Fix returned numbers in PDO.__iter__().

The base iterators of rx and tx return a 1-based sequence, while the
wrapping PDO class allows only mapping or communication record index
numbers to identify a PdoMap object.  Return the mapping record's
index from the iterator to avoid ambiguity.

Add tests to verify the returned objects are actually the RPDO and
TPDO members (in this order), with strictly increasing index numbers.

Author: acolomb

canopen/pdo/__init__.py

@@ -43,7 +43,10 @@ def __init__(self, node, rpdo: PdoBase, tpdo: PdoBase):
             self.map.maps[self.tx.com_offset + (key - 1)] = value
 
     def __iter__(self) -> Iterator[int]:
-        return itertools.chain(self.rx, self.tx)
+        return itertools.chain(
+            (self.rx.map_offset + i - 1 for i in self.rx),
+            (self.tx.map_offset + i - 1 for i in self.tx),
+        )
 
     def __len__(self) -> int:
         return len(self.rx) + len(self.tx)

test/test_pdo.py

@@ -79,6 +79,20 @@ def test_pdo_getitem(self):
         self.assertRaises(KeyError, lambda: node.pdo[0x1BFF])
         self.assertRaises(KeyError, lambda: node.tpdo[0x1BFF])
 
+    def test_pdo_iterate(self):
+        node = self.node
+        pdo_iter = iter(node.pdo.items())
+        prev = 0  # To check strictly increasing record index number
+        for rpdo, (index, pdo) in zip(node.rpdo.values(), pdo_iter):
+            self.assertIs(rpdo, pdo)
+            self.assertGreater(index, prev)
+            prev = index
+        # Continue consuming from pdo_iter
+        for tpdo, (index, pdo) in zip(node.tpdo.values(), pdo_iter):
+            self.assertIs(tpdo, pdo)
+            self.assertGreater(index, prev)
+            prev = index
+
     def test_pdo_maps_iterate(self):
         node = self.node
         self.assertEqual(len(node.pdo), sum(1 for _ in node.pdo))