def test_directed_path_graph(self):
"""Test a directed path graph with 10 nodes."""
graph = nx.path_graph(10).to_directed()
assert diameter(graph) == 9
def test_single_node(self):
"""Test a graph which contains just a node."""
graph = nx.Graph()
graph.add_node(1)
assert diameter(graph) == 0
def test_complete_directed_graph(self):
"""Test a complete directed graph."""
graph = nx.complete_graph(10, create_using=nx.DiGraph())
assert diameter(graph) == 1
def test_complete_undirected_graph(self):
"""Test a complete undirected graph."""
graph = nx.complete_graph(10)
assert diameter(graph) == 1
def test_directed_non_strongly_connected(self):
"""Test a directed non strongly connected graph."""
graph = nx.path_graph(10, create_using=nx.DiGraph())
with pytest.raises(nx.NetworkXError,
match="DiGraph not strongly connected."):
diameter(graph)
def test_undirected_non_connected(self):
"""Test an undirected disconnected graph."""
graph = nx.path_graph(10)
graph.remove_edge(3, 4)
with pytest.raises(nx.NetworkXError, match="Graph not connected."):
diameter(graph)
def test_null_graph(self):
"""Test empty graph."""
G = nx.null_graph()
with pytest.raises(nx.NetworkXError,
match="Expected non-empty NetworkX graph!"):
diameter(G)