Add WatchableAsyncStatus support to the xbpm_feedback status (#1928)

* Add WatchableAsyncStatus support to the xbpm_feedback status

Author: rtuck99

src/dodal/devices/xbpm_feedback.py

@@ -1,5 +1,12 @@
 from bluesky.protocols import Triggerable
-from ophyd_async.core import AsyncStatus, Device, Reference, StrictEnum, observe_value
+from ophyd_async.core import (
+    Device,
+    Reference,
+    StrictEnum,
+    WatchableAsyncStatus,
+    WatcherUpdate,
+    observe_value,
+)
 from ophyd_async.epics.core import epics_signal_r, epics_signal_rw
 
 from dodal.common.device_utils import periodic_reminder
@@ -24,12 +31,21 @@ def __init__(self, prefix: str, name: str = "", baton: Baton | None = None) -> N
         self.baton_ref = Reference(baton) if baton else None
         super().__init__(name=name)
 
-    @AsyncStatus.wrap
+    @WatchableAsyncStatus.wrap
     async def trigger(self):
         if self.baton_ref and await self.baton_ref().commissioning.get_value():
             LOGGER.warning("Commissioning mode enabled, ignoring feedback")
         else:
             async with periodic_reminder("Waiting for XBPM"):
+                initial = None
                 async for value in observe_value(self.pos_stable):
+                    if initial is None:
+                        initial = value
+                    yield WatcherUpdate(
+                        current=value,
+                        initial=initial,
+                        target=1,
+                        name=self.pos_stable.name,
+                    )
                     if value:
                         return

tests/devices/test_xbpm_feedback.py

@@ -5,7 +5,7 @@
 import pytest
 from bluesky import plan_stubs as bps
 from bluesky.run_engine import RunEngine
-from ophyd_async.core import init_devices, set_mock_value
+from ophyd_async.core import WatchableAsyncStatus, init_devices, set_mock_value
 
 from dodal.devices.baton import Baton
 from dodal.devices.xbpm_feedback import XBPMFeedback
@@ -15,7 +15,7 @@
 async def fake_xbpm_feedback() -> XBPMFeedback:
     async with init_devices(mock=True):
         baton = Baton("BATON-01:")
-        xbpm_feedback = XBPMFeedback("", baton=baton)
+        xbpm_feedback = XBPMFeedback("", baton=baton, name="xbpm_feedback")
     return xbpm_feedback
 
 
@@ -108,3 +108,33 @@ def test_xbpm_feedback_does_not_wait_if_commissioning_mode_enabled(
     run_engine(bps.trigger(xbpm_feedback_in_commissioning_mode, wait=True))
     mock_periodic_reminder.assert_not_called()
     mock_observe_value.assert_not_called()
+
+
+async def test_xbpm_feedback_trigger_is_watchable(
+    fake_xbpm_feedback: XBPMFeedback,
+    run_engine: RunEngine,
+):
+    set_mock_value(fake_xbpm_feedback.pos_stable, False)
+    received_events = []
+
+    def on_event(**kwargs):
+        received_events.append(kwargs)
+        if kwargs.get("current") == 0:
+            set_mock_value(fake_xbpm_feedback.pos_stable, True)
+
+    def wait_for_feedback():
+        status = yield from bps.trigger(fake_xbpm_feedback, wait=False)
+        assert isinstance(status, WatchableAsyncStatus)
+        status.watch(on_event)  # type: ignore
+        yield from bps.wait(timeout=1)
+
+    run_engine(wait_for_feedback())
+
+    assert received_events[0]["name"] == "xbpm_feedback-pos_stable"
+    assert received_events[0]["current"] == 0
+    assert received_events[0]["initial"] == 0
+    assert received_events[0]["target"] == 1
+    assert received_events[1]["name"] == "xbpm_feedback-pos_stable"
+    assert received_events[1]["current"] == 1
+    assert received_events[1]["initial"] == 0
+    assert received_events[1]["target"] == 1