public void HashCodeTest()
{
Vertex v = new Vertex();
Vertex g = new Vertex();
Edge eVV = new Edge(v, v);
Edge eVG = new Edge(v, g);
Assert.IsTrue(eVV.GetHashCode() == eVV.GetHashCode());
Assert.IsTrue(eVG.GetHashCode() == new Edge(v, g).GetHashCode());
}