c# - 从文件夹中删除文件的单元测试方法

Question

我们有一个方法将文件夹名称和天数作为参数。

    public void Delete(string folder, int days)
    {
        var files = Directory.GetFiles(folder);

        foreach (var file in files)
        {
            var fi = new FileInfo(file);
            var fiCreationTime = fi.CreationTime;
            var deleteOlderThan= DateTime.Now.AddDays(-days);

            if (fiCreationTime >= deleteOlderThan) continue;
                fi.Delete();
        }
    }

在 C# 中对此类方法进行单元测试的最佳方法是什么

Answer 1

实际上您不能对您的方法进行单元测试，因为它依赖于外部 API(FileSystem、DateTime)。

所以你应该做的是分离逻辑并与外部源集成，它可能看起来像这样:

public class MyFileInfo
{
    public string FileName { get; set; }

    public DateTime CreationTime { get; set; }
}

public interface IDateTimeProvider
{
    DateTime GetCurrentTime();
}

public interface IMyFileSystemService
{
    IEnumerable<MyFileInfo> GetFileInfos(string folder);

    void DeleteFile(MyFileInfo myFileInfo);
}

public class MyService
{
    private readonly IMyFileSystemService _myFileSystemService;
    private readonly IDateTimeProvider _dateTimeProvider;

    public MyService(IMyFileSystemService myFileSystemService, IDateTimeProvider dateTimeProvider)
    {
        _myFileSystemService = myFileSystemService;
        _dateTimeProvider = dateTimeProvider;
    }

    public void Delete(string folder, int days)
    {
        var files = _myFileSystemService.GetFileInfos(folder);

        foreach (var file in files)
        {
            var deleteOlderThan = _dateTimeProvider.GetCurrentTime().AddDays(-days);

            if (file.CreationTime >= deleteOlderThan) continue;
            _myFileSystemService.DeleteFile(file);
        }
    }
}

我认为接口(interface) IDateTimeProvider 和 IMyFileSystemService 的实现应该不是问题。

现在您可以为 MyService.Delete 编写干净的单元测试