address minor review comments

tests/mocks/mock_dynamixel.py

@@ -21,10 +21,25 @@ import dynamixel_sdk as dxl
 import serial
 from mock_serial.mock_serial import MockSerial
 
-from lerobot.motors.dynamixel.dynamixel import _split_into_byte_chunks
-
 from .mock_serial_patch import WaitableStub
 
+
+def _split_into_byte_chunks(value: int, length: int) -> list[int]:
+    """Split an integer into a list of byte-sized integers (little-endian)."""
+    if length == 1:
+        data = [value]
+    elif length == 2:
+        data = [dxl.DXL_LOBYTE(value), dxl.DXL_HIBYTE(value)]
+    elif length == 4:
+        data = [
+            dxl.DXL_LOBYTE(dxl.DXL_LOWORD(value)),
+            dxl.DXL_HIBYTE(dxl.DXL_LOWORD(value)),
+            dxl.DXL_LOBYTE(dxl.DXL_HIWORD(value)),
+            dxl.DXL_HIBYTE(dxl.DXL_HIWORD(value)),
+        ]
+    return data
+
+
 # https://emanual.robotis.com/docs/en/dxl/crc/
 DXL_CRC_TABLE = [
     0x0000, 0x8005, 0x800F, 0x000A, 0x801B, 0x001E, 0x0014, 0x8011,

tests/mocks/mock_feetech.py

@@ -21,11 +21,27 @@ import scservo_sdk as scs
 import serial
 from mock_serial import MockSerial
 
-from lerobot.motors.feetech.feetech import _split_into_byte_chunks, patch_setPacketTimeout
+from lerobot.motors.feetech.feetech import patch_setPacketTimeout
 
 from .mock_serial_patch import WaitableStub
 
 
+def _split_into_byte_chunks(value: int, length: int) -> list[int]:
+    """Split an integer into a list of byte-sized integers (little-endian)."""
+    if length == 1:
+        data = [value]
+    elif length == 2:
+        data = [scs.SCS_LOBYTE(value), scs.SCS_HIBYTE(value)]
+    elif length == 4:
+        data = [
+            scs.SCS_LOBYTE(scs.SCS_LOWORD(value)),
+            scs.SCS_HIBYTE(scs.SCS_LOWORD(value)),
+            scs.SCS_LOBYTE(scs.SCS_HIWORD(value)),
+            scs.SCS_HIBYTE(scs.SCS_HIWORD(value)),
+        ]
+    return data
+
+
 class MockFeetechPacket(abc.ABC):
     @classmethod
     def build(cls, scs_id: int, params: list[int], length: int, *args, **kwargs) -> bytes: