#define BOOST_TEST_MODULE graph

#include <boost/graph/undirected_graph.hpp>
#include <boost/test/unit_test.hpp>

typedef boost::undirected_graph<> Graph;
typedef Graph::edge_descriptor Edge;
typedef Graph::vertex_descriptor Vertex;

BOOST_AUTO_TEST_CASE(undirected_edge_test)
{
  Graph g(2);
  Vertex a = *(vertices(g).first);
  Vertex b = *(++vertices(g).first);
  Edge e1, e2;
  bool r1, r2;

  // Create the edge.  This is an undirected edge.
  add_edge(a, b, g);

  tie(e1, r1) = boost::edge(a, b, g);
  tie(e2, r2) = boost::edge(b, a, g);
  BOOST_CHECK(r1);
  BOOST_CHECK(r2);
  BOOST_CHECK(num_edges(g) == 1);
  // Edges e1 and e2 are the same.
  BOOST_CHECK(e1 == e2);
  // Yet, BGL can tell what the source and target nodes are are, and
  // they are different for e1 and e2.
  BOOST_CHECK(boost::source(e1, g) == a);
  BOOST_CHECK(boost::target(e1, g) == b);
  BOOST_CHECK(boost::source(e2, g) == b);
  BOOST_CHECK(boost::target(e2, g) == a);
}