use Test::More tests => 5;
use Graph;
my $g = Graph->new;
ok( $g->add_edge("a", "b") );
ok( $g->add_edge("b", "c") );
is( $g->add_edge("c", "d"), $g );
eval '$g->add_edge("c", "d", "e", "f")';
like($@,
qr/Graph::add_edge: graph is not hyperedged/);
eval '$g->add_edge("c")';
like($@,
qr/Graph::add_edge: graph is not hyperedged/);