Properly test different access type return values.

Augment test_pdo_getitem() to not only check the mapped object values.
What's more important is the type of object returned, and whether it
is the correct object (identical to other access method results).

Author: acolomb

test/test_pdo.py

@@ -50,15 +50,25 @@ def test_pdo_getitem(self):
         self.assertEqual(node.tpdo[1]['BOOLEAN value 2'].raw, True)
 
         # Test different types of access
-        self.assertEqual(node.pdo[0x1600]['INTEGER16 value'].raw, -3)
-        self.assertEqual(node.pdo['INTEGER16 value'].raw, -3)
-        self.assertEqual(node.pdo.tx[1]['INTEGER16 value'].raw, -3)
-        self.assertEqual(node.pdo[0x2001].raw, -3)
-        self.assertEqual(node.tpdo[0x2001].raw, -3)
-        self.assertEqual(node.pdo[0x2002].raw, 0xf)
-        self.assertEqual(node.pdo['0x2002'].raw, 0xf)
-        self.assertEqual(node.tpdo[0x2002].raw, 0xf)
-        self.assertEqual(node.pdo[0x1600][0x2002].raw, 0xf)
+        by_mapping_record = node.pdo[0x1600]
+        self.assertIsInstance(by_mapping_record, canopen.pdo.PdoMap)
+        self.assertEqual(by_mapping_record['INTEGER16 value'].raw, -3)
+        by_object_name = node.pdo['INTEGER16 value']
+        self.assertIsInstance(by_object_name, canopen.pdo.PdoVariable)
+        self.assertIs(by_object_name.od, node.object_dictionary['INTEGER16 value'])
+        self.assertEqual(by_object_name.raw, -3)
+        by_pdo_index = node.pdo.tx[1]
+        self.assertIs(by_pdo_index, by_mapping_record)
+        by_object_index = node.pdo[0x2001]
+        self.assertIsInstance(by_object_index, canopen.pdo.PdoVariable)
+        self.assertIs(by_object_index, by_object_name)
+        by_object_index_tpdo = node.tpdo[0x2001]
+        self.assertIs(by_object_index_tpdo, by_object_name)
+        by_object_index = node.pdo[0x2002]
+        self.assertEqual(by_object_index.raw, 0xf)
+        self.assertIs(node.pdo['0x2002'], by_object_index)
+        self.assertIs(node.tpdo[0x2002], by_object_index)
+        self.assertIs(node.pdo[0x1600][0x2002], by_object_index)
 
     def test_pdo_save(self):
         self.node.tpdo.save()