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from itertools import chain
import pytest
import networkx as nx
class TestIsSemiconnected:
def test_undirected(self):
pytest.raises(nx.NetworkXNotImplemented, nx.is_semiconnected, nx.Graph())
pytest.raises(nx.NetworkXNotImplemented, nx.is_semiconnected, nx.MultiGraph())
def test_empty(self):
pytest.raises(nx.NetworkXPointlessConcept, nx.is_semiconnected, nx.DiGraph())
pytest.raises(
nx.NetworkXPointlessConcept, nx.is_semiconnected, nx.MultiDiGraph()
)
def test_single_node_graph(self):
G = nx.DiGraph()
G.add_node(0)
assert nx.is_semiconnected(G)
def test_path(self):
G = nx.path_graph(100, create_using=nx.DiGraph())
assert nx.is_semiconnected(G)
G.add_edge(100, 99)
assert not nx.is_semiconnected(G)
def test_cycle(self):
G = nx.cycle_graph(100, create_using=nx.DiGraph())
assert nx.is_semiconnected(G)
G = nx.path_graph(100, create_using=nx.DiGraph())
G.add_edge(0, 99)
assert nx.is_semiconnected(G)
def test_tree(self):
G = nx.DiGraph()
G.add_edges_from(
chain.from_iterable([(i, 2 * i + 1), (i, 2 * i + 2)] for i in range(100))
)
assert not nx.is_semiconnected(G)
def test_dumbbell(self):
G = nx.cycle_graph(100, create_using=nx.DiGraph())
G.add_edges_from((i + 100, (i + 1) % 100 + 100) for i in range(100))
assert not nx.is_semiconnected(G) # G is disconnected.
G.add_edge(100, 99)
assert nx.is_semiconnected(G)
def test_alternating_path(self):
G = nx.DiGraph(
chain.from_iterable([(i, i - 1), (i, i + 1)] for i in range(0, 100, 2))
)
assert not nx.is_semiconnected(G)
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