refactor: split unit test class to have a common base class

tests/test_process_diff.py

@@ -9,13 +9,13 @@ from TodoParser import TodoParser
 from main import process_diff
 
 
-class IssueUrlInsertionTest(unittest.TestCase):
+class IssueUrlInsertionTestBase(unittest.TestCase):
     orig_cwd = None
     tempdir = None
     diff_file = None
     parser = None
 
-    def setUp(self):
+    def _setUp(self, diff_file):
         # get current working directory
         self.orig_cwd = os.getcwd()
 
@@ -24,12 +24,12 @@ class IssueUrlInsertionTest(unittest.TestCase):
 
         # run patch against the diff file to generate the simulated filesystem
         subprocess.run(['patch', '-d', self.tempdir.name,
-                        '-i', f'{os.getcwd()}/tests/test_new.diff'],
+                        '-i', f'{os.getcwd()}/tests/{diff_file}'],
                         stdout=subprocess.DEVNULL,
                         stderr=subprocess.DEVNULL,
                         check=True)
 
-        self.diff_file = open('tests/test_new.diff', 'r')
+        self.diff_file = open(f'tests/{diff_file}', 'r')
         self.parser = TodoParser()
         with open('syntax.json', 'r') as syntax_json:
             self.parser.syntax_dict = json.load(syntax_json)
@@ -37,6 +37,19 @@ class IssueUrlInsertionTest(unittest.TestCase):
         # change to the simulated filesystem directory
         os.chdir(self.tempdir.name)
 
+    def _tearDown(self):
+        # return to original working directory to ensure we don't mess up other tests
+        os.chdir(self.orig_cwd)
+
+        # explicitly cleanup to avoid warning being printed about implicit cleanup
+        self.tempdir.cleanup()
+        self.tempdir = None
+
+
+class IssueUrlInsertionTest(IssueUrlInsertionTestBase):
+    def setUp(self):
+        return super()._setUp('test_new.diff')
+
     # this test can take a while and, as far as TodoParser is concerned,
     # redundant with the tests of test_todo_parser, so enable the means
     # to skip it if desired
@@ -51,9 +64,4 @@ class IssueUrlInsertionTest(unittest.TestCase):
         self.assertEqual(output.getvalue().count('Issue URL successfully inserted'), 80)
 
     def tearDown(self):
-        # return to original working directory to ensure we don't mess up other tests
-        os.chdir(self.orig_cwd)
-
-        # explicitly cleanup to avoid warning being printed about implicit cleanup
-        self.tempdir.cleanup()
-        self.tempdir = None
+        return super()._tearDown()