def test_add_marked_arrows():
graph = MarkedPatternGraph(nodes=['a', 'b'], undirected_edges=[('a', 'b')])
graph.add_marked_arrow(('c', 'd'))
assert graph.get_marked_arrows() == set({('c', 'd')})
assert set(graph.get_edges()) == set(
{frozenset({'a', 'b'}), frozenset({'c', 'd'})})
def test_remove_undirected_edge_when_not_exist():
graph = MarkedPatternGraph(nodes=['a', 'b'])
graph.remove_undirected_edge(('a', 'b'))
assert set(graph.get_undirected_edges()) == set({})
assert set(graph.get_unmarked_arrows()) == set({})
assert set(graph.get_marked_arrows()) == set({})
assert set(graph.get_bidirectional_edges()) == set({})
assert set(graph.get_edges()) == set({})
def test_add_marked_arrowhead():
graph = MarkedPatternGraph(nodes=['a', 'b'])
graph.add_undirected_edge(('a', 'b'))
graph.add_marked_arrowhead(('a', 'b'))
assert set(graph.get_undirected_edges()) == set({})
assert set(graph.get_unmarked_arrows()) == set({})
assert set(graph.get_marked_arrows()) == set({('a', 'b')})
assert set(graph.get_bidirectional_edges()) == set({})
assert set(graph.get_edges()) == set({frozenset({'a', 'b'})})
def test_simple():
# a c
# \ /
# v v
# b
# |
# d
graph = MarkedPatternGraph(nodes=['a', 'b', 'c', 'd'])
graph.add_undirected_edge(('a', 'b'))
graph.add_undirected_edge(('c', 'b'))
graph.add_undirected_edge(('b', 'd'))
graph.add_arrowhead(('a', 'b'))
graph.add_arrowhead(('c', 'b'))
assert graph.get_edges() == set(
{frozenset({'a', 'b'}),
frozenset({'b', 'c'}),
frozenset({'b', 'd'})})
