Document expected return values of a pluging action

Author: robertisele

cmem_plugin_base/dataintegration/description.py

@@ -104,6 +104,10 @@ class PluginAction:
     They can be triggered from the plugin UI.
     Each action is based on a method on the plugin class. Besides the self parameter,
     the method can have one additional parameter of type PluginContext.
+    The return value of the method will be converted to a string and displayed in the UI.
+    The string may use Markdown formatting.
+    The method may return None, in which case no output will be displayed.
+    It may raise an exception to signal an error to the user.
 
     :param name: The name of the method.
     :param label: A human-readable label of the action

tests/test_description.py

@@ -102,17 +102,18 @@ def get_project(self, context: PluginContext) -> str:
 
         # There should be two actions
         assert len(plugin.actions) == 2
+        action1 = plugin.actions[0]
+        action2 = plugin.actions[1]
 
         # Check first action
-        action = plugin.actions[0]
-        assert action.name == "get_name"
-        assert action.label == "Get name"
-        assert action.description == "Returns the supplied name"
+        assert action1.name == "get_name"
+        assert action1.label == "Get name"
+        assert action1.description == "Returns the supplied name"
 
         # Call actions on a plugin instance
         plugin_instance = MyWorkflowPlugin("My Name")
-        assert action.execute(plugin_instance, TestPluginContext()) == "My Name"
-        assert action.execute(plugin_instance, TestPluginContext(project_id="movies")) == "movies"
+        assert action1.execute(plugin_instance, TestPluginContext()) == "My Name"
+        assert action2.execute(plugin_instance, TestPluginContext(project_id="movies")) == "movies"
 
 
 if __name__ == "__main__":