public void RetrieveDictionarybyKey() { //arrange var vendorRepo = new VendorRepository(); var expected = new Dictionary <string, Vendor>() { { "Endava", new Vendor() { CompanyName = "Endava", Email = "*****@*****.**", VendorId = 1 } } }; var vendor1 = new Vendor() { CompanyName = "NTT", Email = "*****@*****.**", VendorId = 2 }; expected.Add(vendor1.CompanyName, vendor1); //act var act = vendorRepo.RetrieveDictionary(); CollectionAssert.AreEqual(expected, act.ToList()); //assert }