Save the passed node ID to the resulting OD in import_od() (#484)

Only for DCF-files (which include a DeviceComissioning section), the Node-ID from the file is stored in the ObjectDictionary instance.  When given an override value via the `import_od(..., node_id=...)` argument, that was however not applied to the OD attribute, but only used for $NODEID interpolation.

Make sure the interpolated values match the stored node_id in this case.

Also handle a missing NodeID option within the DeviceComissioning section gracefully, instead of raising an exception.

canopen/objectdictionary/eds.py

@@ -86,8 +86,11 @@ def import_eds(source, node_id):
 
     if eds.has_section("DeviceComissioning"):
         od.bitrate = int(eds.get("DeviceComissioning", "Baudrate")) * 1000
-        od.node_id = int(eds.get("DeviceComissioning", "NodeID"), 0)
-        node_id = node_id or od.node_id
+
+        if node_id is None:
+            if val := eds.get("DeviceComissioning", "NodeID", fallback=None):
+                node_id = int(val, base=0)
+        od.node_id = node_id
 
     for section in eds.sections():
         # Match dummy definitions

test/sample.eds

@@ -30,7 +30,7 @@ NrOfTXPDO=4
 LSS_Supported=0
 
 [DeviceComissioning]
-NodeID=2
+NodeID=0x10
 NodeName=Some name
 Baudrate=500
 NetNumber=0

test/test_eds.py

@@ -4,7 +4,9 @@
 from canopen.objectdictionary.eds import _signed_int_from_hex
 from canopen.utils import pretty_index
 
-EDS_PATH = os.path.join(os.path.dirname(__file__), 'sample.eds')
+
+SAMPLE_EDS = os.path.join(os.path.dirname(__file__), 'sample.eds')
+DATATYPES_EDS = os.path.join(os.path.dirname(__file__), 'datatypes.eds')
 
 
 class TestEDS(unittest.TestCase):
@@ -48,7 +50,7 @@ class TestEDS(unittest.TestCase):
     }
 
     def setUp(self):
-        self.od = canopen.import_od(EDS_PATH, 2)
+        self.od = canopen.import_od(SAMPLE_EDS, 2)
 
     def test_load_nonexisting_file(self):
         with self.assertRaises(IOError):
@@ -59,10 +61,34 @@ def test_load_unsupported_format(self):
             canopen.import_od(__file__)
 
     def test_load_file_object(self):
-        with open(EDS_PATH) as fp:
+        with open(SAMPLE_EDS) as fp:
             od = canopen.import_od(fp)
         self.assertTrue(len(od) > 0)
 
+    def test_load_implicit_nodeid(self):
+        # sample.eds has a DeviceComissioning section with NodeID set to 0x10.
+        od = canopen.import_od(SAMPLE_EDS)
+        self.assertEqual(od.node_id, 16)
+
+    def test_load_implicit_nodeid_fallback(self):
+        import io
+
+        # First, remove the NodeID option from DeviceComissioning.
+        with open(SAMPLE_EDS) as f:
+            lines = [L for L in f.readlines() if not L.startswith("NodeID=")]
+        with io.StringIO("".join(lines)) as buf:
+            buf.name = "mock.eds"
+            od = canopen.import_od(buf)
+            self.assertIsNone(od.node_id)
+
+        # Next, try an EDS file without a DeviceComissioning section.
+        od = canopen.import_od(DATATYPES_EDS)
+        self.assertIsNone(od.node_id)
+
+    def test_load_explicit_nodeid(self):
+        od = canopen.import_od(SAMPLE_EDS, node_id=3)
+        self.assertEqual(od.node_id, 3)
+
     def test_variable(self):
         var = self.od['Producer heartbeat time']
         self.assertIsInstance(var, canopen.objectdictionary.ODVariable)