fix test imports

src/lerobot/motors/dynamixel/__init__.py

@@ -14,10 +14,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from lerobot.utils.import_utils import require_package
-
-require_package("dynamixel-sdk", extra="dynamixel", import_name="dynamixel_sdk")
-
 from .dynamixel import DriveMode, DynamixelMotorsBus, OperatingMode, TorqueMode
 from .tables import *  # noqa: F403 — hardware constant tables
 

src/lerobot/motors/dynamixel/dynamixel.py

@@ -21,6 +21,9 @@
 import logging
 from copy import deepcopy
 from enum import Enum
+from typing import TYPE_CHECKING
+
+from lerobot.utils.import_utils import is_package_available, require_package
 
 from ..encoding_utils import decode_twos_complement, encode_twos_complement
 from ..motors_bus import Motor, MotorCalibration, NameOrID, SerialMotorsBus, Value, get_address
@@ -33,6 +36,13 @@ from .tables import (
     MODEL_RESOLUTION,
 )
 
+_dynamixel_sdk_available = is_package_available("dynamixel-sdk", import_name="dynamixel_sdk")
+
+if TYPE_CHECKING or _dynamixel_sdk_available:
+    import dynamixel_sdk as dxl
+else:
+    dxl = None
+
 PROTOCOL_VERSION = 2.0
 DEFAULT_BAUDRATE = 1_000_000
 DEFAULT_TIMEOUT_MS = 1000
@@ -83,8 +93,6 @@ class TorqueMode(Enum):
 
 
 def _split_into_byte_chunks(value: int, length: int) -> list[int]:
-    import dynamixel_sdk as dxl
-
     if length == 1:
         data = [value]
     elif length == 2:
@@ -123,9 +131,8 @@ class DynamixelMotorsBus(SerialMotorsBus):
         motors: dict[str, Motor],
         calibration: dict[str, MotorCalibration] | None = None,
     ):
+        require_package("dynamixel-sdk", extra="dynamixel", import_name="dynamixel_sdk")
         super().__init__(port, motors, calibration)
-        import dynamixel_sdk as dxl
-
         self.port_handler = dxl.PortHandler(self.port)
         self.packet_handler = dxl.PacketHandler(PROTOCOL_VERSION)
         self.sync_reader = dxl.GroupSyncRead(self.port_handler, self.packet_handler, 0, 0)

src/lerobot/motors/feetech/__init__.py

@@ -14,10 +14,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from lerobot.utils.import_utils import require_package
-
-require_package("feetech-servo-sdk", extra="feetech", import_name="scservo_sdk")
-
 from .feetech import DriveMode, FeetechMotorsBus, OperatingMode, TorqueMode
 from .tables import *  # noqa: F403 — hardware constant tables
 

src/lerobot/motors/feetech/feetech.py

@@ -16,6 +16,9 @@ import logging
 from copy import deepcopy
 from enum import Enum
 from pprint import pformat
+from typing import TYPE_CHECKING
+
+from lerobot.utils.import_utils import is_package_available, require_package
 
 from ..encoding_utils import decode_sign_magnitude, encode_sign_magnitude
 from ..motors_bus import Motor, MotorCalibration, NameOrID, SerialMotorsBus, Value, get_address
@@ -32,6 +35,13 @@ from .tables import (
     SCAN_BAUDRATES,
 )
 
+_feetech_sdk_available = is_package_available("feetech-servo-sdk", import_name="scservo_sdk")
+
+if TYPE_CHECKING or _feetech_sdk_available:
+    import scservo_sdk as scs
+else:
+    scs = None
+
 DEFAULT_PROTOCOL_VERSION = 0
 DEFAULT_BAUDRATE = 1_000_000
 DEFAULT_TIMEOUT_MS = 1000
@@ -66,8 +76,6 @@ class TorqueMode(Enum):
 
 
 def _split_into_byte_chunks(value: int, length: int) -> list[int]:
-    import scservo_sdk as scs
-
     if length == 1:
         data = [value]
     elif length == 2:
@@ -119,11 +127,10 @@ class FeetechMotorsBus(SerialMotorsBus):
         calibration: dict[str, MotorCalibration] | None = None,
         protocol_version: int = DEFAULT_PROTOCOL_VERSION,
     ):
+        require_package("feetech-servo-sdk", extra="feetech", import_name="scservo_sdk")
         super().__init__(port, motors, calibration)
         self.protocol_version = protocol_version
         self._assert_same_protocol()
-        import scservo_sdk as scs
-
         self.port_handler = scs.PortHandler(self.port)
         # HACK: monkeypatch
         self.port_handler.setPacketTimeout = patch_setPacketTimeout.__get__(  # type: ignore[method-assign]
@@ -195,8 +202,6 @@ class FeetechMotorsBus(SerialMotorsBus):
         raise RuntimeError(f"Motor '{motor}' (model '{model}') was not found. Make sure it is connected.")
 
     def _find_single_motor_p1(self, motor: str, initial_baudrate: int | None = None) -> tuple[int, int]:
-        import scservo_sdk as scs
-
         model = self.motors[motor].model
         search_baudrates = (
             [initial_baudrate] if initial_baudrate is not None else self.model_baudrate_table[model]
@@ -332,8 +337,6 @@ class FeetechMotorsBus(SerialMotorsBus):
         return _split_into_byte_chunks(value, length)
 
     def _broadcast_ping(self) -> tuple[dict[int, int], int]:
-        import scservo_sdk as scs
-
         data_list: dict[int, int] = {}
 
         status_length = 6

src/lerobot/policies/groot/action_head/cross_attention_dit.py

@@ -14,26 +14,39 @@
 # limitations under the License.
 
