Ejemplo n.º 1
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def test_testtube_pickle():
    """
    Verify that pickling a trainer containing a test tube logger works
    """
    tutils.reset_seed()

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

    save_dir = tutils.init_save_dir()

    logger = tutils.get_test_tube_logger(False)
    logger.log_hyperparams(hparams)
    logger.save()

    trainer_options = dict(max_nb_epochs=1,
                           train_percent_check=0.01,
                           logger=logger)

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

    tutils.clear_save_dir()
Ejemplo n.º 2
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def test_simple_cpu():
    """
    Verify continue training session on CPU
    :return:
    """
    tutils.reset_seed()

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

    save_dir = tutils.init_save_dir()

    # logger file to get meta
    trainer_options = dict(
        max_nb_epochs=1,
        val_percent_check=0.1,
        train_percent_check=0.1,
    )

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

    # traning complete
    assert result == 1, 'amp + ddp model failed to complete'

    tutils.clear_save_dir()
Ejemplo n.º 3
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def test_running_test_after_fitting():
    """Verify test() on fitted model"""
    tutils.reset_seed()

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

    save_dir = tutils.init_save_dir()

    # logger file to get meta
    logger = tutils.get_test_tube_logger(False)

    # logger file to get weights
    checkpoint = tutils.init_checkpoint_callback(logger)

    trainer_options = dict(show_progress_bar=False,
                           max_nb_epochs=1,
                           train_percent_check=0.4,
                           val_percent_check=0.2,
                           test_percent_check=0.2,
                           checkpoint_callback=checkpoint,
                           logger=logger)

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

    assert result == 1, 'training failed to complete'

    trainer.test()

    # test we have good test accuracy
    tutils.assert_ok_test_acc(trainer)

    tutils.clear_save_dir()
Ejemplo n.º 4
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def test_model_saving_loading():
    """
    Tests use case where trainer saves the model, and user loads it from tags independently
    :return:
    """
    tutils.reset_seed()

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

    save_dir = tutils.init_save_dir()

    # logger file to get meta
    logger = tutils.get_test_tube_logger(False)

    trainer_options = dict(
        max_nb_epochs=1,
        logger=logger,
        checkpoint_callback=ModelCheckpoint(save_dir)
    )

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

    # traning complete
    assert result == 1, 'amp + ddp model failed to complete'

    # make a prediction
    for dataloader in model.test_dataloader():
        for batch in dataloader:
            break

    x, y = batch
    x = x.view(x.size(0), -1)

    # generate preds before saving model
    model.eval()
    pred_before_saving = model(x)

    # save model
    new_weights_path = os.path.join(save_dir, 'save_test.ckpt')
    trainer.save_checkpoint(new_weights_path)

    # load new model
    tags_path = logger.experiment.get_data_path(logger.experiment.name, logger.experiment.version)
    tags_path = os.path.join(tags_path, 'meta_tags.csv')
    model_2 = LightningTestModel.load_from_metrics(weights_path=new_weights_path,
                                                   tags_csv=tags_path)
    model_2.eval()

    # make prediction
    # assert that both predictions are the same
    new_pred = model_2(x)
    assert torch.all(torch.eq(pred_before_saving, new_pred)).item() == 1

    tutils.clear_save_dir()
Ejemplo n.º 5
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def test_running_test_pretrained_model_ddp():
    """Verify test() on pretrained model"""
    if not tutils.can_run_gpu_test():
        return

    tutils.reset_seed()
    tutils.set_random_master_port()

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

    save_dir = tutils.init_save_dir()

    # exp file to get meta
    logger = tutils.get_test_tube_logger(False)

    # exp file to get weights
    checkpoint = tutils.init_checkpoint_callback(logger)

    trainer_options = dict(
        show_progress_bar=False,
        max_nb_epochs=1,
        train_percent_check=0.4,
        val_percent_check=0.2,
        checkpoint_callback=checkpoint,
        logger=logger,
        gpus=[0, 1],
        distributed_backend='ddp'
    )

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

    exp = logger.experiment
    logging.info(os.listdir(exp.get_data_path(exp.name, exp.version)))

    # correct result and ok accuracy
    assert result == 1, 'training failed to complete'
    pretrained_model = tutils.load_model(logger.experiment,
                                         trainer.checkpoint_callback.filepath,
                                         module_class=LightningTestModel)

    # run test set
    new_trainer = Trainer(**trainer_options)
    new_trainer.test(pretrained_model)

    for dataloader in model.test_dataloader():
        tutils.run_prediction(dataloader, pretrained_model)

    tutils.clear_save_dir()
Ejemplo n.º 6
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def test_running_test_pretrained_model_dp():
    tutils.reset_seed()

    """Verify test() on pretrained model"""
    if not tutils.can_run_gpu_test():
        return

