Updated handling of duplicate devices.

Previously, the old device would be retained and the new device would
be ignored. Now, the new device overwrites the old device.

Also, the warning for a duplicate name is only issued for the top
level devices in the device hierarchy.

src/ophydregistry/registry.py

@@ -519,7 +519,7 @@ def __new__wrapper(self, cls, *args, **kwargs):
         return obj
 
     def register(
-        self, component: ophydobj.OphydObject, labels: Optional[Sequence] = None
+            self, component: ophydobj.OphydObject, labels: Optional[Sequence] = None, warn_duplicates=True
     ) -> ophydobj.OphydObject:
         """Register a device, component, etc so that it can be retrieved later.
 
@@ -534,6 +534,9 @@ def register(
         labels
           Device labels to use for registration. If `None` (default),
           the devices *_ophyd_labels_* parameter will be used.
+        warn_duplicates
+          If true, a warning will be issued if this device is
+          overwriting a previous device with the same name.
 
         """
         # Determine how to register the device
@@ -552,7 +555,8 @@ def register(
             # Ignore any instances with the same name as a previous component
             # (Needed for some sub-components that are just readback
             # values of the parent)
-            # Check that we're not adding a duplicate component name
+            # Check if we're adding a duplicate component name
+            is_duplicate = False
             if name in self._objects_by_name.keys():
                 old_obj = self._objects_by_name[name]
                 is_readback = component in [
@@ -563,11 +567,15 @@ def register(
                 if is_readback:
                     msg = f"Ignoring readback with duplicate name: '{name}'"
                     log.debug(msg)
+                    return component
                 else:
                     msg = f"Ignoring component with duplicate name: '{name}'"
-                    log.warning(msg)
-                    warnings.warn(msg)
-                return component
+                    is_duplicate = True
+                    if warn_duplicates:
+                        log.warning(msg)
+                        warnings.warn(msg)
+                    else:
+                        log.debug(msg)
             # Register this component
             log.debug(f"Registering {name}")
             # Create a set for this device name if it doesn't exist
@@ -599,5 +607,5 @@ def register(
             else:
                 sub_signals = []
             for cpt_name, cpt in sub_signals:
-                self.register(cpt)
+                self.register(cpt, warn_duplicates=not is_duplicate and warn_duplicates)
         return component

src/ophydregistry/tests/test_instrument_registry.py

@@ -390,21 +390,28 @@ def test_getitem(registry):
 
 def test_duplicate_device(caplog, registry):
     """Check that a device doesn't get added twice."""
-    motor = sim.motor
+    # Two devices with the same name
+    motor1 = sim.instantiate_fake_device(EpicsMotor, prefix="", name="motor")
+    motor2 = sim.instantiate_fake_device(EpicsMotor, prefix="", name="motor")
     # Set up logging so that we can know what
     caplog.clear()
     with caplog.at_level(logging.DEBUG):
-        registry.register(motor)
+        registry.register(motor1)
     # Check for the edge case where motor and motor.user_readback have the same name
     assert "Ignoring component with duplicate name" not in caplog.text
     assert "Ignoring readback with duplicate name" in caplog.text
     # Check that truly duplicated entries get a warning
     caplog.clear()
     with caplog.at_level(logging.WARNING):
         with pytest.warns(UserWarning):
-            registry.register(motor)
+            registry.register(motor2)
     # Check for the edge case where motor and motor.user_readback have the same name
     assert "Ignoring component with duplicate name" in caplog.text
+    print(caplog.text)
+    # Check that the warning is only issued for the top-level device, not all its children
+    assert "motor_user_setpoint" not in caplog.text
+    # Check that the correct second device is the one that wound up in the registry
+    assert registry['motor'] is motor2
 
 
 def test_delete_by_name(registry):
@@ -472,7 +479,7 @@ def test_weak_references():
 
     """
     motor = sim.SynAxis(name="weak_motor", labels={"motors"})
-    registry = Registry(keep_references=False)
+    registry = Registry(keep_references=False, auto_register=False)
     registry.register(motor)
     # Can we still find the object if the test has a reference?
     assert registry.find("weak_motor") is motor