python - How to extract stdout redirection in unittest code to make it safe reusable by other test cases? -

i want test code includes print statements unfortunately can't rid of. approach capture stdout during tests , perform assertions on captured outputs. wanted extract redirection code make usable many test cases. example simple function this

# something.py  def function():     print("something")     return 42 

would tested this

import io import sys import unittest import  # test_something.py  class redirecttestcase(unittest.testcase):      def setup(self):         self.original_stdout = sys.stdout         self.temporary_stdout = io.stringio()         sys.stdout = self.temporary_stdout      def teardown(self):         sys.stdout = self.original_stdout      def assertoutputequal(self, expected_output):         self.temporary_stdout.seek(0)         captured_output = self.temporary_stdout.read().strip()         self.assertequal(expected_output, captured_output)   class testfunction(redirecttestcase):      def setup(self):         super().setup()      def teardown(self):         super().teardown()      def test_output(self):         something.function()         self.assertoutputequal("something")      def test_return(self):         self.assertequal(42, something.function())   if __name__ == "__main__":     unittest.main() 

i extracted stdout redirection code in base class, don't calling base classes setup , teardown methods in each test case implementation. there better way make approach accessible multiple test cases? especially, possible automatically call base classes setup , teardown make tests cleaner , safer? other suggestions improving testing approach highly appreciated!

i found blog post ned betchelder covering similar issue using mixin class. used approach restructure tests. divides code independent pieces , super() calls avoided in actual test cases.

class basetestcase(unittest.testcase):     """base test case."""      def setup(self):         super().setup()         # basic setup stuff here ...      def teardown(self):         # basic teardown stuff here ...         super().teardown()      def assertoutputequal(self, expected_output):         self.temporary_stdout.seek(0)         captured_output = self.temporary_stdout.read().strip()         self.assertequal(expected_output, captured_output)   class redirectmixin(object):     """mixin class redirecting stdout on setup , teardown."""      def setup(self):         super().setup()         self.original_stdout = sys.stdout         self.temporary_stdout = io.stringio()         sys.stdout = self.temporary_stdout      def teardown(self):         sys.stdout = self.original_stdout         super().teardown()   class testfunction(redirectmixin, basetestcase):     """actual test case using stdout redirection."""      def test_output(self):         something.function()         self.assertoutputequal("something")      def test_return(self):         self.assertequal(42, something.function())