'Makes sure that validate_answer works.'

def test_validate_answer(self):

    sample_dict = {'x': (1, 2)}
    problem = self.build_problem(sample_dict=sample_dict, num_samples=10, tolerance='1%', answer='x')
    self.assertTrue(problem.responders.values()[0].validate_answer('14*x'))
    self.assertFalse(problem.responders.values()[0].validate_answer('3*y+2*x'))
