public void TestDeleteDiagram_CallsDeleteDiagramWithSelectedDiagram()
{
var diagram = new DiagramModel();
_projectManagerMoq.SetupGet(m => m.CurrentDiagrams).Returns(new BindableCollection <DiagramModel> {
diagram
});
_projectExplorerViewModel.SelectedDiagram = diagram;
_projectExplorerViewModel.DeleteDiagram();
_projectManagerMoq.Verify(m => m.DeleteDiagram(It.Is <DiagramModel>(d => d == diagram)), Times.Once);
}