What is the difference between mocking and stubbing in testing?

What is the difference between mocking and stubbing in testing?

Mocking and stubbing are both techniques used in unit testing to isolate components. Stubbing provides predefined responses to calls made during the test, while mocking verifies that certain interactions occurred.

Can you give me an example of when to use a stub?

Sure! If you have a function that fetches data from an API, you can use a stub to return a fixed response without making an actual API call.

And what about mocking? When should I use that?

You would use mocking when you want to ensure that a specific method was called with the correct parameters. For instance, if you're testing a service that sends an email, you can mock the email-sending function to check if it was called.

Are there any downsides to using mocks?

Yes, overusing mocks can lead to fragile tests that break easily with changes in implementation. It's important to strike a balance.