public void ShouldExtraxctHtmlTags() { var linkRepo = Substitute.For <ILinksRepo>(); var webRepo = Substitute.For <IWebRepo>(); LinkProcessingService linkProcessingService = new LinkProcessingService(linkRepo, webRepo); var testUrl = "https://en.wikipedia.org/wiki/Mummia"; HtmlDocument html = new HtmlDocument { Text = File.ReadAllText("Resource\\Mummia.html") }; webRepo.DowloandPage(testUrl).Returns(html); IEnumerable <string> pagesLinks = new List <string> { "/wiki/Mumu", "https://ru.wikipedia.org/wiki/Ruru", "https://en.wikipedia.org/wiki/Trololo", "/wiki/LoLo" }; webRepo.GetAllTagsFromPage(html).Returns(pagesLinks); var testResult = linkProcessingService.ExtraxctHtmlTags(testUrl); webRepo.Received(1).DowloandPage(testUrl); webRepo.Received(1).GetAllTagsFromPage(html); Assert.AreEqual(testResult.Count, 3); }