Mocking Stored Procedure Parameters Error

Here's a simplified test case:

using System;
using System.Data;
using System.Data.SqlClient;

using NUnit.Framework;
using TypeMock;

namespace slc.TypeMock.Test
{
   /// <summary>
   /// Summary description for MockReaderTest.
   /// </summary>
   public class TestClass
   {
      public void MockMultipleParametersMethod()
      {
         using (SqlConnection conn = new SqlConnection("Server=server; Database=db; User ID=user;Password=pwd"))
         using (SqlCommand command = new SqlCommand("dbo.usp_FOOSP", conn))
         {
            command.CommandType = CommandType.StoredProcedure;
            conn.Open();
            command.Parameters.Add("@param1", 1);
            command.Parameters.Add("@param2", 2);
            command.ExecuteNonQuery();
         }
      }
   }
   
   [TestFixture]
   public class ReaderClassTest
   {
      [Test]
      public void TestMultipleParameters()
      {
         MockManager.Init();
         MockManager.MockAll(typeof (SqlConnection)).ExpectCall("Open");
         
         MockManager.MockAll(typeof (SqlCommand)).ExpectAndReturn("ExecuteNonQuery", 1, 1);
         Mock parametersMock = MockManager.Mock(typeof(SqlParameterCollection));
         parametersMock.ExpectUnmockedCall("Add", 1).Args("@param1", 1);
         parametersMock.ExpectUnmockedCall("Add", 1).Args("@param2", 2);
         
         new TestClass().MockMultipleParametersMethod();
         MockManager.ClearAll();
      }
   }
}

Hi Scot
The reason for the message you got is that the Add method calls internally to another Add method.
The best solution in this case is to use the IParameters method 'When'.
'When' method is actually a conditional expectation.
Here is how it should be used in your code:

        [Test]
        public void TestMultipleParameters()
        {
            MockManager.Init();
            Mock mockSqlConnection = MockManager.MockAll(typeof(SqlConnection));
            mockSqlConnection.ExpectCall("Open");
            mockSqlConnection.ExpectCall("Close");

            MockManager.MockAll(typeof(SqlCommand)).ExpectAndReturn("ExecuteNonQuery", 1, 1);
            Mock parametersMock = MockManager.Mock(typeof(SqlParameterCollection), Constructor.NotMocked);

            parametersMock.ExpectUnmockedCall("Add", 1).When("@param1", 1);
            parametersMock.ExpectUnmockedCall("Add", 1).When("@param2", 2);

            new TestClass().MockMultipleParametersMethod();
            MockManager.ClearAll();
        } 

Two important notes:
1. Notice the line:

Mock parametersMock = MockManager.Mock(typeof(SqlParameterCollection), Constructor.NotMocked);

You can see that we don't want to mock the constructor otherwise we will get System.NullReferenceException inside the Add method.

2. The 'When' method is supported only in the enterprise version.