message: improved robustness of Question and Answer content checks and tests

tests/test_message.py

@@ -61,22 +61,39 @@ class SourceCodeTestCase(CmmTestCase):
 
 
 class QuestionTestCase(CmmTestCase):
-    def test_question_with_prefix(self) -> None:
+    def test_question_with_header(self) -> None:
         with self.assertRaises(MessageError):
-            Question("=== QUESTION === What is your name?")
+            Question(f"{Question.txt_header}\nWhat is your name?")
 
-    def test_question_without_prefix(self) -> None:
+    def test_question_with_answer_header(self) -> None:
+        with self.assertRaises(MessageError):
+            Question(f"{Answer.txt_header}\nBob")
+
+    def test_question_with_legal_header(self) -> None:
+        """
+        If the header is just a part of a line, it's fine.
+        """
+        question = Question(f"This is a line contaning '{Question.txt_header}'\nWhat does that mean?")
+        self.assertIsInstance(question, Question)
+        self.assertEqual(question, f"This is a line contaning '{Question.txt_header}'\nWhat does that mean?")
+
+    def test_question_without_header(self) -> None:
         question = Question("What is your favorite color?")
         self.assertIsInstance(question, Question)
         self.assertEqual(question, "What is your favorite color?")
 
 
 class AnswerTestCase(CmmTestCase):
-    def test_answer_with_prefix(self) -> None:
+    def test_answer_with_header(self) -> None:
         with self.assertRaises(MessageError):
-            Answer("=== ANSWER === Yes")
+            Answer(f"{Answer.txt_header}\nno")
 
-    def test_answer_without_prefix(self) -> None:
+    def test_answer_with_legal_header(self) -> None:
+        answer = Answer(f"This is a line contaning '{Answer.txt_header}'\nIt is what it is.")
+        self.assertIsInstance(answer, Answer)
+        self.assertEqual(answer, f"This is a line contaning '{Answer.txt_header}'\nIt is what it is.")
+
+    def test_answer_without_header(self) -> None:
         answer = Answer("No")
         self.assertIsInstance(answer, Answer)
         self.assertEqual(answer, "No")