chapter-21.2-unittest.md

Chapter 21.2: Testing using unittest module

Table of contents:

• Chapter 21.2: Testing using unittest module
  • Introduction to unittest
    • Example of unittest
  • setUp and tearDown methods

Introduction to unittest

The unittest module is a python's builtin test module. It contains all basics of software testing, example: test discovery,assertion, setup/teardown, etc.

As python is an Object-oriented programming language, it's unittest module also implements Class-based interface to setup the test module. We can easily import unittest module to start testing our software.

Example of unittest

The following is a basic example of a testcase which will test for the correctness of the given function, "reverse_word".

import unittest

def reverse_word(word: str):
    return word[::-1]

class TestReverseWord(unittest.TestCase):
    def test_reverse():
        self.assertEqual(reverse_word("abcde"), "edcba")


if __name__ == "__main__":
    main()

setUp and tearDown methods

A setup method is a method that runs before each test. The setUp method generally initializes values before testcases are run. For example, If we need an authorization token to test an API, we can get them in the setUp method.

A tearDown method is a method that runs after each test. This method is used as a cleanup method after test gets executed.

An example of setup and teardowm methods are as follows:

def celsius_to_fahrenheit(celsius: float):
    return (9 / 5) * celsius + 32


class TestTemperatureChange(TestCase):
    def setUp(self) -> None:
        # This method runs before each test case inside of this test class
        self.celsius = 37

    def tearDown(self) -> None:
        # This method runs after each test case inside of this test class
        del self.celsius

    def test_conversion_from_setup(self):
        self.assertAlmostEqual(celsius_to_fahrenheit(self.celsius), 98.6)