// Below RecentlyUsedTrackerConfiguration provides configuration information through property exports. MEF pulls on the property getters and exports that info. 
// If the part needs to be data drvien, you can still access a service behind the scenes in the getter (or the constructor) to get the info.
 
public class RecentlyUsedTrackerConfiguration
{
  public RecentlyUsedTrackerConfiguration()
  {
     //set values here
  }
 
  [Export("RecentlyUsedTracker.File")]
  public string File {get;set;}
 
  [Export("RecentlyUsedTracker.MaxItems")]
  public int MaxItems {get;set;}
}
 
// The consumer is completely insulated and simply imports....such as below.
 
public class RecentlyUsedTracker {
  [Import("RecentlyUsedTracker.File")]
  public string File {get;set;}
 
  [Import("RecnetlyUsedTracker.MaxItems")]
  public int MaxItems {get;set;}
}
 
// RecentlyUsedTracker imports the config info above. Now for testing you just pass in the values you need in the test.