@Spy and @Mock are two annotations provided by Mockito, a popular mocking framework for unit testing in Java. They are commonly used in conjunction with JUnit 5 to test Spring Boot applications.

@Spy creates a real object with real behavior, but also allows you to spy on and verify specific method calls made to that object during the test. It is often used when you want to test a class that has external dependencies, but you want to mock only some of its behavior.