Set undulator gap after XBPM is stable

src/mx_bluesky/hyperion/experiment_plans/rotation_scan_plan.py

@@ -307,6 +307,10 @@ def _move_and_rotation(
     params: RotationScan,
     oav_params: OAVParameters,
 ):
+    if params.demand_energy_ev:
+        yield from bps.abs_set(
+            composite.undulator, params.demand_energy_ev / 1000, wait=True
+        )
     motor_time_to_speed = yield from bps.rd(composite.smargon.omega.acceleration_time)
     max_vel = yield from bps.rd(composite.smargon.omega.max_velocity)
     motion_values = calculate_motion_profile(params, motor_time_to_speed, max_vel)

tests/conftest.py

@@ -671,7 +671,7 @@ def fake_create_rotation_devices(
     xbpm_feedback: XBPMFeedback,
 ):
     set_mock_value(smargon.omega.max_velocity, 131)
-
+    undulator.set = MagicMock(return_value=NullStatus())
     return RotationScanComposite(
         attenuator=attenuator,
         backlight=backlight,

tests/unit_tests/hyperion/experiment_plans/test_rotation_scan_plan.py

@@ -706,6 +706,20 @@ def test_rotation_scan_correctly_triggers_zocalo_callback(
     mock_zocalo_interactor.return_value.run_start.assert_called_once()
 
 
+def test_rotation_scan_set_undulator_gap_after_xbpm_stable(
+    rotation_scan_simulated_messages,
+    test_rotation_params: RotationScan,
+):
+    msgs = assert_message_and_return_remaining(
+        rotation_scan_simulated_messages,
+        lambda msg: msg.command == "trigger" and msg.obj.name == "xbpm_feedback",
+    )
+
+    msgs = assert_message_and_return_remaining(
+        msgs, lambda msg: msg.command == "set" and msg.obj.name == "undulator"
+    )
+
+
 def test_rotation_scan_fails_with_exception_when_no_beamstop(
     sim_run_engine: RunEngineSimulator,
     fake_create_rotation_devices: RotationScanComposite,