexit: done=%d\n", done);
+  assert(done);
 }
 
 void EMSCRIPTEN_KEEPALIVE later() {
   printf("later, now force an exit\n");
-  result += 10;
-  emscripten_force_exit(result);
+  done = true;
+  emscripten_force_exit(0);
 }
 
+EM_JS_DEPS(deps, "$callUserCallback")
+
 int main() {
   atexit(success);
 
   EM_ASM({
-    setTimeout(function() {
-      Module._later();
-    }, 1000);
+    // Use callUserCallback here so that ExitStatus is handled correctly
+    setTimeout(() => callUserCallback(Module._later), 1);
   });
 
   printf("exit, but still alive\n");
   emscripten_exit_with_live_runtime();
   __builtin_trap();
-  return 0;
+  return 99;
 }
 

test/test_force_exit.out

@@ -0,0 +1,3 @@
+exit, but still alive
+later, now force an exit
+atexit: done=1