gitignore: added vim session file

.gitignore

@@ -130,4 +130,5 @@ dmypy.json
 
 .config.yaml
 db
-noweb
+noweb
+Session.vim

tests/test_message.py

@@ -1,5 +1,9 @@
+import pathlib
+import tempfile
+from typing import cast
 from .test_main import CmmTestCase
-from chatmastermind.message import source_code, MessageError, Question, Answer
+from chatmastermind.message import source_code, Message, MessageError, Question, Answer
+from chatmastermind.tags import Tag
 
 
 class SourceCodeTestCase(CmmTestCase):
@@ -76,3 +80,69 @@ class AnswerTestCase(CmmTestCase):
         answer = Answer("No")
         self.assertIsInstance(answer, Answer)
         self.assertEqual(answer, "No")
+
+
+class MessageToFileTxtTestCase(CmmTestCase):
+    def setUp(self) -> None:
+        self.file = tempfile.NamedTemporaryFile(delete=False, suffix='.txt')
+        self.file_path = pathlib.Path(self.file.name)
+        self.message = Message(Question('This is a question'),
+                               Answer('This is an answer'),
+                               {Tag('tag1'), Tag('tag2')},
+                               self.file_path)
+
+    def tearDown(self) -> None:
+        self.file.close()
+        self.file_path.unlink()
+
+    def test_to_file_txt(self) -> None:
+        self.message.to_file(self.file_path)
+
+        with open(self.file_path, "r") as fd:
+            content = fd.read()
+        expected_content = "TAGS: tag1 tag2\n=== QUESTION ===\nThis is a question\n=== ANSWER ===\nThis is an answer\n"
+        self.assertEqual(content, expected_content)
+
+    def test_to_file_unsupported_file_type(self) -> None:
+        unsupported_file_path = pathlib.Path("example.doc")
+        with self.assertRaises(MessageError) as cm:
+            self.message.to_file(unsupported_file_path)
+        self.assertEqual(str(cm.exception), "File type '.doc' is not supported")
+
+    def test_to_file_no_file_path(self) -> None:
+        """
+        Provoke an exception using an empty path.
+        """
+        with self.assertRaises(MessageError) as cm:
+            # clear the internal file_path
+            self.message.file_path = None
+            self.message.to_file(None)
+        self.assertEqual(str(cm.exception), "Got no valid path to write message")
+        # reset the internal file_path
+        self.message.file_path = self.file_path
+
+
+class MessageFromFileTxtTestCase(CmmTestCase):
+    def setUp(self) -> None:
+        self.file = tempfile.NamedTemporaryFile(delete=False, suffix='.txt')
+        self.file_path = pathlib.Path(self.file.name)
+        with open(self.file_path, "w") as fd:
+            fd.write("TAGS: tag1 tag2\n=== QUESTION ===\nThis is a question\n=== ANSWER ===\nThis is an answer\n")
+
+    def tearDown(self) -> None:
+        self.file.close()
+        self.file_path.unlink()
+
+    def test_from_file_txt(self) -> None:
+        message = Message.from_file(self.file_path)
+        self.assertIsInstance(message, Message)
+        self.assertEqual(message.question, 'This is a question')
+        self.assertEqual(message.answer, 'This is an answer')
+        self.assertSetEqual(cast(set[Tag], message.tags), {Tag('tag1'), Tag('tag2')})
+        self.assertEqual(message.file_path, self.file_path)
+
+    def test_from_file_not_exists(self) -> None:
+        file_not_exists = pathlib.Path("example.doc")
+        with self.assertRaises(MessageError) as cm:
+            Message.from_file(file_not_exists)
+        self.assertEqual(str(cm.exception), f"Message file '{file_not_exists}' does not exist")