add tests for functional apps

tests/test_app/test_plugins.py

@@ -57,7 +57,7 @@ def create_extension(
     )
 
 
-def test_Install_app(mock_extension_manager):
+def test_Install_app_class(mock_extension_manager):
     @define_app
     class uppercase:
         """Test app that converts a string to uppercase, and has a class docstring."""
@@ -71,6 +71,18 @@ def main(self, data: str) -> str:
     assert appercase("hello") == "HELLO"
     assert appercase.__doc__ in _make_apphelp_docstring(appercase.__class__)
 
+def test_Install_app_function(mock_extension_manager):
+    @define_app
+    def uppercase(data: str) -> str:
+        """Test function that converts a string to uppercase"""    
+        return data.upper()
+
+    mock_extension_manager([create_extension(uppercase)])
+
+    appercase = get_app("uppercase")
+    assert appercase("hello") == "HELLO"
+    assert appercase.__doc__ in _make_apphelp_docstring(appercase.__class__)
+
 
 @pytest.mark.parametrize("app_doc", [None, "text"])
 @pytest.mark.parametrize("init_doc", [None, "text"])