public void Init()
        {
            var navService = new Mock <INavigationService>();
            var dbService  = new Mock <IDatabaseService>();

            _newModel      = new SubstanceViewModel(nav: navService.Object, db: dbService.Object);
            _existingModel = new SubstanceViewModel(existingModel: LogSamples.TestSubstance,
                                                    nav: navService.Object, db: dbService.Object);
        }
 public void Cleanup()
 {
     _existingModel = _newModel = null;
 }