Simple example of testing a stored procedure return code parameter with Moq

StoredProcedureReturnCodeTesting

const string RETURN_CODE_NAME = "@return_code";
const int SP_RETURN_VALUE = 0;
Dictionary<string, SqlParameter> parameterList = null;
_mockSqlExecutor = new Mock<ISqlExecutor>();

_mockSqlExecutor.Setup(mdm =>
    mdm
    .ExecuteNonQuery(It.IsAny<string>(), It.IsAny<string>(), It.IsAny<Dictionary<string, SqlParameter>>()))
    .Callback(
      (string conn, string procName, Dictionary<string, SqlParameter> plist) =>
      {
          parameterList = plist;
          plist["RETURN_CODE_NAME"].Value = SP_RETURN_VALUE;
      });

//Do Stuff With Mock Sql Executor
    
 Assert.AreEqual(SP_RETURN_VALUE, (int)(parameterList["RETURN_CODE_NAME"].Value));

Hi,
Can I ask for what is the library ISqlExecutor belongs to?