diff --git a/tests/test_extends.py b/tests/test_extends.py
index 3cf9c2f..ce4662b 100644
--- a/tests/test_extends.py
+++ b/tests/test_extends.py
@@ -1,6 +1,19 @@
 import pytest
+from compose_viz.extends import Extends
 from compose_viz.service import Service
     
-def test_parse_file():
+def test_extend_init():
+    try:
+        Extends(service_name='frontend', from_file='tests/in/000001.yaml')
+        Extends(service_name='frontend')
+
+        assert True
+    except:
+        assert False
+
+    with pytest.raises(TypeError):
+        Extends(from_file='tests/in/000001.yaml')
+    
+def test_service_init():
     with pytest.raises(ValueError, match=r"Both image and extends are not defined in service 'frontend', aborting."):
         Service(name='frontend')