fix(api): prevent moving a labware onto itself

[jbleon95]

Overview

Fixes PLAT-572.

This PR fixes a bug found where you were able to move a labware that could be stacked upon the same labware type (for example, the thermocycler lid) onto the same instance of the labware, ie.e stacking it on itself. Not only does this make no logical or physical sense, it would cause a RecursionError the next time any gantry movement happened, since during the course of finding the highest Z we would recursively find the height of any stacked labware. If a labware's parent happens to be itself (which should never happen), it will keep recursively trying to find a deck slot or module until the max recursion error occurs.

Now, when moving to an OnLabwareLocation, we check to make sure that the labware ID of the labware being moved does not match the labware ID of the new location. If it does, we will raise an error informing that the labware is trying to be moved on itself.

For more information on this recursive error, see PR #16600.

Test Plan and Hands on Testing

The following protocol now fails with a LabwareMovementNotAllowedError on the move_labware line, not with a RecursionError on the pick_up_tip line.

metadata = {
    'protocolName': 'Impossible Geometry Stacking Test',
}

requirements = {
    "robotType": "Flex",
    "apiLevel": "2.20"
}


def run(context):
    trash_bin = context.load_trash_bin('A3')
    tip_rack = context.load_labware('opentrons_flex_96_tiprack_50ul', 'D2')
    pipette = context.load_instrument('flex_1channel_50', mount="left", tip_racks=[tip_rack])

    lid1 = context.load_labware("opentrons_tough_pcr_auto_sealing_lid", "C3")
    lid2 = lid1.load_labware("opentrons_tough_pcr_auto_sealing_lid")

    context.move_labware(lid2, lid2, use_gripper=True)

    pipette.pick_up_tip()

Changelog

• Prevent moving a labware onto the same instance of labware

Risk assessment

Low.

[vegano1]

This is perfect, thank you.

However, what about this case?

[ecormany]

Yep, that's the error!