e.should have(1).connections
e.should have(1).vertices
e.vertices.should include(v1)
+ v1.edges.should include(e)
e << v2
e.should have(2).connections
e.should have(2).vertices
e.vertices.should include(v1)
e.vertices.should include(v2)
+ v2.edges.should include(e)
end
it "adds several vertices to an edge" do