message / chat: output improvements

tests/test_message.py

@@ -804,3 +804,27 @@ class MessageRenameTagsTestCase(CmmTestCase):
         self.message.rename_tags({(Tag('atag1'), Tag('atag2')), (Tag('btag2'), Tag('btag3'))})
         self.assertIsNotNone(self.message.tags)
         self.assertSetEqual(self.message.tags, {Tag('atag2'), Tag('btag3')})  # type: ignore [arg-type]
+
+
+class MessageToStrTestCase(CmmTestCase):
+    def setUp(self) -> None:
+        self.message = Message(Question('This is a question.'),
+                               Answer('This is an answer.'),
+                               tags={Tag('atag1'), Tag('btag2')},
+                               file_path=pathlib.Path('/tmp/foo/bla'))
+
+    def test_to_str(self) -> None:
+        expected_output = f"""{Question.txt_header}
+This is a question.
+{Answer.txt_header}
+This is an answer."""
+        self.assertEqual(self.message.to_str(), expected_output)
+
+    def test_to_str_with_tags_and_file(self) -> None:
+        expected_output = f"""{TagLine.prefix} atag1 btag2
+FILE: /tmp/foo/bla
+{Question.txt_header}
+This is a question.
+{Answer.txt_header}
+This is an answer."""
+        self.assertEqual(self.message.to_str(with_tags=True, with_file=True), expected_output)