public void ShouldRetrieveTagPictures() { var tagName = "myTag"; var mockRepository = new Mock <ITagRepository>(); mockRepository.Setup(r => r.GetPictures(tagName)).Returns(() => { var result = new List <PictureTag>(); result.Add(new PictureTag() { PictureId = Guid.NewGuid(), TagName = tagName }); result.Add(new PictureTag() { PictureId = Guid.NewGuid(), TagName = tagName }); return(result.AsQueryable()); }); var tagsController = new TagsController(mockRepository.Object); var pictureTags = tagsController.Pictures(tagName); Assert.AreEqual(pictureTags.Count(), 2); foreach (var pictureTag in pictureTags) { Assert.AreEqual(pictureTag.TagName, tagName); } }