Subscribeon: test that the right scheduler is passed to the subscribe…

… function of the source.

tests/test_observable/test_subscribeon.py

@@ -1,6 +1,6 @@
 import unittest
 
-from reactivex import operators as ops
+from reactivex import operators as ops, create as rx_create
 from reactivex.testing import ReactiveTest, TestScheduler
 
 on_next = ReactiveTest.on_next
@@ -71,6 +71,28 @@ def create():
         assert results.messages == []
         assert xs.subscriptions == [subscribe(200, 1000)]
 
+    def test_subscribe_on_scheduler_forwarding(self):
+        scheduler = TestScheduler()
+        forwarded_sheduler = None
+
+        def source():
+            def subscribe(observer, _scheduler):
+                nonlocal forwarded_sheduler
+                forwarded_sheduler = _scheduler
+
+                def action_on_completed(_, __):
+                    observer.on_completed()
+
+                return _scheduler.schedule_absolute(250, action_on_completed)
+
+            return rx_create(subscribe)
+
+        def create():
+            return source().pipe(ops.subscribe_on(scheduler))
+
+        results = scheduler.start(create)
+        assert forwarded_sheduler is scheduler
+        assert results.messages == [on_completed(250)]
 
 if __name__ == "__main__":
     unittest.main()