public void CheckIfIngredientTypeExistByIdShouldWorkProperly() { var ingredientTypeRepository = new Mock <IRepository <IngredientType> >(); var ingredientRepository = new Mock <IRepository <Ingredient> >(); ingredientTypeRepository.Setup(x => x.All()).Returns(this.DummyDataIngredientType().AsQueryable()); var service = new IngredientService(ingredientTypeRepository.Object, ingredientRepository.Object); var actualResultWithExistingData = service.CheckIfIngredientTypeExistById(1); var actualResullWithNonExistingData = service.CheckIfIngredientTypeExistById(5); Assert.True(actualResultWithExistingData == true, "CheckIfIngredientTypeExistById with correct data should return True."); Assert.True(actualResullWithNonExistingData == false, "CheckIfIngredientTypeExistById with non existing data should return False."); }