public void GetDescendants_ByKey_ArgumentComparerIsInvoked()
{
// Get a valid tree.
var tree = TestTreeFactory.GetSimpleTree();
// Create a mock IComparer.
Mock <IEqualityComparer <Node <int> > > mockComparer = new Mock <IEqualityComparer <Node <int> > >();
mockComparer
.Setup(mock => mock.Equals(It.IsAny <Node <int> >(), It.IsAny <Node <int> >()))
.Returns(true);
// Create a VirtualTree.
VirtualTree <Node <int> > vt = VirtualTree.New(new NodeWalker <int>(), tree);
// Create a key to use for comparison. Any key is fine.
Node <int> key = new Node <int>(0);
// Execute GetDescendants.
vt.GetDescendants(key, mockComparer.Object).ToArray();
// Verify that the VirtualTree's comparer was used.
mockComparer.Verify(x => x.Equals(It.IsAny <Node <int> >(), It.IsAny <Node <int> >()), Times.Exactly(vt.GetDegree()));
}
