Python Testing

Python : Choosing a Test Runner

There are many test runners available for Python. The three most popular test runners are:

1. unittest
2. nose or nose2
3. pytest

PyUnit/ unittest

The one built into the Python standard library is called unittest. In this tutorial, you will be using unittest test cases and the unittest test runner. The principles of unittest are easily portable to other frameworks.

unit-test requires that:

• You put your tests into classes as methods
• You use a series of special assertion methods in the unittest.TestCase class instead of the built-in assert statement

To convert the test to a unittest test case, you would have to:

1. Import unittest from the standard library
2. Create a class called TestSum that inherits from the TestCase class
3. Convert the test functions into methods by adding self as the first argument
4. Change the assertions to use the self.assertEqual() method on the TestCase class
5. Change the command-line entry point to call unittest.main()

Note: Be careful if you’re writing test cases that need to execute in both Python 2 and 3. In Python 2.7 and below, unittest is called unittest2. If you simply import from unittest, you will get different versions with different features between Python 2 and 3.

Resource: https://docs.python.org/2/library/unittest.html

The Python unit testing framework, sometimes referred to as “PyUnit,” is a Python language version of Junit

unittest module supports test automation, sharing of setup and shutdown code for tests, aggregation of tests into collections, and independence of the tests from the reporting framework.

To achieve this, unittest supports some important concepts:

test fixture

A test fixture represents the preparation needed to perform one or more tests, and any associate cleanup actions.

test case

A test case checks for a specific response to a particular set of inputs. unittest provides a base class, TestCase, which may be used to create new test cases.

test suite

A test suite is a collection of test cases, test suites, or both. It is used to aggregate tests that should be executed together.

test runner

A test runner is a component which orchestrates the execution of tests and provides the outcome to the user. The runner may use a graphical interface, a textual interface, or return a special value to indicate the results of executing the tests.

A test runner is an object that provides a single method, run(), which accepts a TestCase or TestSuite object as a parameter, and returns a result object. The class TestResult is provided for use as the result object. unittest provides the TextTestRunner as an example test runner which reports test results on the standard error stream by default. Alternate runners can be implemented for other environments (such as graphical environments) without any need to derive from a specific class.