单元测试添加到邮取从拉链

Question

我有以下代码，用于增加向/从中提取拉链。我试图进行重构，这使它测试的准备。有人可以提供的指针，我怎么能做到这一点？旁白：我使用的最低采购量作为我的模拟框架和MSTest作为我的单元的测试工具

private const long BufferSize = 4096;

public static void ExtractZip(string zipFilename, string folder) {
  using (var zip = System.IO.Packaging.Package.Open(zipFilename, FileMode.OpenOrCreate)) {
    foreach (var part in zip.GetParts()) {
      using (var reader = new StreamReader(part.GetStream(FileMode.Open, FileAccess.Read))) {
        using (var writer = new FileStream(folder + "\\" + Path.GetFileName(part.Uri.OriginalString),
                                           FileMode.Create, FileAccess.Write)) {
          var buffer = System.Text.Encoding.UTF8.GetBytes(reader.ReadToEnd());
          writer.Write(buffer, 0, buffer.Length);
        }
      }
    }
  }
}

public static void AddFileToZip(string zipFilename, string fileToAdd) {
  using (var zip = System.IO.Packaging.Package.Open(zipFilename, FileMode.OpenOrCreate)) {
    var destFilename = ".\\" + Path.GetFileName(fileToAdd);
    var uri = PackUriHelper.CreatePartUri(new Uri(destFilename, UriKind.Relative));
    if (zip.PartExists(uri)) {
      zip.DeletePart(uri);
    }
    var part = zip.CreatePart(uri, "", CompressionOption.Normal);
    using (var fileStream = new FileStream(fileToAdd, FileMode.Open, FileAccess.Read)) {
      using (var dest = part.GetStream()) {
        CopyStream(fileStream, dest);
      }
    }
  }
}

在此先感谢。

Answer 1

我会使这两个静态的方法(ExtractZip和AddFileToZip)的实例的方法，并且把它变成一个接口：

public interface IZipper
{
  void ExtractZip(string zipFilename, string folder);
  void AddFileToZip(string zipFilename, string fileToAdd);
}

public class Zipper : IZipper
{
  public void ExtractZip(string zipFilename, string folder)
  { 
    //...
  }

  void AddFileToZip(string zipFilename, string fileToAdd)
  {
    //...
  }
}


// client code
class Foo
{
  private IZipper myZipper;
  // gets an instance of the zipper (injection), but implements only 
  // against the interface. Allows mocks on the IZipper interface.
  public Foo(IZipper zipper)
  {
    myZipper = zipper;
  }

}

客户代码现在很容易检测。

怎么样的拉链类？

• 考虑，如果这是值得考试呢。
• 在我们的项目，我们之间的区分单元的测试(分离)和融合的测试，它可使用的数据库或文件系统。你可以宣布它作为一个"文件系统的集成试验"。当然，只有测试目标的文件夹是允许的，可以使用。这不应该使任何问题。
• 考虑到移动的文件作出，并且只流。然后你可以很容易地测试的荏苒上的存储器流。该文件的行动仍然需要的地方，并不是进行测试。

Answer 2

摘要远创建后面FileStream IStreamProviders的，并将它传递到AddFileToZip和ExtractZip。除非你愿意做磁盘IO，在做单元测试，你将不得不抽象的文件系统操作。

Answer 3

我在这里粘贴最终的代码，因为它可能会帮助别人的同时也让我得到的反馈。 感谢与Stefan指着我在正确的方向。

/// <summary>
/// The commented methods are marked for future
/// </summary>
public interface IZipper
{
    //void Create();
    void ExtractAll();
    void ExtractAll(string folder);
    //void Extract(string fileName);
    void AddFile(string fileName);
    //void DeleteFile(string fileName);
}
public interface IZipStreamProvider
{
    Stream GetStream(string fileName);
}

public class ZipStreamProvider : IZipStreamProvider
{
    public Stream GetStream(string fileName)
    {
        //Create a read/writable file
        return new FileStream(fileName, FileMode.Create);
    }
}

public class Zipper : IZipper
{
    private const long BufferSize = 4096;
    public string ZipFileName { get; set;}

    //seam.. to use property injection
    private IZipStreamProvider ZipStreamProvider { get; set;}

    public Zipper(string zipFilename)
    {
        ZipFileName = zipFilename;
        //By default, write to file
        ZipStreamProvider = new ZipStreamProvider();
    }

    public void ExtractAll()
    {
        ExtractAll(Environment.CurrentDirectory);
    }

    public void ExtractAll(string folder)
    {
        using (var zip = System.IO.Packaging.Package.Open(ZipStreamProvider.GetStream(ZipFileName)))
        {
            foreach (var part in zip.GetParts())
            {
                using (var reader = new StreamReader(part.GetStream(FileMode.Open, FileAccess.Read)))
                {
                    using (var writer = ZipStreamProvider.GetStream(folder + "\\" + Path.GetFileName(part.Uri.OriginalString)))
                    {
                        var buffer = System.Text.Encoding.UTF8.GetBytes(reader.ReadToEnd());
                        writer.Write(buffer, 0, buffer.Length);
                    }
                }
            }
        }
    }

    public void AddFile(string fileToAdd)
    {
        using (var zip = System.IO.Packaging.Package.Open(ZipFileName, FileMode.OpenOrCreate))
        {
            var destFilename = ".\\" + Path.GetFileName(fileToAdd);
            var uri = PackUriHelper.CreatePartUri(new Uri(destFilename, UriKind.Relative));
            if (zip.PartExists(uri))
            {
                zip.DeletePart(uri);
            }
            var part = zip.CreatePart(uri, "", CompressionOption.Normal);
            using (var fileStream = ZipStreamProvider.GetStream(fileToAdd))
            {
                using (var dest = part.GetStream())
                {
                    CopyStream(fileStream, dest);
                }
            }
        }
    }

    private long CopyStream(Stream inputStream, Stream outputStream)
    {
        var bufferSize = inputStream.Length < BufferSize ? inputStream.Length : BufferSize;
        var buffer = new byte[bufferSize];
        int bytesRead;
        var bytesWritten = 0L;
        while ((bytesRead = inputStream.Read(buffer, 0, buffer.Length)) != 0)
        {
            outputStream.Write(buffer, 0, bytesRead);
            bytesWritten += bufferSize;
        }

        return bytesWritten;
    }
}