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

    save_dir = tutils.init_save_dir()

    # logger file to get meta
    logger = tutils.get_test_tube_logger(False)

    # logger file to get weights
    checkpoint = tutils.init_checkpoint_callback(logger)

    trainer_options = dict(
        show_progress_bar=True,
        max_nb_epochs=1,
        train_percent_check=0.4,
        val_percent_check=0.2,
        checkpoint_callback=checkpoint,
        logger=logger,
        gpus=[0, 1],
        distributed_backend='dp'
    )

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

    # correct result and ok accuracy
    assert result == 1, 'training failed to complete'
    pretrained_model = tutils.load_model(logger.experiment,
                                         trainer.checkpoint_callback.filepath,
                                         module_class=LightningTestModel)

    new_trainer = Trainer(**trainer_options)
    new_trainer.test(pretrained_model)

    # test we have good test accuracy
    tutils.assert_ok_test_acc(new_trainer)
    tutils.clear_save_dir()
Ejemplo n.º 7
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def test_no_val_end_module():
    """
    Tests use case where trainer saves the model, and user loads it from tags independently
    :return:
    """
    tutils.reset_seed()

    class CurrentTestModel(LightningValidationStepMixin,
                           LightningTestModelBase):
        pass

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

    save_dir = tutils.init_save_dir()

    # logger file to get meta
    logger = tutils.get_test_tube_logger(False)

    trainer_options = dict(max_nb_epochs=1,
                           logger=logger,
                           checkpoint_callback=ModelCheckpoint(save_dir))

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

    # traning complete
    assert result == 1, 'amp + ddp model failed to complete'

    # save model
    new_weights_path = os.path.join(save_dir, 'save_test.ckpt')
    trainer.save_checkpoint(new_weights_path)

    # load new model
    tags_path = logger.experiment.get_data_path(logger.experiment.name,
                                                logger.experiment.version)
    tags_path = os.path.join(tags_path, 'meta_tags.csv')
    model_2 = LightningTestModel.load_from_metrics(
        weights_path=new_weights_path, tags_csv=tags_path)
    model_2.eval()

    # make prediction
    tutils.clear_save_dir()
Ejemplo n.º 8
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def test_load_model_from_checkpoint():
    tutils.reset_seed()

    """Verify test() on pretrained model"""
    hparams = tutils.get_hparams()
    model = LightningTestModel(hparams)

    save_dir = tutils.init_save_dir()

    trainer_options = dict(
        show_progress_bar=False,
        max_nb_epochs=1,
        train_percent_check=0.4,
        val_percent_check=0.2,
        checkpoint_callback=True,
        logger=False,
        default_save_path=save_dir
    )

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

    # correct result and ok accuracy
    assert result == 1, 'training failed to complete'
    pretrained_model = LightningTestModel.load_from_checkpoint(
        os.path.join(trainer.checkpoint_callback.filepath, "_ckpt_epoch_0.ckpt")
    )

    # test that hparams loaded correctly
    for k, v in vars(hparams).items():
        assert getattr(pretrained_model.hparams, k) == v

    new_trainer = Trainer(**trainer_options)
    new_trainer.test(pretrained_model)

    # test we have good test accuracy
    tutils.assert_ok_test_acc(new_trainer)
    tutils.clear_save_dir()
Ejemplo n.º 9
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def test_testtube_logger():
    """
    verify that basic functionality of test tube logger works
    """
    tutils.reset_seed()
    hparams = tutils.get_hparams()
    model = LightningTestModel(hparams)

    save_dir = tutils.init_save_dir()

    logger = tutils.get_test_tube_logger(False)

    trainer_options = dict(max_nb_epochs=1,
                           train_percent_check=0.01,
                           logger=logger)

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

    assert result == 1, "Training failed"

    tutils.clear_save_dir()
Ejemplo n.º 10
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def test_running_test_without_val():
    tutils.reset_seed()
    """Verify test() works on a model with no val_loader"""
    class CurrentTestModel(LightningTestMixin, LightningTestModelBase):
        pass

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

    save_dir = tutils.init_save_dir()

    # logger file to get meta
    logger = tutils.get_test_tube_logger(False)

    # logger file to get weights
    checkpoint = tutils.init_checkpoint_callback(logger)

    trainer_options = dict(show_progress_bar=False,
                           max_nb_epochs=1,
                           train_percent_check=0.4,
                           val_percent_check=0.2,
                           test_percent_check=0.2,
                           checkpoint_callback=checkpoint,
                           logger=logger)

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

    assert result == 1, 'training failed to complete'

    trainer.test()

