convert_service_ports takes only a dict as param

Signed-off-by: billou <nabil.benyoussef@gmail.com>

docker/types/services.py

@@ -560,11 +560,9 @@ class EndpointSpec(dict):
 
 
 def convert_service_ports(ports):
-    if isinstance(ports, list):
-        return ports
     if not isinstance(ports, dict):
         raise TypeError(
-            'Invalid type for ports, expected dict or list'
+            'Invalid type for ports, expected dict'
         )
 
     result = []

tests/unit/dockertypes_test.py

@@ -491,3 +491,9 @@ class ServicePortsTest(unittest.TestCase):
         } in converted_ports
 
         assert len(converted_ports) == 3
+
+    def test_convert_service_ports_wrong_ports_type(self):
+        ports = 'ports_as_string'
+
+        with pytest.raises(TypeError):
+            convert_service_ports(ports)