add test for resultclass.

Author: dnozay

tests/testsuite.py

@@ -7,6 +7,7 @@
 
 from xmlrunner.unittest import unittest
 import xmlrunner
+from xmlrunner.result import _XMLTestResult
 import doctest
 import tests.doctest_example
 from six import StringIO, BytesIO
@@ -404,6 +405,15 @@ def test_xmlrunner_elapsed_times(self):
         suite.addTest(self.DummyTest('test_pass'))
         self._test_xmlrunner(suite)
 
+    def test_xmlrunner_resultclass(self):
+        class Result(_XMLTestResult):
+            pass
+
+        suite = unittest.TestSuite()
+        suite.addTest(self.DummyTest('test_pass'))
+        self.runner_kwargs['resultclass'] = Result
+        self._test_xmlrunner(suite)
+
     def test_xmlrunner_stream(self):
         stream = self.stream
         output = BytesIO()