def test_breadth_first_3_el():
graph = Graph()
start = graph.add_node('spam')
middle = graph.add_node('bacon')
end = graph.add_node('eggs')
graph.add_edge(start, end)
graph.add_edge(start, middle, 2)
assert graph.breadth_first(start) == ['spam', 'eggs', 'bacon']
def test_breadth_first_few_edges():
graph = Graph()
first = graph.add_node('spam')
second = graph.add_node('bacon')
third = graph.add_node('eggs')
fourth = graph.add_node('butter')
graph.add_edge(first, second)
graph.add_edge(first, third, 2)
graph.add_edge(second, third, 3)
graph.add_edge(third, fourth, 4)
assert graph.breadth_first(first) == ['spam', 'bacon', 'eggs', 'butter']
def test_breadth_1_edge():
graph = Graph()
first = graph.add_node('spam')
second = graph.add_node('bacon')
graph.add_edge(first, second)
assert graph.breadth_first(first) == ['spam', 'bacon']