When writing Java unit tests:

1. Frameworks: Use JUnit 5 and Mockito.
2. Naming: Test method names should be descriptive, clearly stating what they test (e.g., givenX_whenY_thenZ or shouldReturnX_whenY).
3. AAA Pattern: Structure tests using Arrange-Act-Assert.
4. Mocking: Mock external dependencies (e.g., services, repositories) using Mockito.
5. Assertions: Use specific assertions from org.junit.jupiter.api.Assertions (e.g., assertEquals, assertTrue, assertThrows).
6. Coverage: Aim to test public methods of a class, covering different scenarios (happy path, edge cases, error conditions).
7. Test Isolation: Each test should be independent and not rely on the state or outcome of other tests.