This tutorial series focuses on the Mockito library - from basic to more advanced use cases, as well as integrating it with other useful testing libraries like JUnit.
If you have a few years of experience in the Java ecosystem, and you're interested in sharing that experience with the community (and getting paid for your work of course), have a look at the "Write for Us" page.
Cheers, Eugen
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Get started with Spring 5 and Spring Boot 2, through the Learn Spring course: