lightning/tests/tests_pytorch/utilities/test_warnings.py

# Copyright The PyTorch Lightning 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.
"""Test that the warnings actually appear and they have the correct `stacklevel`

Needs to be run outside of `pytest` as it captures all the warnings.
"""
import os
from contextlib import redirect_stderr
from io import StringIO

from pytorch_lightning.utilities.rank_zero import _warn, rank_zero_deprecation, rank_zero_warn
from pytorch_lightning.utilities.warnings import WarningCache

standalone = os.getenv("PL_RUN_STANDALONE_TESTS", "0") == "1"
if standalone and __name__ == "__main__":

    stderr = StringIO()
    # recording
    with redirect_stderr(stderr):
        _warn("test1")
        _warn("test2", category=DeprecationWarning)

        rank_zero_warn("test3")
        rank_zero_warn("test4", category=DeprecationWarning)

        rank_zero_deprecation("test5")

        cache = WarningCache()
        cache.warn("test6")
        cache.deprecation("test7")

    output = stderr.getvalue()
    assert "test_warnings.py:31: UserWarning: test1" in output
    assert "test_warnings.py:32: DeprecationWarning: test2" in output

    assert "test_warnings.py:34: UserWarning: test3" in output
    assert "test_warnings.py:35: DeprecationWarning: test4" in output

    assert "test_warnings.py:37: LightningDeprecationWarning: test5" in output

    assert "test_warnings.py:40: UserWarning: test6" in output
    assert "test_warnings.py:41: LightningDeprecationWarning: test7" in output

    # check that logging is properly configured
    import logging

    from pytorch_lightning import _DETAIL

    root_logger = logging.getLogger()
    lightning_logger = logging.getLogger("pytorch_lightning")
    # should have a `StreamHandler`
    assert lightning_logger.hasHandlers() and len(lightning_logger.handlers) == 1
    # set our own stream for testing
    handler = lightning_logger.handlers[0]
    assert isinstance(handler, logging.StreamHandler)
    stderr = StringIO()
    # necessary with `propagate = False`
    lightning_logger.handlers[0].stream = stderr

    # necessary with `propagate = True`
    with redirect_stderr(stderr):
        # Lightning should not configure the root `logging` logger by default
        logging.info("test1")
        root_logger.info("test1")
        # but our logger instance
        lightning_logger.info("test2")
        # level is set to INFO
        lightning_logger.debug("test3")

    output = stderr.getvalue()
    assert output == "test2\n", repr(output)

    stderr = StringIO()
    lightning_logger.handlers[0].stream = stderr
    with redirect_stderr(stderr):
        # Lightning should not output DETAIL level logging by default
        lightning_logger.detail("test1")
        lightning_logger.setLevel(_DETAIL)
        lightning_logger.detail("test2")
        # logger should not output anything for DEBUG statements if set to DETAIL
        lightning_logger.debug("test3")
    output = stderr.getvalue()
    assert output == "test2\n", repr(output)