What steps should be taken to eliminate class dependencies when writing a unit test?

To eliminate class dependencies when writing unit tests, the following steps are usually applied:

1. Use of interfaces or abstractions instead of concrete classes for dependencies. This allows replacing real implementations with test doubles.

2. Dependency Injection — passing dependencies through constructors, setters, or methods so that mocks or stubs can be substituted in tests.

3. Use of Mock objects with libraries like Mockito to simulate the behavior of dependencies.

4. Avoid creating dependencies directly inside the class under test (e.g., via new), and instead obtain them from outside.

Example:

public class Service {
    private final Repository repository;

    public Service(Repository repository) {
        this.repository = repository;
    }

    public String getData() {
        return repository.fetchData();
    }
}

// In the test
Repository mockRepo = Mockito.mock(Repository.class);
Mockito.when(mockRepo.fetchData()).thenReturn("test data");
Service service = new Service(mockRepo);
assertEquals("test data", service.getData());

Thus, the class becomes testable without depending on real implementations.