I am refactoring a class so that the code is testable (using NUnit and RhinoMocks as testing and isolations frameworks) and have found that I have found myself with a method is dependent on another (i.e. it depends on something which is created by that other method). Something like the following:

```
public class Impersonator
{
    private ImpersonationContext _context;

    public void Impersonate()
    {
        ...
        _context = GetContext();
        ...
    }

    public void UndoImpersonation()
    {
        if (_context != null)
            _someDepend.Undo();
    }
}

```

Which means that to test `UndoImpersonation`, I need to set it up by calling `Impersonate` (Impersonate already has several unit tests to verify its behaviour). This smells bad to me but in some sense it makes sense from the point of view of the code that calls into this class:

```
public void ExerciseClassToTest(Impersonator c)
{
     try
     {
         if (NeedImpersonation())
         {
             c.Impersonate();
         }
         ...
     }
     finally
     {
         c.UndoImpersonation();
     }
}

```

I wouldn't have worked this out if I didn't try to write a unit test for `UndoImpersonation` and found myself having to set up the test by calling the other public method. So, is this a bad smell and if so how can I work around it?