Added additional Graph selection test

tests/testgraphelement.py

@@ -40,8 +40,9 @@ def test_constructor_with_nodes_and_paths_dimension_mismatch(self):
 
     def test_select_by_node(self):
         graph = Graph(((self.source, self.target),))
-        selection = Graph(([(0,0), (1, 0)], list(zip(*self.nodes))[:2]))
-        self.assertEqual(graph.select(index=(0, 2)), selection) 
+        selection = Graph(([(1, 0), (2, 0)], list(zip(*self.nodes))[0:3]))
+        print(graph.select(index=(1, 3)).data)
+        self.assertEqual(graph.select(index=(1, 3)), selection) 
 
     def test_select_by_source(self):
         graph = Graph(((self.source, self.target),))
@@ -53,6 +54,11 @@ def test_select_by_target(self):
         selection = Graph(([(0,0), (1, 0)], list(zip(*self.nodes))[:2]))
         self.assertEqual(graph.select(start=(0, 2)), selection)
 
+    def test_select_by_source_and_target(self):
+        graph = Graph(((self.source, self.source+1), self.nodes))
+        selection = Graph(([(0,1)], list(zip(*self.nodes))[:2]))
+        self.assertEqual(graph.select(start=(0, 3), end=1), selection)
+
     def test_select_by_edge_data(self):
         graph = Graph(((self.target, self.source, self.edge_info),), vdims=['info'])
         selection = Graph(([(0, 0, 0), (0, 1, 1)], list(zip(*self.nodes))[:2]), vdims=['info'])