Using non-static injected services in JUnit Parameterized Tests

Question

I want to use Guice and GuiceBerry to inject a non-static legacy service into a factory class. I then want to inject that factory into my Parameterized JUnit test.

However, the issue is JUnit requires that the @Parameters method be static.

Example factory:

@Singleton
public class Ratings {
    @Inject
    private RatingService ratingService;

    public Rating classicRating() {
         return ratingService.getRatingById(1002)
    }

    // More rating factory methods
}

Example test usage:

@RunWith(Parameterized.class)
public class StaticInjectParamsTest {
    @Rule
    public GuiceBerryRule guiceBerryRule = new GuiceBerryRule(ExtendedTestMod.class)

    @Inject
    private static Ratings ratings;

    @Parameter
    public Rating rating;

    @Parameters
    public static Collection<Rating[]> ratingsParameters() {
    return Arrays.asList(new Rating[][]{
            {ratings.classicRating()}
            // All the other ratings
        });
    }

    @Test
    public void shouldWork() {
        //Use the rating in a test

    }
}

I've tried requesting static injection for the factory method but the Parameters method gets called before the GuiceBerry @Rule. I've also considered using just the rating's Id as the parameters but I want to find a reusable solution. Maybe my approach is flawed?

Answer 1

My solution was to add a RatingId class that wraps an integer and create a factory RatingIds that I could then return static and use as parameters. I overloaded the getRatingById method in my RatingService interface to accept the new RatingId type, and then inject the rating service into my test and use it directly.

Added factory:

public class RatingIds {
    public static RatingId classic() {
        return new RatingId(1002);
    }
    // Many more
}

Test:

@RunWith(Parameterized.class)
public class StaticInjectParamsTest {
    @Rule
    public GuiceBerryRule guiceBerryRule = new GuiceBerryRule(ExtendedTestMod.class)

    @Inject
    private RatingService ratingService

    @Parameter
    public RatingId ratingId;

    @Parameters
    public static Collection<RatingId[]> ratingsParameters() {
    return Arrays.asList(new RatingId[][]{
        {RatingIds.classic()}
        // All the other ratings
        });
    }

    @Test
    public void shouldWork() {
        Rating rating = ratingService.getRatingById(ratingId.getValue())
        //Use the rating in a test

    }
}