@Test public void itShouldBeAdjacentToEachOther() throws Exception { WeightedEdge edge = new WeightedEdge(1, 2, 1.0); graph.addEdge(edge); assertThat(graph.adjacentTo(1), is(Collections.singletonList(edge))); assertThat(graph.adjacentTo(2), is(Collections.singletonList(edge))); }