### Relevant articles

- [Introduction to Testing with Spock and Groovy](http://www.baeldung.com/groovy-spock)
- [Difference Between Stub, Mock, and Spy in the Spock Framework](https://www.baeldung.com/spock-stub-mock-spy)
- [Guide to Spock Extensions](https://www.baeldung.com/spock-extensions)