158 lines
3.9 KiB
Python
158 lines
3.9 KiB
Python
import pytest
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import networkx as nx
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class TestTreeRecognition(object):
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graph = nx.Graph
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multigraph = nx.MultiGraph
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@classmethod
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def setup_class(cls):
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cls.T1 = cls.graph()
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cls.T2 = cls.graph()
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cls.T2.add_node(1)
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cls.T3 = cls.graph()
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cls.T3.add_nodes_from(range(5))
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edges = [(i, i + 1) for i in range(4)]
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cls.T3.add_edges_from(edges)
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cls.T5 = cls.multigraph()
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cls.T5.add_nodes_from(range(5))
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edges = [(i, i + 1) for i in range(4)]
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cls.T5.add_edges_from(edges)
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cls.T6 = cls.graph()
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cls.T6.add_nodes_from([6, 7])
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cls.T6.add_edge(6, 7)
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cls.F1 = nx.compose(cls.T6, cls.T3)
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cls.N4 = cls.graph()
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cls.N4.add_node(1)
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cls.N4.add_edge(1, 1)
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cls.N5 = cls.graph()
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cls.N5.add_nodes_from(range(5))
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cls.N6 = cls.graph()
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cls.N6.add_nodes_from(range(3))
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cls.N6.add_edges_from([(0, 1), (1, 2), (2, 0)])
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cls.NF1 = nx.compose(cls.T6, cls.N6)
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def test_null_tree(self):
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with pytest.raises(nx.NetworkXPointlessConcept):
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nx.is_tree(self.graph())
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nx.is_tree(self.multigraph())
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def test_null_forest(self):
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with pytest.raises(nx.NetworkXPointlessConcept):
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nx.is_forest(self.graph())
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nx.is_forest(self.multigraph())
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def test_is_tree(self):
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assert nx.is_tree(self.T2)
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assert nx.is_tree(self.T3)
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assert nx.is_tree(self.T5)
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def test_is_not_tree(self):
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assert not nx.is_tree(self.N4)
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assert not nx.is_tree(self.N5)
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assert not nx.is_tree(self.N6)
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def test_is_forest(self):
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assert nx.is_forest(self.T2)
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assert nx.is_forest(self.T3)
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assert nx.is_forest(self.T5)
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assert nx.is_forest(self.F1)
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assert nx.is_forest(self.N5)
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def test_is_not_forest(self):
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assert not nx.is_forest(self.N4)
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assert not nx.is_forest(self.N6)
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assert not nx.is_forest(self.NF1)
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class TestDirectedTreeRecognition(TestTreeRecognition):
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graph = nx.DiGraph
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multigraph = nx.MultiDiGraph
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def test_disconnected_graph():
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# https://github.com/networkx/networkx/issues/1144
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G = nx.Graph()
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G.add_edges_from([(0, 1), (1, 2), (2, 0), (3, 4)])
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assert not nx.is_tree(G)
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G = nx.DiGraph()
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G.add_edges_from([(0, 1), (1, 2), (2, 0), (3, 4)])
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assert not nx.is_tree(G)
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def test_dag_nontree():
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G = nx.DiGraph()
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G.add_edges_from([(0, 1), (0, 2), (1, 2)])
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assert not nx.is_tree(G)
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assert nx.is_directed_acyclic_graph(G)
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def test_multicycle():
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G = nx.MultiDiGraph()
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G.add_edges_from([(0, 1), (0, 1)])
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assert not nx.is_tree(G)
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assert nx.is_directed_acyclic_graph(G)
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def test_emptybranch():
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G = nx.DiGraph()
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G.add_nodes_from(range(10))
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assert nx.is_branching(G)
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assert not nx.is_arborescence(G)
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def test_path():
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G = nx.DiGraph()
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nx.add_path(G, range(5))
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assert nx.is_branching(G)
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assert nx.is_arborescence(G)
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def test_notbranching1():
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# Acyclic violation.
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G = nx.MultiDiGraph()
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G.add_nodes_from(range(10))
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G.add_edges_from([(0, 1), (1, 0)])
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assert not nx.is_branching(G)
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assert not nx.is_arborescence(G)
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def test_notbranching2():
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# In-degree violation.
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G = nx.MultiDiGraph()
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G.add_nodes_from(range(10))
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G.add_edges_from([(0, 1), (0, 2), (3, 2)])
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assert not nx.is_branching(G)
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assert not nx.is_arborescence(G)
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def test_notarborescence1():
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# Not an arborescence due to not spanning.
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G = nx.MultiDiGraph()
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G.add_nodes_from(range(10))
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G.add_edges_from([(0, 1), (0, 2), (1, 3), (5, 6)])
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assert nx.is_branching(G)
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assert not nx.is_arborescence(G)
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def test_notarborescence2():
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# Not an arborescence due to in-degree violation.
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G = nx.MultiDiGraph()
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nx.add_path(G, range(5))
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G.add_edge(6, 4)
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assert not nx.is_branching(G)
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assert not nx.is_arborescence(G)
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