Adding unit tests to WorkflowPlayer.py

src/components/workflows/Readme.md

@@ -4,10 +4,12 @@
 
 using `_id={WORKFLOW_DESIGNER_INSTANCE_ID}{session['user_id']}{get_unique_id()}`
 
-| Name          | value            |
-|---------------|------------------|
-| Canvas        | `c_{self._id}`   |
-| Designer      | `d_{self._id}`   |
-| Error Message | `err_{self._id}` |
-| Properties    | `p_{self._id}`   |
-| Spliter       | `s_{self._id}`   |
+| Name            | value              |
+|-----------------|--------------------|
+| Canvas          | `c_{self._id}`     |
+| Designer        | `d_{self._id}`     |
+| Error Message   | `err_{self._id}`   |
+| Properties      | `p_{self._id}`     |
+| Spliter         | `s_{self._id}`     |
+| Top element     | `t_{self._id}`     |
+