 
+from typing import TYPE_CHECKING
+
 import torch
 import torch.nn.functional as F  # noqa: N812
+from torch import nn
 
-from lerobot.utils.import_utils import require_package
+from lerobot.utils.import_utils import is_package_available, require_package
 
-require_package("diffusers", extra="groot")
+_diffusers_available = is_package_available("diffusers")
 
-from diffusers import ConfigMixin, ModelMixin  # noqa: E402
-from diffusers.configuration_utils import register_to_config  # noqa: E402
-from diffusers.models.attention import Attention, FeedForward  # noqa: E402
-from diffusers.models.embeddings import (  # noqa: E402
-    SinusoidalPositionalEmbedding,
-    TimestepEmbedding,
-    Timesteps,
-)
-from torch import nn  # noqa: E402
+if TYPE_CHECKING or _diffusers_available:
+    from diffusers import ConfigMixin, ModelMixin
+    from diffusers.configuration_utils import register_to_config
+    from diffusers.models.attention import Attention, FeedForward
+    from diffusers.models.embeddings import (
+        SinusoidalPositionalEmbedding,
+        TimestepEmbedding,
+        Timesteps,
+    )
+else:
+    ConfigMixin = object
+    ModelMixin = nn.Module
+    register_to_config = lambda fn: fn  # noqa: E731
+    Attention = None
+    FeedForward = None
+    SinusoidalPositionalEmbedding = None
+    TimestepEmbedding = None
+    Timesteps = None
 
 
 class TimestepEncoder(nn.Module):
     def __init__(self, embedding_dim, compute_dtype=torch.float32):
+        require_package("diffusers", extra="groot")
         super().__init__()
         self.time_proj = Timesteps(num_channels=256, flip_sin_to_cos=True, downscale_freq_shift=1)
         self.timestep_embedder = TimestepEmbedding(in_channels=256, time_embed_dim=embedding_dim)
@@ -93,6 +106,7 @@ class BasicTransformerBlock(nn.Module):
         ff_bias: bool = True,
         attention_out_bias: bool = True,
     ):
+        require_package("diffusers", extra="groot")
         super().__init__()
         self.dim = dim
         self.num_attention_heads = num_attention_heads

tests/async_inference/test_helpers.py

@@ -16,10 +16,14 @@ import math
 import pickle
 import time
 
-import numpy as np
-import torch
+import pytest
 
-from lerobot.async_inference.helpers import (
+pytest.importorskip("grpc")
+
+import numpy as np  # noqa: E402
+import torch  # noqa: E402
+
+from lerobot.async_inference.helpers import (  # noqa: E402
     FPSTracker,
     TimedAction,
     TimedObservation,

tests/rl/test_queue.py

@@ -18,9 +18,13 @@ import threading
 import time
 from queue import Queue
 
-from torch.multiprocessing import Queue as TorchMPQueue
+import pytest
 
-from lerobot.rl.queue import get_last_item_from_queue
+pytest.importorskip("grpc")
+
+from torch.multiprocessing import Queue as TorchMPQueue  # noqa: E402
+
+from lerobot.rl.queue import get_last_item_from_queue  # noqa: E402
 
 
 def test_get_last_item_single_item():

tests/utils/test_process.py

@@ -22,7 +22,9 @@ from unittest.mock import patch
 
 import pytest
 
-from lerobot.rl.process import ProcessSignalHandler
+pytest.importorskip("grpc")
+
+from lerobot.rl.process import ProcessSignalHandler  # noqa: E402
 
 
 # Fixture to reset shutdown_event_counter and original signal handlers before and after each test

tests/utils/test_replay_buffer.py

@@ -18,12 +18,15 @@ import sys
 from collections.abc import Callable
 
 import pytest
-import torch
 
-from lerobot.datasets.lerobot_dataset import LeRobotDataset
-from lerobot.rl.buffer import BatchTransition, ReplayBuffer, random_crop_vectorized
-from lerobot.utils.constants import ACTION, DONE, OBS_IMAGE, OBS_STATE, OBS_STR, REWARD
-from tests.fixtures.constants import DUMMY_REPO_ID
+pytest.importorskip("grpc")
+
+import torch  # noqa: E402
+
+from lerobot.datasets.lerobot_dataset import LeRobotDataset  # noqa: E402
+from lerobot.rl.buffer import BatchTransition, ReplayBuffer, random_crop_vectorized  # noqa: E402
+from lerobot.utils.constants import ACTION, DONE, OBS_IMAGE, OBS_STATE, OBS_STR, REWARD  # noqa: E402
+from tests.fixtures.constants import DUMMY_REPO_ID  # noqa: E402
 
 
 def state_dims() -> list[str]: