public void ClearOutEdges_Throws()
        {
            var wrappedGraph = new AdjacencyGraph <TestVertex, Edge <TestVertex> >();
            var graph        = new ClusteredAdjacencyGraph <TestVertex, Edge <TestVertex> >(wrappedGraph);

            // ReSharper disable once AssignNullToNotNullAttribute
            Assert.Throws <ArgumentNullException>(() => graph.ClearOutEdges(null));
        }