Typemock:从接口用存根替换类时出错

我正在使用Typemock进行一些单元测试。就我而言，我正在为执行平面文件数据处理的程序编写测试。为了对该程序进行单元测试，我编写了一些存根类，这些类实现了与实际版本相同的接口，但不是写入文件系统，而是包含它们写入的内部字符串。

现在我试图让 Typemock 在测试中用存根变体替换类的实际版本，但它给了我以下错误：System.InvalidOperationException ：可为空的对象必须具有值。

这是我尝试用我的存根替换的实际版本（包含更多，但错误不在那些行上）：

public class BatchRepository : IBatchRepository
    {
        private readonly string _connectionStringName;
        public BatchRepository(string connectionStringName) <-- Error triggers on this line
        {
            _connectionStringName = connectionStringName;
        }
}

存根类：

public class BatchRepositoryStub : IBatchRepository
{
    private readonly string _connectionStringName;
    public BatchRepositoryStub(string connectionStringName)
    {
        _connectionStringName = connectionStringName;
    }
}

测试

类和我的测试方法：

[TestClass]
public class InputTest
{
    // Variables
    private IBatchRepository _batchRepository;
    private ICommunicatieproductRepository _communicatieproductRepository;
    // Constants
    private const string ConnectionStringName = "Test";
    private const string InputFileLocation = "Temp";
    private const string ArchiefLocation = "Temp";
    private const string ErrorLocation = "Temp";
    private const string LoggingLocation = "Temp";
    private const int BatchGrootte = 1000;
    // Use TestInitialize to run code before running each test 
    [TestInitialize()]
    public void Initialize()
    {
         _batchRepository = new BatchRepositoryStub(ConnectionStringName);
        _communicatieproductRepository = new CommunicatieproductRepositoryStub(ConnectionStringName);
    }
    [TestMethod]
    public void CMBatch_FDInput_NewFileErrorOnEmptyRelatienummer()
    {
        // Arrange
        Isolate.Swap.NextInstance<IBatchRepository>().With(_batchRepository);
        Isolate.Swap.NextInstance<ICommunicatieproductRepository>().With(_communicatieproductRepository);
        var inputFileProcessor = new InputFileProcessor(InputFileLocation, ArchiefLocation, ErrorLocation, LoggingLocation, BatchGrootte, ConnectionStringName);
      }

}

实际过程，这会触发错误

public class InputFileProcessor
    {
        private readonly string _inputFileLocation;
        private readonly string _archiefLocation;
        private readonly string _errorLocation;
        private readonly string _loggingLocation;
        private readonly int _batchGrootte;
        private readonly IBatchRepository _batchRepository;
        private readonly ICommunicatieproductRepository _communicatieproductRepository;
        /// <summary>
        /// Constructor
        /// </summary>
        public InputFileProcessor(string inputFileLocation, string archiefLocation, string errorLocation, string loggingLocation, int batchGrootte, string connectionStringName)
        {
            _inputFileLocation = inputFileLocation;
            _archiefLocation = archiefLocation;
            _errorLocation = errorLocation;
            _loggingLocation = loggingLocation;
            _batchGrootte = batchGrootte;
            _batchRepository = new BatchRepository(connectionStringName);
            _communicatieproductRepository = new CommunicatieproductRepository(connectionStringName);          
        }
}

当从 InputFileProcessor 的构造函数调用时，该错误在 BatchRepository 的构造函数上触发。起初我以为参数连接字符串名称为空，但事实并非如此。为什么它最终会走上这条线？使用交换实例方法，我认为它甚至不会到达那里，而是最终进入存根类。我认为我的交换实例实现有问题，但我无法弄清楚。

我知道像这样的测试可能不完全是单元测试的内容，但它是测试程序输出和输入的最简单方法。例如，我需要确保无效文件触发相应的错误。能够轻松更改输入使其更易于管理。

// grab future
var futureInstanceHandle = Isolate.Fake.NextInstance<BatchRepository>();
// swap (ingoring type hiearchy)
Isolate.Swap.CallsOn(futureInstanceHandle).WithCallsTo(_batchRepositorystub);