fix: wire --regex-pattern through the CLI (#175)

slugify/__main__.py

@@ -76,6 +76,7 @@ def slugify_params(args: argparse.Namespace) -> dict[str, Any]:
         save_order=args.save_order,
         separator=args.separator,
         stopwords=args.stopwords,
+        regex_pattern=args.regex_pattern,
         lowercase=args.lowercase,
         replacements=args.replacements,
         allow_unicode=args.allow_unicode

test.py

@@ -574,6 +574,7 @@ class TestCommandParams(unittest.TestCase):
         'save_order': False,
         'separator': '-',
         'stopwords': None,
+        'regex_pattern': None,
         'lowercase': True,
         'replacements': None
     }
@@ -645,6 +646,17 @@ def test_two_text_sources_fails(self):
         self.assertEqual(err.exception.code, 2)
         self.assertIn("Input strings and --stdin cannot work together", cse.getvalue())
 
+    def test_regex_pattern(self):
+        # --regex-pattern must be passed through to slugify (issue #175).
+        params = self.get_params_from_cli('--regex-pattern', r'[^-a-z0-9_]+')
+        expected = self.make_params(regex_pattern=r'[^-a-z0-9_]+')
+        self.assertParamsMatch(expected, params)
+
+    def test_regex_pattern_end_to_end(self):
+        # The example from issue #175: underscores must survive the custom pattern.
+        params = self.get_params_from_cli('--regex-pattern', r'[^-a-z0-9_]+', '___This is a test___')
+        self.assertEqual(slugify(**params), '___this-is-a-test___')
+
     def test_multivalued_options_with_text(self):
         text = "the quick brown fox jumps over the lazy dog in a hurry"
         cli_args = "--stopwords the in a hurry -- {}".format(text).split()