One of the big problems running Unit Tests with Spring is what to do about @Value String string; fields. Since String can't be mocked, a lot of people are forced to use constructor injection or legacy getters/setters, leaving remnants of test code in their codebase.

Mockito Object Injection is a JUnit5 extension that can set arbitrary fields on your objects under test. This cleans up your codebase and avoids the use of poor-er alternatives, such as usage of reflection APIs in tests, constructor injection, getter/setters, package visible fields, etc.