Mock private methods of the class under test in jmockit

Question

I want to test process method of the ProcessServiceImpl class, with mocking private methods: readContent and isValidFile and userService class.

@Named("processServiceImpl")
public class ProcessServiceImpl {

    @Inject
    private UserService userService;

    public User process(Long userId, File inputFile) throws InvalidFileException {
        User user = userService.load(userId);
        String fileContent = readContent(inputFile);
        if (isValidFile(fileContent)) {
            User updatedUser = userService.updateUser(user, fileContent);
            return updatedUser;
        } else {
            throw new InvalidFileException();
        }
    }

    private String readContent(File inputFile) {
        //implementation
    }

    private boolean isValidFile(String fileContent) {
        //implementation
    }
}

I mocked up UserService and injected it successfully. but i can't mock the private methods of the class under the test. Based on this and this links i tried to mock them with NonStrictExpectations but it has not any invoke method!! Is there another way to do this? (I'm using jmockit-1.8)

new NonStrictExpectations(processServiceImpl) {{
    invoke(processServiceImpl, "readContent"); 
    result = "";
}};

Answer 1

The invoke(...) methods are from the mockit.Deencapsulation class.

But I would recommend to not mock the private methods. Instead, use a real file with valid contents for your tests.