from calculator import Calculator

class TddInPythonExample(unittest.TestCase):
    def test_calculator_add_method_returns_correct_result(self):
        calc = Calculator()
        result = calc.add(2, 2)
        self.assertEqual(4, result)

    def test_calculator_returns_error_message_if_both_args_not_numbers(self):
        self.assertRaises(ValueError, self.calc.add, 'two', 'three')

Traceback (most recent call last):
  File "C:Python27libsite-packagesnose-1.3.1-py2.7.eggnoseloader.py", line 411, in loadTestsFromNa
    addr.filename, addr.module)
  File "C:Python27libsite-packagesnose-1.3.1-py2.7.eggnoseimporter.py", line 47, in importFromPath
    return self.importFromDir(dir_path, fqname)
  File "C:Python27libsite-packagesnose-1.3.1-py2.7.eggnoseimporter.py", line 94, in importFromDir
    mod = load_module(part_fqname, fh, filename, desc)
  File "C:Devthinkcalculator_tests.py", line 10
    self.assertRaises(ValueError, self.calc.add, 'two', 'three')
       ^
IndentationError: expected an indented block