Part 4: Living Documentation (with examples)
Tags: testing, programming, writing
Published: 2023-01-13 21:10:36

Unit tests serve as living documentation for the code. They provide examples of how the code is intended to be used and how it should behave. This can be especially valuable for large codebases or projects with multiple developers, as it can make it easier for other developers to understand and maintain the code.

For example, consider a function that performs a specific operation on a list of data. A developer writes a unit test for this function by passing in a specific list of data, and then checks that the function returns the expected output. This not only documents the expected behavior of the code but also ensures that the code behaves as intended when the function is called with that specific list of data.

Unit tests can also be thought of as a form of executable documentation. They not only document the expected behavior of the code, but they also ensure that the code behaves as intended. This helps to bridge the gap between the code and the documentation, making it easier for developers to understand and work with the code.

For instance, a developer who is unfamiliar with a specific part of the codebase can look at the unit tests for that part of the code to understand how it is intended to be used, without having to read through the code itself.

Unit testing also helps to improve communication and collaboration between developers. By providing a clear and concise understanding of the code’s behavior, unit tests can help developers to understand the codebase and make changes with confidence. This can lead to faster development and fewer bugs.

For example, consider a large codebase with multiple developers working on it. If a developer makes a change to a specific part of the code, they can run the unit tests to ensure that their change does not break any existing functionality, and can also share their unit tests with other developers, which can help to ensure that the codebase is working as intended.

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Example Use Case:

Consider a software application that manages inventory for a warehouse. The development team is tasked with building a feature that allows managers to view and update the inventory levels. The team decides to implement unit testing as part of the development process to ensure that the feature is working as intended and to create a living documentation of the codebase.

The team writes several unit tests that cover different scenarios, such as adding a new item to inventory, updating the quantity of an existing item, and searching for an item by name. The tests are written in a clear and concise manner, and they provide a clear understanding of how the code should behave and how it can be used.

During development, the team runs these tests frequently to ensure that the code is working as intended. Once the feature is complete, the tests serve as a living documentation of the codebase, providing a clear and concise understanding of how the code should behave and how it can be used.

When new developers join the team, they can use the unit tests as a reference to understand the codebase and how it works. This helps to improve the overall maintainability and understandability of the codebase and also makes it easy for new developers to get up to speed quickly.

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In summary, unit tests serve as living documentation for the code. They provide examples of how the code is intended to be used, how it should behave, and ensure that the code behaves as intended. Unit tests can make it easier for other developers to understand and maintain the code, improve communication and collaboration between developers, and serve as a form of protection against regressions.

Series: Why unit testing is important ? All about unit testing

[Part 1: Introduction to Unit Testing](https://dev.to/svenherr/part-1-introduction-to-unit-testing-with-examples-21k2)

[Part 2: Catching Bugs Early](https://dev.to/svenherr/part-2-catching-bugs-early-b3f)

[Part 3: Ensuring Code Quality](https://dev.to/svenherr/part-3-ensuring-code-quality-with-examples-3p3n)

[Part 4: Living Documentation](https://dev.to/svenherr/part-4-living-documentation-with-examples-chk)

[Part 5: Continuous Integration and Deployment](https://dev.to/svenherr/part-5-continuous-integration-and-deployment-with-examples-2hkg)