Add unique electrode id check

CHANGELOG.md

@@ -1,5 +1,10 @@
 # PyNWB Changelog
 
+## PyNWB 1.6.0 (TBD, 2021)
+
+## Bug fix:
+- Enforce electrode ID uniqueness during insertion into table
+
 ## PyNWB 1.5.1 (May 24, 2021)
 
 ## Bug fix:

src/pynwb/file.py

@@ -527,6 +527,8 @@ def add_electrode_column(self, **kwargs):
             {'name': 'rel_z', 'type': 'float', 'doc': 'the z coordinate within the electrode group', 'default': None},
             {'name': 'reference', 'type': str, 'doc': 'Description of the reference used for this electrode.',
              'default': None},
+            {'name': 'enforce_unique_id', 'type': bool, 'doc': 'enforce that the id in the table must be unique',
+             'default': True},
             allow_extra=True)
     def add_electrode(self, **kwargs):
         """

tests/integration/test_io.py

@@ -277,6 +277,16 @@ def test_append(self):
             errors = validate(io)
             self.assertTrue(len(errors) == 0)
 
+    def test_electrode_id_uniqueness(self):
+        device = self.nwbfile.create_device(name='test_device')
+        e_group = self.nwbfile.create_electrode_group(name='test_electrode_group',
+                                                      description='',
+                                                      location='',
+                                                      device=device)
+        self.nwbfile.add_electrode(id=0, x=0.0, y=0.0, z=0.0, imp=np.nan, location='', filtering='', group=e_group)
+        with self.assertRaises(ValueError):
+            self.nwbfile.add_electrode(id=0, x=0.0, y=0.0, z=0.0, imp=np.nan, location='', filtering='', group=e_group)
+
 
 class TestH5DataIO(TestCase):
     """