use Test::More tests => 4; use strict; use warnings; use Graph::Directed; my $graph = new Graph::Directed; $graph->add_edge(qw(a b)); $graph->add_edge(qw(b c)); is($graph, "a-b,b-c"); is(show_successors($graph), "a: b; b: c; c: "); $graph->set_vertex_attribute('b','label','bla'); is($graph, "a-b,b-c"); is(show_successors($graph), "a: b; b: c; c: "); sub show_successors { my $graph = shift; my @v; foreach my $v (sort $graph->vertices()) { push @v, "$v: " . join(" ", sort $graph->successors($v)); } return join("; ", @v); }