Migrated one regression test to pytest

tests/unit/regressions/direct_rule_call.py

-'''
-Created on Jul 6, 2014
-
-@author: igor
-'''
-import unittest
 from arpeggio import SemanticAction, ParserPython
 
-
-class Test(unittest.TestCase):
-
-    def test_direct_rule_call(self):
+def test_direct_rule_call():
     '''
     Test regression where in direct rule call semantic action is
     erroneously attached to both caller and callee.
@@ -35,5 +26,4 @@ class Test(unittest.TestCase):
     parse_tree = parser.parse("aa")
     parser.getASG()
 
-        self.assertEqual(call_count[0], 1,
-                         "Semantic action should be called once!")
+    assert call_count[0] == 1, "Semantic action should be called once!"