What is unit testing and how does it work?
Jan 19, 2023
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What is unit testing and how does it work?
Unit testing is a software testing method in which individual units or components of a software application, such as functions or classes, are tested in isolation from the rest of the system. The goal of unit testing is to validate that each unit of the software application is working as intended, and to detect and fix any bugs early in the development process.
Unit tests are typically written by developers as they write the code, and are automated so they can be easily run as part of the software development process. They typically include test inputs, the expected output, and a call to the function or class being tested. The test will then compare the output from the function or class to the expected output, and report any differences as failures.
Unit testing helps to ensure that code changes don't break existing functionality, and can also be used as a form of documentation, as the tests can serve as examples of how the code is intended to be used.
What is an example of unit testing?
An example of a unit test for a function that performs a mathematical calculation might look something like this:
This test includes test inputs, in this case a list of numbers and expected result, a call to the function calculate_average which is being tested, and a comparison between the output result and the expected output. If the function is working correctly, the assert statement should not raise an exception, otherwise it will raise an AssertionError and the test will be considered as failed.
Another example could be a class test which looks like this:
Here, we're testing the __init__ method of Person class which initialize the class with name and age, and the test verifies if it's initialized correctly by comparing the string representation of the object with expected output.
These are just examples, the implementation details will vary depending on the programming language and the testing framework being used.
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Fullstack software engineer and tech mentor to product managers. Follow Irene on Medium!