Added closed test

src/cpl_reactive_extensions/observable.py

@@ -1,4 +1,4 @@
-from typing import Callable, Union
+from typing import Callable, Union, Optional
 
 from cpl_reactive_extensions.observer import Observer
 
@@ -31,10 +31,12 @@ class Observable:
     def subscribe(
         self, observer_or_next: Union[Callable, Observer], on_error: Callable = None, on_complete: Callable = None
     ) -> Observer:
+        observable: Optional[Observable] = None
+        if isinstance(observer_or_next, Observable):
+            observable = observer_or_next
+
         if isinstance(observer_or_next, Callable):
             observer = Observer(observer_or_next, on_error, on_complete)
-        elif isinstance(observer_or_next, Observable):
-            observer = observer_or_next
         else:
             observer = observer_or_next
 
@@ -42,8 +44,8 @@ class Observable:
             self._observers.append(observer)
             return observer
 
-        if len(observer._observers) > 0:
-            for observer in observer._observers:
+        if observable is not None and len(observable._observers) > 0:
+            for observer in observable._observers:
                 self._call(observer)
         else:
             self._call(observer)

src/cpl_reactive_extensions/observer.py

@@ -16,6 +16,9 @@ class Observer:
         return self._closed
 
     def next(self, value: T):
+        if self._closed:
+            raise Exception("Observer is closed")
+
         self._on_next(value)
 
     def error(self, ex: Exception):
@@ -24,6 +27,7 @@ class Observer:
         self._on_error(ex)
 
     def complete(self):
+        self._closed = True
         if self._on_complete is None:
             return