tests: added testcases for Message.from_file() and Message.to_file()

chatmastermind/message.py

@@ -171,14 +171,15 @@ class Message():
         """
         Create a Message from the given file. Expects the following file structures:
         For '.txt':
-            * TagLine
+            * TagLine [Optional]
             * Question.txt_header
             * Question
-            * Answer.txt_header
+            * Answer.txt_header [Optional]
+            # Answer [Optional]
         For '.yaml':
             * Question.yaml_key: single or multiline string
-            * Answer.yaml_key: single or multiline string
-            * Message.tags_yaml_key: list of strings
+            * Answer.yaml_key: single or multiline string [Optional]
+            * Message.tags_yaml_key: list of strings      [Optional]
         Returns 'None' if the message does not fulfill the tag requirements.
         """
         if not file_path.exists():
@@ -222,7 +223,7 @@ class Message():
 
     def to_file(self, file_path: Optional[pathlib.Path]) -> None:
         """
-        Write Message to the given file. Creates the following file structures:
+        Write a Message to the given file. Creates the following file structures:
         For '.txt':
             * TagLine
             * Question.txt_header