add unit test for correct regex
diff --git a/tests/tests_should_end_in_test_test.py b/tests/tests_should_end_in_test_test.py
index 2acfa17..4df2963 100644
--- a/tests/tests_should_end_in_test_test.py
+++ b/tests/tests_should_end_in_test_test.py
@@ -11,6 +11,10 @@
     assert ret == 1
 
 
+def test_regex():
+    assert main(('foo_test_py',)) == 1
+
+
 def test_main_django_all_pass():
     ret = main((
         '--django', 'tests.py', 'test_foo.py', 'test_bar.py',