lightning/tests/tests_fabric/utilities/test_imports.py

79 lines
2.5 KiB
Python

# Copyright The Lightning AI team.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import subprocess
import sys
from textwrap import dedent
from tests_fabric.helpers.runif import RunIf
def test_import_fabric_with_torch_dist_unavailable():
"""Test that the package can be imported regardless of whether torch.distributed is available."""
code = dedent(
"""
import torch
# pretend torch.distributed not available
for name in list(torch.distributed.__dict__.keys()):
if not name.startswith("__"):
delattr(torch.distributed, name)
torch.distributed.is_available = lambda: False
import lightning.fabric
"""
)
# run in complete isolation
assert subprocess.call([sys.executable, "-c", code]) == 0
@RunIf(deepspeed=True)
def test_import_deepspeed_lazily():
"""Test that we are importing deepspeed only when necessary."""
code = dedent(
"""
import lightning.fabric
import sys
assert 'deepspeed' not in sys.modules
from lightning.fabric.strategies import DeepSpeedStrategy
from lightning.fabric.plugins import DeepSpeedPrecision
assert 'deepspeed' not in sys.modules
import deepspeed
assert 'deepspeed' in sys.modules
"""
)
# run in complete isolation
assert subprocess.call([sys.executable, "-c", code]) == 0
@RunIf(min_python="3.9")
def test_import_lightning_multiprocessing_start_method_not_set():
"""Regression test for avoiding the lightning import to set the multiprocessing context."""
package_name = "lightning_fabric" if "lightning.fabric" == "lightning_fabric" else "lightning"
# The following would fail with "context has already been set"
code = dedent(
f"""
import sys
import multiprocessing as mp
import {package_name}
mp.set_start_method("spawn")
"""
)
# run in complete isolation
assert subprocess.call([sys.executable, "-c", code]) == 0