lightning/tests/tests_pytorch/trainer/properties/test_loggers.py

# 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 pytest
from lightning.pytorch import Trainer
from lightning.pytorch.loggers import TensorBoardLogger

from tests_pytorch.loggers.test_logger import CustomLogger


def test_trainer_loggers_property():
    """Test for correct initialization of loggers in Trainer."""
    logger1 = CustomLogger()
    logger2 = CustomLogger()

    # trainer.loggers should be a copy of the input list
    trainer = Trainer(logger=[logger1, logger2])

    assert trainer.loggers == [logger1, logger2]

    # trainer.loggers should create a list of size 1
    trainer = Trainer(logger=logger1)

    assert trainer.logger == logger1
    assert trainer.loggers == [logger1]

    # trainer.loggers should be a list of size 1 holding the default logger
    trainer = Trainer(logger=True)

    assert trainer.loggers == [trainer.logger]
    assert isinstance(trainer.logger, TensorBoardLogger)


def test_trainer_loggers_setters():
    """Test the behavior of setters for trainer.logger and trainer.loggers."""
    logger1 = CustomLogger()
    logger2 = CustomLogger()

    trainer = Trainer()
    assert type(trainer.logger) is TensorBoardLogger
    assert trainer.loggers == [trainer.logger]

    # Test setters for trainer.logger
    trainer.logger = logger1
    assert trainer.logger == logger1
    assert trainer.loggers == [logger1]

    trainer.logger = None
    assert trainer.logger is None
    assert trainer.loggers == []

    # Test setters for trainer.loggers
    trainer.loggers = [logger1, logger2]
    assert trainer.loggers == [logger1, logger2]

    trainer.loggers = [logger1]
    assert trainer.loggers == [logger1]
    assert trainer.logger == logger1

    trainer.loggers = []
    assert trainer.loggers == []
    assert trainer.logger is None

    trainer.loggers = None
    assert trainer.loggers == []
    assert trainer.logger is None


@pytest.mark.parametrize(
    "logger_value",
    [
        False,
        [],
    ],
)
def test_no_logger(tmp_path, logger_value):
    """Test the cases where logger=None, logger=False, logger=[] are passed to Trainer."""
    trainer = Trainer(
        logger=logger_value,
        default_root_dir=tmp_path,
        max_steps=1,
    )
    assert trainer.logger is None
    assert trainer.loggers == []
    assert trainer.log_dir == str(tmp_path)