How TDD can benefit your Unity projects

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Test-Driven Development (TDD) is a software development methodology that involves writing tests for code before the actual code is written. This approach has several benefits for your projects, including improved code quality, enhanced code coverage, and reduced debugging time. In this article, you’ll learn how TDD can benefit your Unity projects.

In the beginning, it might feel, that your project is progressing slowly, but you will see the benefits of TDD later in development. It really speeds things up by having code that you KNOW is working. Then, you can really focus on implementing new features without thinking about old code. If you break something, you will see it immediately in failed tests.

First, let’s go through some of the benefits of using TDD in Unity projects.

Code reliability

The benefits of using TDD in Unity projects are numerous. First and foremost, it helps to improve code quality by ensuring that the code is thoroughly tested and functions as intended. This is achieved by writing tests that validate the code’s behavior and check for potential errors.

Code coverage

Using TDD also enhances code coverage, as it ensures that all aspects of the code are thoroughly tested. This is especially important in large and complex projects where it can be challenging to manually test every aspect of the code.

Reduced debugging time

In addition to these benefits, TDD can also reduce debugging time by helping developers to identify and fix errors early on in the development process. It can also enhance project documentation by providing a clear and detailed record of the tests that have been run and the results obtained.

Faster development

By using TDD, developers can quickly and confidently make changes to their code without having to manually test everything themselves. This can help speed up development by reducing the time spent on manual testing and debugging.

A case study involving Microsoft and IBM teams of software engineers concluded that the “teams experienced a 15-35% increase in initial development time” when they used the TDD technique. However, the study notes that these are numbers “subjectively estimated by management”.

When looked at from the perspective that Microsoft and IBM studies indicate that there were improvements in quality, it can be argued that, in the long run, TDD saves the time that would have been required to fix problems. The teams, at Microsoft and IBM, agreed with this view (Source). 

How to start using TDD in Unity

To start using test-driven development (TDD) in a Unity project, you’ll need to set up a testing framework and follow a few steps:

1. Identify the code you want to test: Decide which aspects of your game you want to test, such as gameplay mechanics, AI behavior, or graphics rendering.
2. Write tests: Write test cases that define the desired behavior of the code you want to test. These tests should be written before the code itself is written.
3. Run the tests: Run the tests to see if they fail (as they should since the code hasn’t been written yet). This will give you a baseline for evaluating the success or failure of the code you write later.
4. Write the code: Use the tests as a guide to write the code you want to test. Make sure that the code passes all of the tests you’ve written.
5. Refactor the code: If necessary, refactor the code to improve its structure or performance. Make sure that the refactored code still passes all of the tests.
6. Repeat the process: Continue the process of writing tests, writing code, and refactoring as needed until the feature you’re working on is complete.

If you’re using Rider, you can use its built-in test runner to easily manage and run your tests:

Why you shouldn’t learn TDD on your commercial Unity project

There are some potential dangers to using TDD for the first time on a commercial project. One potential danger is that using TDD can be time-consuming, especially if the development team is not familiar with the approach. It may take some time for the team to get accustomed to the TDD workflow and to learn how to write effective tests. This could lead to delays in the project schedule.

Another danger is that using TDD can be difficult to manage if the project has a tight deadline. In order to fully implement TDD, the development team must set aside time to write tests and make sure that the code passes all of the tests. This can be challenging in a fast-paced project environment.

Finally, there is a risk that the development team may not fully understand the benefits of TDD or how to implement it effectively. This could lead to problems with the code or difficulty maintaining the code over time.

Overall, it’s important to carefully consider the potential risks and benefits of using TDD on a commercial project before deciding to adopt this approach. It may be necessary to invest some time and resources in training and education to ensure that the team is able to effectively implement TDD.

Unit Testing

There are many techniques and approaches to writing and maintaining unit tests. If you are interested in learning about this topic, you might find one of our other articles interesting: Faking data substitution for tests in C# with Bogus