How to Disable Unit Tests Temporarily in Python?

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How to Skip Unit Tests Temporarily in Python?

Problem Formulation

Say, you’ve written a number of unit tests using the unittest module in Pyhton. How can you disable specific unit tests temporarily? In other words:

How to skip a unit test in Python’s unittest module?

Example: Given the following three unit tests.

def test_1():
    print('Test case 1')


def test_2():
    print('Test case 2')


def test_3():
    print('Test case 3')

How to disable tests 1 and 2?

Method 1: Skip Test with unittest.skip Decorator

You can disable individual tests by placing the @unittest.skip decorator in front of the function, class, or method definition.

  • Use @unittest.skip('Your reason for skipping') to give a reason for skipping it.
  • Use @unittest.skip if you don’t want to give a reason.

Here’s how you’d skip unit tests 1 and 2 in the provided example. 

@unittest.skip('Reason for skipping')
def test_1():
    print('Test case 1')


@unittest.skip
def test_2():
    print('Test case 2')


def test_3():
    print('Test case 3')

Method 2: Rename Tests to Skip

A simple and dirty, but effective method to skip tests is to prefix them with a single underscore. For example, rename your unit test function test_1 to _test_1 and it will be disabled. 

def _test_1():
    print('Test case 1')


def _test_2():
    print('Test case 2')


def test_3():
    print('Test case 3')

Method 3: Block Comment

Another alternative is to block comment the unit tests you want to disable using either the hashtag symbol # or the triple quotes '''def test ... ''' to comment out the test case. 

#def test_1():
#    print('Test case 1')

'''
def test_2():
    print('Test case 2')
'''

def test_3():
    print('Test case 3')

Summary

There are three ways to skip unit tests in Python:

  • Using the decorator @unittest.skip in front of the function to be skipped.
  • Adding a single underscore as a prefix such as in _test_1 instead of test_1.
  • Commenting out the method to be skipped.

You can see all three ways to skip the execution of the unit test in the following summarized example:

import unittest


class TestStringMethods(unittest.TestCase):

    def _test_1(self):
        print('test 1')

    # def test_2(self):
    #     print('test 2')

    @unittest.skip
    def test_3(self):
        print('test 3')


if __name__ == '__main__':
    unittest.main()

Now, none of the three functions are executed if you run this script.

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