AdjacencyMatrixGraph graph = new AdjacencyMatrixGraph();
graph.addVertex("A");
graph.addVertex("B");
graph.addVertex("C");
graph.addEdge("A", "B", 5);
graph.addEdge("A", "C", 4);
graph.addEdge("B", "C", 10);
assertEquals(5, graph.getEdgeValue("A", "B"));
assertEquals(4, graph.getEdgeValue("A", "C"));
assertEquals(10, graph.getEdgeValue("B", "C"));