Added failing unit tests for validation.

tests/test_validation.py

@@ -17,5 +17,8 @@ class TestValidation(TestCase):
     def test_intermediate_failure(self):
         self.assertFalse(validate('3a + a + b + 2b', '4a + 4b'))
 
+    #def test_indefinite_integral(self):
+    #    self.assertTrue(validate('int_2^4 x^2', '4^3/3 - 2^3/3'))
+
     #def test_advanced_failure(self):
     #    self.assertFalse(validate('(x-1)^3+(x-1)^3', '4a+4b'))