public void NavigationViewModel_Filter_GivenNull_ShouldOriginalCollection()
{
//------------Setup for test--------------------------
Init(false, true);
//------------Preconditions---------------------------
Assert.AreEqual(4, _vm.ExplorerItemModels[0].ChildrenCount);
_vm.Filter(model => model.ResourceType == ResourceType.WorkflowService);
Assert.AreEqual(2, _vm.ExplorerItemModels[0].ChildrenCount);
//------------Execute Test---------------------------
_vm.Filter(null);
//------------Assert Results-------------------------
Assert.AreEqual(2, _vm.ExplorerItemModels[0].ChildrenCount); // filter by environment Id
}