fix(undulator_mode): rely on new base class to resolve done

tests/tests_devices/test_undulator.py

@@ -61,6 +61,7 @@ def test_set_accepts_every_mode(mode, selected, input_type):
     index = list(UndulatorModeEnum).index(selected)
     target = {"label": selected.value, "enum": selected, "index": index}[input_type]
 
+    mode.setpoint._read_pv.mock_data = (index + 1) % len(UndulatorModeEnum)
     status = mode.set(target)
 
     assert mode.setpoint.get() == index
@@ -68,10 +69,8 @@ def test_set_accepts_every_mode(mode, selected, input_type):
     finish_move(mode, status)
 
 
-@pytest.mark.parametrize("busy", [False, True])
-def test_same_mode_still_writes_and_waits_for_done(mode, busy):
-    if busy:
-        mode.done._read_pv.mock_data = 0
+def test_same_mode_while_busy_still_writes_and_waits_for_done(mode):
+    mode.done._read_pv.mock_data = 0
     with patch.object(mode.setpoint, "put", wraps=mode.setpoint.put) as put:
         status = mode.set("Off")
 
@@ -80,6 +79,20 @@ def test_same_mode_still_writes_and_waits_for_done(mode, busy):
     finish_move(mode, status)
 
 
+@pytest.mark.parametrize("target", ["Circular+", UndulatorModeEnum.CIRCULAR_PLUS, 4])
+@pytest.mark.parametrize("method", ["set", "move"])
+def test_idle_same_mode_completes_without_write(mode, target, method):
+    mode.setpoint._read_pv.mock_data = 4
+    with patch.object(mode.setpoint, "put") as put:
+        status = getattr(mode, method)(target, timeout=1)
+        status.wait(timeout=1)
+
+    put.assert_not_called()
+    assert status.done
+    assert status.success
+    assert status.target == 4
+
+
 def test_move_normalizes_labels_and_preserves_callback_and_timeout(mode):
     moved_cb = Mock()
     status = mode.move("Circular+", wait=False, timeout=1, moved_cb=moved_cb)

xtreme_bec/devices/undulator.py

@@ -65,9 +65,9 @@ class UndulatorMode(_CMUOnlineMixin, UndulatorBase):
     """X-Treme undulator polarization positioner, completed by the IOC's DONE signal.
 
     The CMU must be On-line and control must belong to the beamline.
-    Use ``set("Circular+")`` or ``set(4)`` to select a mode. As with harmonic
-    and alpha control, every request writes the target and waits for DONE,
-    including requests for the currently selected mode.
+    Use ``set("Circular+")`` or ``set(4)`` to select a mode. Requests for the
+    currently selected mode complete without writing when the undulator is idle.
+    All other requests write the target and wait for DONE.
     """
 
     control_validations = UndulatorBase.control_validations + _CMU_ONLINE_VALIDATIONS
@@ -103,7 +103,7 @@ class UndulatorMode(_CMUOnlineMixin, UndulatorBase):
     ) -> StatusBase:
         """Select a mode by label or index and wait for undulator completion.
 
-        ``set()`` delegates here with ``wait=False`` and returns a pending status.
+        ``set()`` delegates here with ``wait=False`` and returns a status.
         Invalid labels and indices raise ValueError before issuing a command.
         """
         modes = list(UndulatorModeEnum)
@@ -124,5 +124,4 @@ class UndulatorMode(_CMUOnlineMixin, UndulatorBase):
         else:
             raise TypeError("Mode must be either a string or an integer index.")
 
-        self.validate_control()
         return super().move(mode, wait=wait, timeout=timeout, moved_cb=moved_cb)