import networkx as nx


def small_ego_G():
    """The sample network from https://arxiv.org/pdf/1310.6753v1.pdf"""
    edges = [('a', 'b'), ('a', 'c'), ('b', 'c'), ('b', 'd'),
             ('b', 'e'), ('b', 'f'), ('c', 'd'), ('c', 'f'), ('c', 'h'), ('d', 'f'), ('e', 'f'),
             ('f', 'h'), ('h', 'j'), ('h', 'k'), ('i', 'j'), ('i', 'k'), ('j', 'k'), ('u', 'a'),
             ('u', 'b'), ('u', 'c'), ('u', 'd'), ('u', 'e'), ('u', 'f'), ('u', 'g'), ('u', 'h'),
             ('u', 'i'), ('u', 'j'), ('u', 'k')]
    G = nx.Graph()
    G.add_edges_from(edges)

    return G


class TestDispersion(object):

    def test_article(self):
        """our algorithm matches article's"""
        G = small_ego_G()
        disp_uh = nx.dispersion(G, 'u', 'h', normalized=False)
        disp_ub = nx.dispersion(G, 'u', 'b', normalized=False)
        assert disp_uh == 4
        assert disp_ub == 1

    def test_results_length(self):
        """there is a result for every node"""
        G = small_ego_G()
        disp = nx.dispersion(G)
        disp_Gu = nx.dispersion(G, 'u')
        disp_uv = nx.dispersion(G, 'u', 'h')
        assert len(disp) == len(G)
        assert len(disp_Gu) == len(G) - 1
        assert type(disp_uv) is float

    def test_impossible_things(self):
        G = nx.karate_club_graph()
        disp = nx.dispersion(G)
        for u in disp:
            for v in disp[u]:
                assert disp[u][v] >= 0