Improve wandb tests

[ghost]

The tests of the wandb-logger are not as comprehensive as for the rest of the loggers. Currently, they just test if constructing a logger works.

Testing wandb in the same way as the other loggers works:

def test_wandb_logger(tmpdir):
    """Verify that basic functionality of wandb logger works."""
    tutils.reset_seed()

    wandb_dir = os.path.join(tmpdir, "wandb")
    logger = WandbLogger(save_dir=wandb_dir, anonymous=True, offline=True)

    hparams = tutils.get_hparams()
    model = LightningTestModel(hparams)

    trainer_options = dict(
        default_save_path=tmpdir,
        max_epochs=1,
        train_percent_check=0.05,
        logger=logger
    )

    trainer = Trainer(**trainer_options)
    result = trainer.fit(model)

    print('result finished')
    assert result == 1, "Training failed"


def test_wandb_pickle(tmpdir):
    """Verify that pickling trainer with wandb logger works."""
    tutils.reset_seed()

    wandb_dir = str(tmpdir)
    logger = WandbLogger(save_dir=wandb_dir, anonymous=True)
    trainer_options = dict(
        default_save_path=tmpdir,
        max_epochs=1,
        logger=logger
    )

    trainer = Trainer(**trainer_options)
    pkl_bytes = pickle.dumps(trainer)
    trainer2 = pickle.loads(pkl_bytes)
    trainer2.logger.log_metrics({"acc": 1.0})

But the CI tests on github for windows fail. The tests for Ubuntu and Mac work. Seems to be some problem related to file-access that I cannot recreate locally

[Borda]

@borisdayma mind send a PR? 🦝

[borisdayma]

I think you guys fixed it here: f862d9f

[edenlightning]

@Borda can we close this?

[Borda]

can we close this?

not yeat as wandb is not included in the stand test suite
https://github.com/PyTorchLightning/pytorch-lightning/blob/9e8716afe8bd535ecb468027a8a4c919a3ae16d1/tests/loggers/test_all.py#L29
https://github.com/PyTorchLightning/pytorch-lightning/blob/9e8716afe8bd535ecb468027a8a4c919a3ae16d1/tests/loggers/test_all.py#L76

[awaelchli]

The wandb logger is now included in the other tests as well and the todos that @Borda pointed out are gone.
It is tested also for pickling and folder structure / paths for logged files.
I would argue it is now at the similar level as other loggers. Shall we close?