系统.InvalidOperationException:从具体化的'System.Int32'类型为可

我有一个特定的单元测试，在我的个人PC上运行良好，但每当我得到TFS运行测试时，它都会失败，并出现以下异常-

系统。InvalidOperationException:从物化的系统。Int32'类型为可空的'Country'类型有效。

通过遵循堆栈跟踪，它有一个问题，与以下方法-

public IEnumerable<IAddress> AddressSelectAll(long userID)
{
    using (var context = new Entities())
    {
        var addresses = context.Customers
                               .Where(x => x.UserId == userID)
                               .Select(y => new Address
                                                {
                                                    Address1 = y.Address1,
                                                    Address2 = y.Address2,
                                                    Address3 = y.Address3,
                                                    AddressID = y.AddressId,
                                                    City = y.City,
                                                    Country = y.Country != null ? (Country)y.Country : (Country?)null,
                                                    Postcode = y.Postcode,
                                                    State = y.State,
                                                    RecordEntryDate = y.RecordEntryDate,
                                                    Type = (AddressType)EFFunctions.ConvertToInt32(y.AddressType),
                                                    UserID = y.UserId
                                                }).ToList();
        return addresses.ToList();
    }
}

如果它是相关的(怀疑它是)，我的efffunctions类定义为-

public static class EFFunctions
{
    [EdmFunction("Model", "ConvertToInt32")]
    public static int ConvertToInt32(string text)
    {
        var result = string.IsNullOrEmpty(text) ? 0 : Convert.ToInt32(text);
        return result;
    }
}

我的。edmx中有以下内容-

<Function Name="ConvertToInt32" ReturnType="Edm.Int32">
  <Parameter Name="v" Type="Edm.String" />
  <DefiningExpression>
    CAST(v AS Edm.Int32)
  </DefiningExpression>
</Function>

有谁能告诉我我做错了什么吗?

Country = y.Country != null ? (Country)y.Country : (Country?)null