event_registry stores weakrefs, so remove_handler makes a ref to the passed function

esper/__init__.py

@@ -81,10 +81,11 @@ def remove_handler(name: str, func: _Callable[..., None]) -> None:
     receive the named event, or if the named event does
     not exist, this function call will pass silently.
     """
-    if func not in event_registry.get(name, []):
+    func_ref = _ref(func)
+    if func_ref not in event_registry.get(name, []):
         return
 
-    event_registry[name].remove(func)
+    event_registry[name].remove(func_ref)
     if not event_registry[name]:
         del event_registry[name]
 

tests/test_world.py

@@ -505,6 +505,16 @@ def handler():
     esper.dispatch_event("foo")
     assert called == 2
 
+def test_remove_handler():
+    def handler():
+        pass
+
+    assert esper.event_registry == {}
+    esper.set_handler("foo", handler)
+    assert "foo" in esper.event_registry
+    esper.remove_handler("foo", handler)
+    assert esper.event_registry == {}
+
 
 ##################################################
 #   Some helper functions and Component templates: