use Test::More tests => 18;
use Graph;
my $g = Graph->new;
$g->add_path('a'..'d');
ok( $g->has_vertex('a'));
ok( $g->has_vertex('b'));
ok( $g->has_vertex('c'));
ok( $g->has_vertex('d'));
$g->delete_vertex('d');
ok( $g->has_vertex('a'));
ok( $g->has_vertex('b'));
ok( $g->has_vertex('c'));
ok(!$g->has_vertex('d'));
$g->set_vertex_attribute('b','a',1);
ok( $g->delete_vertex('b'));
ok( $g->has_vertex('a'));
ok(!$g->has_vertex('b'));
ok( $g->has_vertex('c'));
ok(!$g->has_vertex('d'));
ok( $g->delete_vertex('a'));
ok(!$g->has_vertex('a'));
ok(!$g->has_vertex('b'));
ok( $g->has_vertex('c'));
ok(!$g->has_vertex('d'));