Final answer:
To mock authentication in Spring Boot, set up a MockMvc instance and use Mockito to create a mock authentication object. Inject the mock with SecurityMockMvcRequestPostProcessors.user in test cases to simulate user authentication.
Step-by-step explanation:
To mock authentication in Spring Boot tests, employ Mockito and Spring's SecurityMockMvcRequestPostProcessors.
Start by creating a MockMvc instance configured with SpringSecurity using MockMvcBuilders.
Define authentication mock behavior using Mockito to simulate an authenticated user.
Employ SecurityMockMvcRequestPostProcessors.user to construct a request post processor that establishes the necessary security context.
Execute test actions with mockMvc.perform(), passing the request post processor as an argument.
This step-by-step process enables the emulation of user authentication in a testing environment without the need for actual authentication actions, ensuring effective and controlled testing of security-related functionalities in Spring Boot applications.