$ prove -v graph.t
graph.t .. 
ok 1 - Constructor returned defined value
ok 2 - An object of class 'Graph' isa 'Graph'
ok 3 - vertex Jolt
ok 4 - vertex Lord
ok 5 - vertex Tornado
ok 6 - Add edge Tornado      -> Jolt
ok 7 - Add edge Tornado      -> Lord
1..7
ok
All tests successful.
Files=1, Tests=7,  0 wallclock secs ( 0.02 usr  0.00 sys +  0.11 cusr  0.00 csys =  0.13 CPU)
Result: PASS