Use polling on macOS

Author: netheril96

test/simple_test.py

@@ -133,7 +133,16 @@ def __init__(self, p: subprocess.Popen):
         self.p = p
 
     def wait(self, timeout: Optional[float] = None) -> Any:
-        return self.p.communicate(timeout=timeout)
+        if sys.platform != "darwin":
+            return self.p.communicate(timeout=timeout)
+
+        # On macOS, communicate() with a timeout can be flaky, so we poll.
+        start_time = time.monotonic()
+        while self.p.poll() is None:
+            if timeout is not None and time.monotonic() - start_time >= timeout:
+                raise subprocess.TimeoutExpired(self.p.args, timeout)
+            time.sleep(0.032)
+        return self.p.communicate()
 
     @property
     def returncode(self) -> int: