Add test for undirected graph

Author: weilycoder

cyaron/graph.py

@@ -240,10 +240,7 @@ def edge_count(self):
         """edge_count(self) -> int
             Return the count of the edges in the graph.
         """
-        cnt = sum(len(node) for node in self.edges)
-        if not self.directed:
-            cnt //= 2
-        return cnt
+        return len(list(self.iterate_edges()))
 
     def to_matrix(self, **kwargs):
         """to_matrix(self, **kwargs) -> GraphMatrix

cyaron/tests/graph_test.py

@@ -225,3 +225,18 @@ def test_forest(self):
                 if dsu.get_father(i) == i:
                     count += 1
             self.assertEqual(count, part_count)
+
+    def test_from_undirected_degree_sequence(self):
+        get_deg_seq = lambda g: tuple(map(len, g.edges[1:]))
+        g1 = Graph.from_degree_sequence((2, 2, 1, 1, 1, 1))
+        self.assertEqual(get_deg_seq(g1), (2, 2, 1, 1, 1, 1))
+        for _ in range(8):
+            g0 = Graph.graph(
+                100, 400, directed=False, self_loop=False, repeated_edges=False
+            )
+            dsq = get_deg_seq(g0)
+            g1 = Graph.from_degree_sequence(dsq)
+        with self.assertRaises(ValueError):
+            Graph.from_degree_sequence((6, 6, 6))
+        with self.assertRaises(ValueError):
+            Graph.from_degree_sequence((1, 1, 1))