Mock Python's built in print function

Question

I\'ve tried

from mock import Mock
import __builtin__

__builtin__.print = Mock()

But that raises a syntax error. I\'ve also tried patching

Answer 1

This Python 3 example builds upon the Python 2 answer by Krzysztof. It uses unittest.mock. It uses a reusable helper method for making the assertion.

import io
import unittest
import unittest.mock

from .solution import fizzbuzz


class TestFizzBuzz(unittest.TestCase):

    @unittest.mock.patch('sys.stdout', new_callable=io.StringIO)
    def assert_stdout(self, n, expected_output, mock_stdout):
        fizzbuzz(n)
        self.assertEqual(mock_stdout.getvalue(), expected_output)

    def test_only_numbers(self):
        self.assert_stdout(2, '1\n2\n')