public void GetActorsNamesShouldReturnACollectionOfActors() { DbContextOptions <UltimateMoviesDbContext> options = new DbContextOptionsBuilder <UltimateMoviesDbContext>() .UseInMemoryDatabase(databaseName: "Movies_GetActorsNames_Database") .Options; UltimateMoviesDbContext db = new UltimateMoviesDbContext(options); IMoviesService moviesService = new MoviesService(db); db.Actors.Add(new Actor { Name = "Tester" }); db.Actors.Add(new Actor { Name = "Tester 2" }); db.SaveChanges(); db.ActorsMovies.Add(new ActorMovie { ActorId = db.Actors.ToList()[0].Id, MovieId = 1 }); db.ActorsMovies.Add(new ActorMovie { ActorId = db.Actors.ToList()[1].Id, MovieId = 1 }); db.SaveChanges(); List <Actor> actors = moviesService.GetActorsNames(1).ToList(); int actorsCount = actors.Count(); Assert.Equal(2, actorsCount); }