class TestKnots(unittest.TestCase):
def setUp(self):
self.v = Vertex('v')
self.w = Vertex('w')
self.x = Vertex('x')
self.e1 = Arc(self.v, self.w)
self.e2 = Arc(self.w, self.x)
self.e3 = Arc(self.x, self.v)
self.dg = DirectedGraph([self.v, self.w, self.x],
[self.e1, self.e2, self.e3])
def test_positive(self):
#triangular knot
self.assertEqual(self.dg.has_knot(), True)
#triangular knot w/ an edge into it
self.a = Vertex('a')
self.dg.add_vertex(self.a)
self.Kanye = Arc(self.a,self.v)
self.dg.add_edge(self.Kanye)
self.assertTrue(self.dg.has_knot())
def test_ngon_with_chord(self):
v1 = Vertex('v1')
v2 = Vertex('v2')
v3 = Vertex('v3')
v4 = Vertex('v4')
v5 = Vertex('v5')
e1 = Arc(v2,v1)
e2 = Arc(v3,v2)
e3 = Arc(v3,v4)
e4 = Arc(v4,v5)
e5 = Arc(v5,v1)
ngon = DirectedGraph([v1,v2,v3,v4,v5],
[e1,e2,e3,e4,e5])
self.assertFalse(ngon.has_knot())
chord = Arc(v1,v4)
ngon.add_edge(chord)
self.assertTrue(ngon.has_knot())
def test_ngon_with_chord(self):
v1 = Vertex('v1')
v2 = Vertex('v2')
v3 = Vertex('v3')
v4 = Vertex('v4')
v5 = Vertex('v5')
e1 = Arc(v2,v1)
e2 = Arc(v3,v2)
e3 = Arc(v3,v4)
e4 = Arc(v4,v5)
e5 = Arc(v5,v1)
ngon = DirectedGraph([v1,v2,v3,v4,v5],
[e1,e2,e3,e4,e5])
self.assertFalse(ngon.has_knot())
chord = Arc(v1,v4)
ngon.add_edge(chord)
self.assertTrue(ngon.has_knot())