Ensure unittest are directly executables

Author: kiorky

src/croniter/tests/test_croniter.py

@@ -1,7 +1,10 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
+try:
+    import unittest2 as unittest
+except ImportError:
+    import unittest
 
-import unittest
 from datetime import datetime, timedelta
 from functools import partial
 from time import sleep

src/croniter/tests/test_croniter_hash.py

@@ -1,5 +1,11 @@
 import random
 import uuid
+
+try:
+    import unittest2 as unittest
+except ImportError:
+    import unittest
+
 from datetime import datetime, timedelta
 
 from croniter import CroniterBadCronError, CroniterNotAlphaError, croniter
@@ -545,3 +551,7 @@ def test_expand_years_by_range_and_division(self):
         assert len(years) == 31
         assert min(years) == 2020
         assert max(years) == 2050
+
+
+if __name__ == "__main__":
+    unittest.main()

src/croniter/tests/test_croniter_random.py

@@ -1,3 +1,8 @@
+try:
+    import unittest2 as unittest
+except ImportError:
+    import unittest
+
 from datetime import datetime, timedelta
 
 from croniter import croniter
@@ -42,3 +47,7 @@ def test_random_with_year(self):
         result = obj.get_next(datetime)
         self.assertGreaterEqual(result.year, 2025)
         self.assertLessEqual(result.year, 2030)
+
+
+if __name__ == "__main__":
+    unittest.main()