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

.gitignore

@@ -131,4 +131,3 @@ dmypy.json
 .config.yaml
 db
 noweb
-Session.vim

tests/test_message.py

@@ -84,12 +84,11 @@ class AnswerTestCase(CmmTestCase):
 
 class TestMessage(CmmTestCase):
 
+    @mock.patch('builtins.open',
+                mock.mock_open(read_data="TAGS: tag1 tag2\n=== QUESTION ===\nThis is a question\n=== ANSWER ===\nThis is an answer"))
     def test_from_file_txt(self) -> None:
         file_path = pathlib.Path('message.txt')
-        with mock.patch('chatmastermind.message.pathlib.Path.exists', return_value=True), \
+        with mock.patch('chatmastermind.message.pathlib.Path.exists', return_value=True):
-             mock.patch('builtins.open',
-                        mock.mock_open(
-                            read_data="TAGS: tag1 tag2\n=== QUESTION ===\nThis is a question\n=== ANSWER ===\nThis is an answer")):
             message = Message.from_file(file_path)
 
         self.assertIsInstance(message, Message)
@@ -102,18 +101,20 @@ class TestMessage(CmmTestCase):
         # TODO: Create a test yaml file
         pass
 
+    @mock.patch('builtins.open', mock.mock_open())
     def test_to_file_txt(self) -> None:
         file_path = pathlib.Path('message.txt')
         message = Message(Question('This is a question'),
                           Answer('This is an answer'),
                           {Tag('tag1'), Tag('tag2')},
                           file_path)
-        expected_content = "TAGS: tag1 tag2\n=== QUESTION ===\nThis is a question\n=== ANSWER ===\nThis is an answer\n"
-        # fake write
-        with mock.patch("builtins.open", mock.mock_open) as mock_fd:
         message.to_file(None)
-            mock_fd().assert_called_once_with(file_path, 'w')
+
-            mock_fd().write.assert_called_once_with(expected_content)
+        with open(file_path, "r") as fd:
+            file_contents = fd.read()
+
+        expected_contents = "TAGS: tag1 tag2\n=== QUESTION ===\nThis is a question\n=== ANSWER ===\nThis is an answer\n"
+        self.assertEqual(file_contents, expected_contents)
 
     def test_to_file_yaml(self) -> None:
         # TODO: Create a test yaml file