Merge pull request networkx#1829 from SanketDG/reciprocity

add tests for networkx.algorithms.reciprocity

networkx/algorithms/tests/test_reciprocity.py

@@ -0,0 +1,37 @@
+from nose.tools import *
+import networkx as nx
+
+
+class TestReciprocity(object):
+
+    # test overall reicprocity by passing whole graph
+    def test_reciprocity_digraph(self):
+        DG = nx.DiGraph([(1, 2), (2, 1)])
+        reciprocity = nx.reciprocity(DG)
+        assert reciprocity == 1.0
+
+    # test empty graph's overall reciprocity which will throw an error
+    @raises(nx.NetworkXError)
+    def test_overall_reciprocity_empty_graph(self):
+        DG = nx.DiGraph()
+        nx.overall_reciprocity(DG)
+
+    # test for reciprocity for a list of nodes
+    def test_reciprocity_graph_nodes(self):
+        DG = nx.DiGraph([(1, 2), (2, 3), (3, 2)])
+        reciprocity = nx.reciprocity(DG, [1, 2])
+        expected_reciprocity = {1: 0.0, 2: 0.6666666666666666}
+        assert reciprocity == expected_reciprocity
+
+    # test for reciprocity for a single node
+    def test_reciprocity_graph_node(self):
+        DG = nx.DiGraph([(1, 2), (2, 3), (3, 2)])
+        reciprocity = nx.reciprocity(DG, 2)
+        assert reciprocity == 0.6666666666666666
+
+    # test for reciprocity for an isolated node
+    @raises(nx.NetworkXError)
+    def test_reciprocity_graph_isolated_nodes(self):
+        DG = nx.DiGraph([(1, 2)])
+        DG.add_node(4)
+        nx.reciprocity(DG, 4)