fix(api): don't lpd for each step in a mix (#16310)

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# Overview
If an instrument is set to have Liquid Presence Detection on and their
is a call to instrument.mix then the pipette will exit the liquid, do a
LPD and then re-enter for each cycle. This change makes it so that it
saves the state of the instrument, does LPD on the first aspirate and
then turns LPD off. Once Mix is complete then LPD is toggled back to
whatever state it was in before.
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## Risk assessment
Low: If an error somehow occurs during the mix cycle and the command is
bypassed then the instrument may be left with LPD off.
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api/src/opentrons/protocol_api/instrument_context.py

@@ -540,12 +540,12 @@ def mix(
             ),
         ):
             self.aspirate(volume, location, rate)
-            while repetitions - 1 > 0:
-                self.dispense(volume, rate=rate, **dispense_kwargs)
-                self.aspirate(volume, rate=rate)
-                repetitions -= 1
-            self.dispense(volume, rate=rate)
-
+            with AutoProbeDisable(self):
+                while repetitions - 1 > 0:
+                    self.dispense(volume, rate=rate, **dispense_kwargs)
+                    self.aspirate(volume, rate=rate)
+                    repetitions -= 1
+                self.dispense(volume, rate=rate)
         return self
 
     @requires_version(2, 0)
@@ -2192,6 +2192,22 @@ def _raise_if_configuration_not_supported_by_pipette(
             # SINGLE, QUADRANT and ALL are supported by all pipettes
 
 
+class AutoProbeDisable:
+    """Use this class to temporarily disable automatic liquid presence detection."""
+
+    def __init__(self, instrument: InstrumentContext):
+        self.instrument = instrument
+
+    def __enter__(self) -> None:
+        if self.instrument.api_version >= APIVersion(2, 21):
+            self.auto_presence = self.instrument.liquid_presence_detection
+            self.instrument.liquid_presence_detection = False
+
+    def __exit__(self, *args: Any, **kwargs: Any) -> None:
+        if self.instrument.api_version >= APIVersion(2, 21):
+            self.instrument.liquid_presence_detection = self.auto_presence
+
+
 def _raise_if_has_end_or_front_right_or_back_left(
     style: NozzleLayout,
     end: Optional[str],

api/tests/opentrons/protocol_api/test_instrument_context.py

@@ -89,6 +89,20 @@ def mock_instrument_core(decoy: Decoy) -> InstrumentCore:
     """Get a mock instrument implementation core."""
     instrument_core = decoy.mock(cls=InstrumentCore)
     decoy.when(instrument_core.get_mount()).then_return(Mount.LEFT)
+
+    # we need to add this for the mock of liquid_presence detection to actually work
+    # this replaces the mock with a a property again
+    instrument_core._liquid_presence_detection = False  # type: ignore[attr-defined]
+
+    def _setter(enable: bool) -> None:
+        instrument_core._liquid_presence_detection = enable  # type: ignore[attr-defined]
+
+    def _getter() -> bool:
+        return instrument_core._liquid_presence_detection  # type: ignore[attr-defined, no-any-return]
+
+    instrument_core.get_liquid_presence_detection = _getter  # type: ignore[method-assign]
+    instrument_core.set_liquid_presence_detection = _setter  # type: ignore[method-assign]
+
     return instrument_core
 
