"""
    Unit tests for yaml.
"""

import os,tempfile
from nose import SkipTest
from nose.tools import assert_equal

import networkx as nx
from networkx.testing import assert_edges_equal, assert_nodes_equal

class TestYaml(object):
    @classmethod
    def setupClass(cls):
        global yaml
        try:
            import yaml
        except ImportError:
            raise SkipTest('yaml not available.')

    def setUp(self):
        self.build_graphs()

    def build_graphs(self):
        self.G = nx.Graph(name="test")
        e = [('a','b'),('b','c'),('c','d'),('d','e'),('e','f'),('a','f')]
        self.G.add_edges_from(e)
        self.G.add_node('g')

        self.DG = nx.DiGraph(self.G)

        self.MG = nx.MultiGraph()
        self.MG.add_weighted_edges_from([(1,2,5),(1,2,5),(1,2,1),(3,3,42)])

    def assert_equal(self, G, data=False):
        (fd, fname) = tempfile.mkstemp()
        nx.write_yaml(G, fname)
        Gin = nx.read_yaml(fname)

        assert_nodes_equal(list(G), list(Gin))
        assert_edges_equal(G.edges(data=data), Gin.edges(data=data))

        os.close(fd)
        os.unlink(fname)
   
    def testUndirected(self):
        self.assert_equal(self.G, data=False)

    def testDirected(self):
        self.assert_equal(self.DG, data=False)

    def testMultiGraph(self):
        self.assert_equal(self.MG, data=True)