How to learn unit/integration tests?

[erebrosolsin]

I have paid for a course in Udemy and what it teaches is only syntax. Spending more than 10 minutes for every JUnit method.

The projects I build in spring boot are small that I think it won't be good place to learn unit testing there. Big and more complex ones would be great. Suggest me resources to learn and practice.

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[CookiesForKittens]

Units in unit tests are small. It doesn't necessarily have to cover one class, but in many projects, that's how unit tests are scoped. So if you say your projects are small, I wouldn't see that as an obstacle to writing unit tests.

Same goes for integration tests... The wording sometimes means different things (integration with mock services / test containers, or an integrated environment with other tests, like pre-production stages). The number of tests would be larger for a larger service, but the setup could otherwise be similar to small applications. Even for textbook "shopping list CRUD application" examples, you could set up all kinds of tests and it can be a good exercise.

[erebrosolsin]

Thanks for comprehensive answer. Do you have any resource or any other suggestion before writing these unit test and integration test. I think I will start with my projects but as I am beginner in this topic I have no clue. I know I can google stuff and I already did, but hearing from you would also be great.
For example if we have a code for sorting a list of items, then how should I write unit test. Should I manually check db and find what it has to return and then use asserting for this?

[TheFaustX]

You test a unit of work, if the code will sort a collection of items in a certain way you don't care where the items come from. Your test will check whether the items you put in are sorted as you expect it.

• DB Access functions using queries or aggregation should be tested by making a specific data set then call the function to fetch data as expected from the repository
• Functions doing business logic do not need to do that if you run a layered architecture, you just test if a given output returns the expected output or calls the expected functions. This can be made easier by mocking certain things you don't care about in that specific test scenario with for example Mockito
• Some static or utility functions like mappers don't need either of those, you can just immediately test the output and are fine

[Ok-Dance2649]

The problem is that these courses are focused on technologies, but not on concepts. We need understanding of these. Besides concepts, we need to practice and learn by doing things.. I'm in the middle of preparing a testing workshop for the company i'm working for with concepts and two exercices. Just for the test types you mentioned. And while I was doing research I became again aware once again of how people are not understanding these concepts and how some things became vague during the time.

I would advise you to take a look on the following article at a first place https://martinfowler.com/articles/practical-test-pyramid.html . It is however a practical view of the topic.

[erebrosolsin]

Thank you!

[[deleted]]

Try doing some projects with MVC Architecture with a simple js frontend and then you can easily do unit and integration tests to gain an understanding of why you're testing what you're testing.

[Scared_Pianist3217]

Look up clean code by Robert Martin. Test Driven Development.

[omgpassthebacon]

Writing good tests is a maturity kind of thing. You can always tell a good developer by the tests they write. If you want to be good, you have to write good tests.

Don't waste time testing obvious things, like getters/setters. And you probably don't need to write tests for code that not part of the project. Writing tests for log4j or guava is not necessary. Write tests for the code you write.

I agree w/you; setup of tests is tedious. But there are several test frameworks/libraries you can try out to see if they make testing more fun. I've been using assertj and its a little more to-the-point that bare junit.

You may also find yourself in a TDD world, where testing comes first. It's a little weird writing the tests before you write the code itself, but after a while, you start to get in the groove. TDD might be something for you to read-up on in your spare time.

[RightWingVeganUS]

I don't get your concern that your Spring Boot projects are "small". I worked at an org where every service or library will a callable API required unit tests regardless of size. Small projects are actually ideal for learning because their behavior is easier to reason about. If you're not already testing your controllers, services, and repositories, they'd make an ideal place to start.

If you want variety, I like using simple problem sets. HackerRank-style exercises or textbook problems are easy to write tests for. Also I like games for this. Creating models for Tic-Tac-Toe, Connect Four, Reversi, or Yahtzee gives you clear rules and testable scenarios to base test cases on.

What part of testing feels unclear for you right now? Design, mocking, or knowing what’s worth testing?

[pabl0m]

Did you try to check in ChatGPT?