Integrating IPathWrapper into the ReallyHardToTest class

ipathwrapper-integration.cs

// This is an example class illustrating some common patterns
// that negatively impact testability
// 
// In this round, we have removed the static dependency on 
// System.IO.Path
public class ReallyHardToTest{
  SomeModel model;
  IPathWrapper pathWrapper;
  
  public ReallyHardToTest(SomeOtherDependency otherDependency, IPathWrapper pathWrapper){
    this.pathWrapper = pathWrapper;
    model = new SomeModel();
    otherDependency.DoSomething();
  }
  
  public void SetFilename(string fileName){  
    model.Filename = pathWrapper.GetFileName(fileName);
  }
}

public class SomeModel{
  public string Filename{get;set;}
}

public class SomeOtherDependency{
  public void DoSomething(){
   // Just here for illustration 
  };
}