def test_undirected_vertex_has_self_edge(self):
""" Get an undirected vertex's has_self_edge property """
v0 = UndirectedVertex(val='v0')
v1 = UndirectedVertex(val='v1')
v2 = UndirectedVertex(val='v2')
e00 = UndirectedEdge((v0, v0))
e01 = UndirectedEdge((v0, v1))
e11 = UndirectedEdge((v1, v1))
e02 = UndirectedEdge((v0, v2))
v0.add_edge(e00)
v0.add_edge(e01)
v1.add_edge(e01)
v0.add_edge(e02)
v2.add_edge(e02)
self.assertTrue(v0.has_self_edge)
self.assertFalse(v1.has_self_edge)
self.assertFalse(v2.has_self_edge)
with self.assertRaises(AttributeError):
v0.has_self_edge = True
v1.add_edge(e11)
v0.remove_edge(e00)
self.assertFalse(v0.has_self_edge)
self.assertTrue(v1.has_self_edge)
self.assertFalse(v2.has_self_edge)
def test_undirected_vertex_not_part_of_edge(self):
""" An undirected vertex should not be able add an edge which doesn't
have it as a vertex """
v0 = UndirectedVertex(val='v0')
v1 = UndirectedVertex(val='v1')
v2 = UndirectedVertex(val='v2')
e12 = UndirectedEdge((v1, v2))
with self.assertRaises(ValueError):
v0.add_edge(e12)
def test_undirected_vertex_add_edge(self):
""" Add an edge to an undirected vertex """
v0 = UndirectedVertex(val='v0')
v1 = UndirectedVertex(val='v1')
v2 = UndirectedVertex(val='v2')
e00 = UndirectedEdge((v0, v0))
e01 = UndirectedEdge((v0, v1))
e10 = UndirectedEdge((v1, v0))
e02 = UndirectedEdge((v0, v2))
v0.add_edge(e00)
v0.add_edge(e01)
self.assertTrue(e00 in v0)
self.assertTrue(e01 in v0)
self.assertTrue(e10 in v0)
self.assertFalse(e02 in v0)
def test_undirected_vertex_neighbors_and_degree(self):
""" Get undirected vertices' neighbors and degree properties """
v0 = UndirectedVertex(val='v0')
v1 = UndirectedVertex(val='v1')
v2 = UndirectedVertex(val='v2')
e00 = UndirectedEdge((v0, v0))
e01 = UndirectedEdge((v0, v1))
e02 = UndirectedEdge((v0, v2))
v0.add_edge(e01)
v0.add_edge(e02)
self.assertEqual(set(v0.neighbors), set([v1, v2]))
with self.assertRaises(AttributeError):
v0.neighbors = set()
self.assertEqual(v0.degree, 2)
with self.assertRaises(AttributeError):
v0.degree = 0
v0.add_edge(e00)
self.assertEqual(set(v0.neighbors), set([v0, v1, v2]))
self.assertEqual(v0.degree, 4)
def test_undirected_vertex_remove_edge(self):
""" Remove an edge from an undirected vertex """
v0 = UndirectedVertex(val='v0')
v1 = UndirectedVertex(val='v1')
v2 = UndirectedVertex(val='v2')
e01 = UndirectedEdge((v0, v1))
e10 = UndirectedEdge((v1, v0))
e02 = UndirectedEdge((v0, v2))
v0.add_edge(e01)
v0.add_edge(e02)
v0.remove_edge(e01)
self.assertFalse(e01 in v0)
self.assertFalse(e10 in v0)
self.assertTrue(e02 in v0)
v0.remove_edge(e02)
self.assertFalse(e01 in v0)
self.assertFalse(e10 in v0)
self.assertFalse(e02 in v0)
def test_undirected_vertex_edges(self):
""" Get an undirected vertex's edges property """
v0 = UndirectedVertex(val='v0')
v1 = UndirectedVertex(val='v1')
v2 = UndirectedVertex(val='v2')
e00 = UndirectedEdge((v0, v0))
e01 = UndirectedEdge((v0, v1))
e02 = UndirectedEdge((v0, v2))
v0.add_edge(e00)
v0.add_edge(e01)
v1.add_edge(e01)
v0.add_edge(e02)
v2.add_edge(e02)
self.assertEqual(set(v0.edges), set([e00, e01, e02]))
self.assertEqual(set(v1.edges), set([e01]))
self.assertEqual(set(v2.edges), set([e02]))
with self.assertRaises(AttributeError):
v0.edges = set()
def test_undirected_vertex_already_has_edge(self):
""" An undirected vertex should not be able to add an edge that it
already has """
v0 = UndirectedVertex(val='v0')
v1 = UndirectedVertex(val='v1')
e01 = UndirectedEdge((v0, v1))
v0.add_edge(e01)
with self.assertRaises(ValueError):
v0.add_edge(e01)
try:
v1.add_edge(e01)
except ValueError:
self.fail("Adding the edge (v0, v1) to v0 should not stop the edge "
"(v0, v1) from being added to v1.")
