Why is unit testing so important in agile? [closed]

Question

I still read that without unit testing, you cannot be agile. While I understand the purpose of unit tests, why they are so crucial in agile? Is it because the frequent builds might easily brake something? And what about integration testing in agile, is that the same case? Thanks

Answer 1

"...without unit testing, you cannot be agile". Strictly speaking, that is a false statement. Agile doesn't prescribe a particular testing methodology. Anybody who tells you otherwise doesn't understand agile. Agile is about delivering high quality code and being able to respond to change. If you can do that without writing unit tests, you can still be agile.

That being said, unit tests are an important part of software development no matter what the methodology. It's difficult to write high quality software on a large scale without them. They help you determine that the individual units of your code are behaving the way they are designed. Whether you use unit tests, and how many unit tests you write, is a factor of how important it is that your code is correct, how hard it is to fix defects if they make it into production, and so on.

I would say that for most projects, having a robust, well-maintained set of unit and integration tests helps your team be more agile. Having a good set of unit tests is very liberating as a developer -- you are free to make changes more quickly because you have a safety net. This makes it easier to quickly develop stories and verify they are correct.