fix committing channel trackers on {asp,disp}96 with 1 container

Author: rickwierenga

pylabrobot/liquid_handling/liquid_handler.py

@@ -1685,16 +1685,18 @@ async def aspirate96(
     try:
       await self.backend.aspirate96(aspiration=aspiration, **backend_kwargs)
     except Exception as error:
-      for channel, container in zip(self.head96.values(), containers):
+      for channel in self.head96.values():
+        channel.get_tip().tracker.rollback()
+      for container in containers:
         if does_volume_tracking() and not container.tracker.is_disabled:
           container.tracker.rollback()
-        channel.get_tip().tracker.rollback()
-      raise error
+      raise
     else:
-      for channel, container in zip(self.head96.values(), containers):
+      for channel in self.head96.values():
+        channel.get_tip().tracker.commit()
+      for container in containers:
         if does_volume_tracking() and not container.tracker.is_disabled:
           container.tracker.commit()
-      channel.get_tip().tracker.commit()
 
   async def dispense96(
     self,
@@ -1828,16 +1830,18 @@ async def dispense96(
     try:
       await self.backend.dispense96(dispense=dispense, **backend_kwargs)
     except Exception as error:
-      for channel, container in zip(self.head96.values(), containers):
+      for channel in self.head96.values():
+        channel.get_tip().tracker.rollback()
+      for container in containers:
         if does_volume_tracking() and not container.tracker.is_disabled:
           container.tracker.rollback()
-        channel.get_tip().tracker.rollback()
-      raise error
+      raise
     else:
-      for channel, container in zip(self.head96.values(), containers):
+      for channel in self.head96.values():
+        channel.get_tip().tracker.commit()
+      for container in containers:
         if does_volume_tracking() and not container.tracker.is_disabled:
           container.tracker.commit()
-        channel.get_tip().tracker.commit()
 
   async def stamp(
     self,

pylabrobot/liquid_handling/liquid_handler_tests.py

@@ -1,7 +1,6 @@
 import itertools
 import tempfile
 import unittest
-import unittest.mock
 from typing import Any, Dict, List, Optional, Union, cast
 
 import pytest
@@ -1115,10 +1114,14 @@ async def test_96_head_volume_tracking_single_container(self):
 
     await self.lh.aspirate96(self.single_well_plate, volume=10)
     assert all(self.lh.head96[i].get_tip().tracker.get_used_volume() == 10 for i in range(96))
+    assert all(
+      self.lh.head96[i].get_tip().tracker.liquids == [(Liquid.WATER, 10)] for i in range(96)
+    )
     assert well.tracker.get_used_volume() == 0
 
     await self.lh.dispense96(self.single_well_plate, volume=10)
     assert all(self.lh.head96[i].get_tip().tracker.get_used_volume() == 0 for i in range(96))
+    assert all(self.lh.head96[i].get_tip().tracker.liquids == [] for i in range(96))
     assert well.tracker.get_used_volume() == 10 * 96
 
     await self.lh.return_tips96()