My motivation for chaining my class constructors here is so that I have a default constructor for mainstream use by my application and a second that allows me to inject a mock and a stub.

It just seems a bit ugly 'new'-ing things in the ":this(...)" call and counter-intuitive calling a parametrized constructor from a default constructor , I wondered what other people would do here?

(FYI -> SystemWrapper)

using SystemWrapper;

public class MyDirectoryWorker{

    //  SystemWrapper interface allows for stub of sealed .Net class.
    private IDirectoryInfoWrap dirInf;

    private FileSystemWatcher watcher;

    public MyDirectoryWorker()
        : this(
        new DirectoryInfoWrap(new DirectoryInfo(MyDirPath)),
        new FileSystemWatcher()) { }


    public MyDirectoryWorker(IDirectoryInfoWrap dirInf, FileSystemWatcher watcher)
    {
        this.dirInf = dirInf;
        if(!dirInf.Exists){
            dirInf.Create();
        }

        this.watcher = watcher;

        watcher.Path = dirInf.FullName;

        watcher.NotifyFilter = NotifyFilters.FileName;
        watcher.Created += new FileSystemEventHandler(watcher_Created);
        watcher.Deleted += new FileSystemEventHandler(watcher_Deleted);
        watcher.Renamed += new RenamedEventHandler(watcher_Renamed);
        watcher.EnableRaisingEvents = true;
    }

    public static string MyDirPath{get{return Settings.Default.MyDefaultDirPath;}}

    // etc...
}