add version gate to preserve 2.16 and 2.17 alternating tip drop behavior

api/src/opentrons/protocol_api/instrument_context.py

@@ -60,6 +60,8 @@
 """The version after which a partial nozzle configuration became available for the 96 Channel Pipette."""
 _PARTIAL_NOZZLE_CONFIGURATION_AUTOMATIC_TIP_TRACKING_IN = APIVersion(2, 18)
 """The version after which automatic tip tracking supported partially configured nozzle layouts."""
+_DISPOSAL_LOCATION_OFFSET_ADDED_IN = APIVersion(2, 18)
+"""The version after which offsets for deck configured trash containers and changes to alternating tip drop behavior were introduced."""
 
 
 class InstrumentContext(publisher.CommandPublisher):
@@ -1086,16 +1088,22 @@ def drop_tip(
             well = maybe_well
 
         elif isinstance(location, (TrashBin, WasteChute)):
+            # In 2.16 and 2.17, we would always automatically use automatic alternate tip drop locations regardless
+            # of whether you explicitly passed the disposal location as a location or if none was provided. Now, in
+            # 2.18 and moving forward, passing it in will bypass the automatic behavior and instead go to the set
+            # offset or the XY center if none is provided.
+            if self.api_version < _DISPOSAL_LOCATION_OFFSET_ADDED_IN:
+                alternate_drop_location = True
             with publisher.publish_context(
                 broker=self.broker,
                 command=cmds.drop_tip_in_disposal_location(
                     instrument=self, location=location
                 ),
             ):
-                # TODO(jbl 2024-02-28) when adding 2.18 api version checks, set alternate_tip_drop
-                #   if below that version for compatability
                 self._core.drop_tip_in_disposal_location(
-                    location, home_after=home_after
+                    location,
+                    home_after=home_after,
+                    alternate_tip_drop=alternate_drop_location,
                 )
             self._last_tip_picked_up_from = None
             return self

api/tests/opentrons/protocol_api/test_instrument_context.py

@@ -753,9 +753,14 @@ def test_drop_tip_to_randomized_trash_location(
     )
 
 
+@pytest.mark.parametrize(
+    ["api_version", "alternate_drop"],
+    [(APIVersion(2, 17), True), (APIVersion(2, 18), False)],
+)
 def test_drop_tip_in_trash_bin(
     decoy: Decoy,
     mock_instrument_core: InstrumentCore,
+    alternate_drop: bool,
     subject: InstrumentContext,
 ) -> None:
     """It should drop a tip in a deck configured trash bin."""
@@ -767,14 +772,20 @@ def test_drop_tip_in_trash_bin(
         mock_instrument_core.drop_tip_in_disposal_location(
             trash_bin,
             home_after=None,
+            alternate_tip_drop=alternate_drop,
         ),
         times=1,
     )
 
 
+@pytest.mark.parametrize(
+    ["api_version", "alternate_drop"],
+    [(APIVersion(2, 17), True), (APIVersion(2, 18), False)],
+)
 def test_drop_tip_in_waste_chute(
     decoy: Decoy,
     mock_instrument_core: InstrumentCore,
+    alternate_drop: bool,
     subject: InstrumentContext,
 ) -> None:
     """It should drop a tip in a deck configured trash bin or waste chute."""
@@ -786,6 +797,7 @@ def test_drop_tip_in_waste_chute(
         mock_instrument_core.drop_tip_in_disposal_location(
             waste_chute,
             home_after=None,
+            alternate_tip_drop=alternate_drop,
         ),
         times=1,
     )