 
@@ -1476,3 +1490,104 @@ def test_96_tip_config_invalid(
     decoy.when(mock_instrument_core.get_nozzle_map()).then_return(nozzle_map)
     decoy.when(mock_instrument_core.get_active_channels()).then_return(96)
     assert subject._96_tip_config_valid() is True
+
+
+@pytest.mark.parametrize("api_version", [APIVersion(2, 21)])
+def test_mix_no_lpd(
+    decoy: Decoy,
+    mock_instrument_core: InstrumentCore,
+    subject: InstrumentContext,
+    mock_protocol_core: ProtocolCore,
+) -> None:
+    """It should aspirate/dispense to a well several times."""
+    mock_well = decoy.mock(cls=Well)
+
+    bottom_location = Location(point=Point(1, 2, 3), labware=mock_well)
+    input_location = Location(point=Point(2, 2, 2), labware=None)
+    last_location = Location(point=Point(9, 9, 9), labware=None)
+
+    decoy.when(mock_protocol_core.get_last_location(Mount.LEFT)).then_return(
+        last_location
+    )
+    decoy.when(
+        mock_validation.validate_location(
+            location=input_location, last_location=last_location
+        )
+    ).then_return(WellTarget(well=mock_well, location=None, in_place=False))
+    decoy.when(
+        mock_validation.validate_location(location=None, last_location=last_location)
+    ).then_return(WellTarget(well=mock_well, location=None, in_place=False))
+    decoy.when(mock_well.bottom(z=1.0)).then_return(bottom_location)
+    decoy.when(mock_instrument_core.get_aspirate_flow_rate(1.23)).then_return(5.67)
+    decoy.when(mock_instrument_core.get_dispense_flow_rate(1.23)).then_return(5.67)
+    decoy.when(mock_instrument_core.has_tip()).then_return(True)
+    decoy.when(mock_instrument_core.get_current_volume()).then_return(0.0)
+
+    subject.mix(repetitions=10, volume=10.0, location=input_location, rate=1.23)
+    decoy.verify(
+        mock_instrument_core.aspirate(),  # type: ignore[call-arg]
+        ignore_extra_args=True,
+        times=10,
+    )
+    decoy.verify(
+        mock_instrument_core.dispense(),  # type: ignore[call-arg]
+        ignore_extra_args=True,
+        times=10,
+    )
+
+    decoy.verify(
+        mock_instrument_core.liquid_probe_with_recovery(),  # type: ignore[call-arg]
+        ignore_extra_args=True,
+        times=0,
+    )
+
+
+@pytest.mark.ot3_only
+@pytest.mark.parametrize("api_version", [APIVersion(2, 21)])
+def test_mix_with_lpd(
+    decoy: Decoy,
+    mock_instrument_core: InstrumentCore,
+    subject: InstrumentContext,
+    mock_protocol_core: ProtocolCore,
+) -> None:
+    """It should aspirate/dispense to a well several times and do 1 lpd."""
+    mock_well = decoy.mock(cls=Well)
+    bottom_location = Location(point=Point(1, 2, 3), labware=mock_well)
+    input_location = Location(point=Point(2, 2, 2), labware=None)
+    last_location = Location(point=Point(9, 9, 9), labware=None)
+
+    decoy.when(mock_protocol_core.get_last_location(Mount.LEFT)).then_return(
+        last_location
+    )
+    decoy.when(
+        mock_validation.validate_location(
+            location=input_location, last_location=last_location
+        )
+    ).then_return(WellTarget(well=mock_well, location=None, in_place=False))
+    decoy.when(
+        mock_validation.validate_location(location=None, last_location=last_location)
+    ).then_return(WellTarget(well=mock_well, location=None, in_place=False))
+    decoy.when(mock_well.bottom(z=1.0)).then_return(bottom_location)
+    decoy.when(mock_instrument_core.get_aspirate_flow_rate(1.23)).then_return(5.67)
+    decoy.when(mock_instrument_core.get_dispense_flow_rate(1.23)).then_return(5.67)
+    decoy.when(mock_instrument_core.has_tip()).then_return(True)
+    decoy.when(mock_instrument_core.get_current_volume()).then_return(0.0)
+
+    subject.liquid_presence_detection = True
+    subject.mix(repetitions=10, volume=10.0, location=input_location, rate=1.23)
+    decoy.verify(
+        mock_instrument_core.aspirate(),  # type: ignore[call-arg]
+        ignore_extra_args=True,
+        times=10,
+    )
+    decoy.verify(
+        mock_instrument_core.dispense(),  # type: ignore[call-arg]
+        ignore_extra_args=True,
+        times=10,
+    )
+
+    decoy.verify(
+        mock_instrument_core.liquid_probe_with_recovery(),  # type: ignore[call-arg]
+        ignore_extra_args=True,
+        times=1,
+    )