def test_converge(self):
e1 = Element()
e2 = Element()
e3 = Element()
e4 = Element()
e5 = Element()
e1.connect(e2, e3, e4)
ret = e1.converge(e5)
self.assertEqual(ret, e5)
self.assertEqual(e2.outgoing, [e5])
self.assertEqual(e3.outgoing, [e5])
self.assertEqual(e4.outgoing, [e5])
e6 = Element()
e7 = Element()
e8 = Element()
e9 = Element()
e10 = Element()
ret = e6.extend(e7).extend(e8).to(e6) \
.extend(e9).to(e6).converge(e10)
self.assertEqual(ret, e10)
self.assertEqual(e6.outgoing, [e7, e9])
self.assertEqual(e7.outgoing, [e8])
self.assertEqual(e8.outgoing, [e10])
self.assertEqual(e9.outgoing, [e10])
e11 = Element()
self.assertEqual(e11.tail(), e11)
def test_extend(self):
e1 = Element()
e2 = Element()
e3 = Element()
ret = e1.extend(e2).extend(e3)
self.assertEqual(ret, e3)
self.assertEqual(e1.outgoing, [e2])
self.assertEqual(e2.outgoing, [e3])
