(fix) Fixes #3648 (#3649)

* (fix) Fixes #3648

* (fix) formatting

* (review) add assertion for exception thrown

moto/elbv2/models.py

@@ -827,9 +827,10 @@ Member must satisfy regular expression pattern: {}".format(
         for load_balancer in self.load_balancers.values():
             for listener_arn in listener_arns:
                 listener = load_balancer.listeners.get(listener_arn)
-                if not listener:
-                    raise ListenerNotFoundError()
-                matched.append(listener)
+                if listener:
+                    matched.append(listener)
+        if listener_arns and len(matched) == 0:
+            raise ListenerNotFoundError()
         return matched
 
     def delete_load_balancer(self, arn):

tests/test_elbv2/test_elbv2.py

@@ -415,10 +415,9 @@ def test_create_target_group_and_listeners():
     response.get("LoadBalancers").should.have.length_of(0)
 
     # And it deleted the remaining listener
-    response = conn.describe_listeners(
-        ListenerArns=[http_listener_arn, https_listener_arn]
-    )
-    response.get("Listeners").should.have.length_of(0)
+    with pytest.raises(ClientError) as e:
+        conn.describe_listeners(ListenerArns=[http_listener_arn, https_listener_arn])
+    e.value.response["Error"]["Code"].should.equal("ListenerNotFound")
 
     # But not the target groups
     response = conn.describe_target_groups()