[TestMethod()]//check modelstate if valid credentials are passed
        public void GetValidationErrorMessagesTestForValidModel()
        {
            //Arrange

            AvaTaxProfileAssistantHelperTests taxProfileAsstHelper = new AvaTaxProfileAssistantHelperTests();

            TryValidateModel(input.AccountCredentials);
            string ErrorString = "";

            //Act
            AvaTaxProfileAssistantHelper.GetValidationErrorMessages(ModelState, ref ErrorString);

            //Assert
            Assert.IsTrue(ModelState.IsValid, "Model state cannot be false when valid credentials are passed!!");
        }
        [TestMethod()]//check modelstate and if false return errorstring
        public void GetValidationErrorMessagesTestForInvalidModel()
        {
            //Arrange
            xmlReader = XmlReader.Create(@"..\XMLTestFiles\TPA_1000_AccountCredentialsMissing.xml");
            var tpa        = new TPAScaffold();
            var serializer = new XmlSerializer(tpa.GetType());

            input = (TPAScaffold)serializer.Deserialize(xmlReader);
            AvaTaxProfileAssistantHelperTests taxProfileAsstHelper = new AvaTaxProfileAssistantHelperTests();

            TryValidateModel(input.AccountCredentials);
            string ErrorString = "";

            //Act
            AvaTaxProfileAssistantHelper.GetValidationErrorMessages(ModelState, ref ErrorString);

            //Assert
            Assert.AreEqual(false, ModelState.IsValid, "Model state cannot be true when invalid credentials are passed!!");
        }