    # test we have good test accuracy
    tutils.assert_ok_test_acc(trainer)

    tutils.clear_save_dir()
Ejemplo n.º 11
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def test_cpu_restore_training():
    """
    Verify continue training session on CPU
    :return:
    """
    tutils.reset_seed()

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

    save_dir = tutils.init_save_dir()

    # logger file to get meta
    test_logger_version = 10
    logger = tutils.get_test_tube_logger(False, version=test_logger_version)

    trainer_options = dict(
        max_nb_epochs=2,
        val_check_interval=0.50,
        val_percent_check=0.2,
        train_percent_check=0.2,
        logger=logger,
        checkpoint_callback=ModelCheckpoint(save_dir)
    )

    # fit model
    trainer = Trainer(**trainer_options)
    result = trainer.fit(model)
    real_global_epoch = trainer.current_epoch

    # traning complete
    assert result == 1, 'amp + ddp model failed to complete'

    # wipe-out trainer and model
    # retrain with not much data... this simulates picking training back up after slurm
    # we want to see if the weights come back correctly
    new_logger = tutils.get_test_tube_logger(False, version=test_logger_version)
    trainer_options = dict(
        max_nb_epochs=2,
        val_check_interval=0.50,
        val_percent_check=0.2,
        train_percent_check=0.2,
        logger=new_logger,
        checkpoint_callback=ModelCheckpoint(save_dir),
    )
    trainer = Trainer(**trainer_options)
    model = LightningTestModel(hparams)

    # set the epoch start hook so we can predict before the model does the full training
    def assert_good_acc():
        assert trainer.current_epoch == real_global_epoch
        assert trainer.current_epoch >= 0

        # if model and state loaded correctly, predictions will be good even though we
        # haven't trained with the new loaded model
        trainer.model.eval()
        for dataloader in trainer.get_val_dataloaders():
            tutils.run_prediction(dataloader, trainer.model)

    model.on_sanity_check_start = assert_good_acc

    # by calling fit again, we trigger training, loading weights from the cluster
    # and our hook to predict using current model before any more weight updates
    trainer.fit(model)

    tutils.clear_save_dir()
Ejemplo n.º 12
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def test_dp_resume():
    """
    Make sure DP continues training correctly
    :return:
    """
    if not tutils.can_run_gpu_test():
        return

    tutils.reset_seed()

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

    trainer_options = dict(
        show_progress_bar=True,
        max_nb_epochs=2,
        gpus=2,
        distributed_backend='dp',
    )

    save_dir = tutils.init_save_dir()

    # get logger
    logger = tutils.get_test_tube_logger(debug=False)

    # exp file to get weights
    # logger file to get weights
    checkpoint = tutils.init_checkpoint_callback(logger)

    # add these to the trainer options
    trainer_options['logger'] = logger
    trainer_options['checkpoint_callback'] = checkpoint

    # fit model
    trainer = Trainer(**trainer_options)
    trainer.is_slurm_managing_tasks = True
    result = trainer.fit(model)

    # track epoch before saving
    real_global_epoch = trainer.current_epoch

    # correct result and ok accuracy
    assert result == 1, 'amp + dp model failed to complete'

    # ---------------------------
    # HPC LOAD/SAVE
    # ---------------------------
    # save
    trainer.hpc_save(save_dir, logger)

    # init new trainer
    new_logger = tutils.get_test_tube_logger(version=logger.version)
    trainer_options['logger'] = new_logger
    trainer_options['checkpoint_callback'] = ModelCheckpoint(save_dir)
    trainer_options['train_percent_check'] = 0.2
    trainer_options['val_percent_check'] = 0.2
    trainer_options['max_nb_epochs'] = 1
    new_trainer = Trainer(**trainer_options)

    # set the epoch start hook so we can predict before the model does the full training
    def assert_good_acc():
        assert new_trainer.current_epoch == real_global_epoch and new_trainer.current_epoch > 0

        # if model and state loaded correctly, predictions will be good even though we
        # haven't trained with the new loaded model
        dp_model = new_trainer.model
        dp_model.eval()

        dataloader = trainer.get_train_dataloader()
        tutils.run_prediction(dataloader, dp_model, dp=True)

    # new model
    model = LightningTestModel(hparams)
    model.on_sanity_check_start = assert_good_acc

    # fit new model which should load hpc weights
    new_trainer.fit(model)

    # test freeze on gpu
    model.freeze()
    model.unfreeze()

    tutils.clear_save_dir()
Ejemplo n.º 13
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def test_amp_gpu_ddp_slurm_managed():
    """
    Make sure DDP + AMP work
    :return:
    """
    if not tutils.can_run_gpu_test():
        return

    tutils.reset_seed()

    # simulate setting slurm flags
    tutils.set_random_master_port()
    os.environ['SLURM_LOCALID'] = str(0)

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

    trainer_options = dict(show_progress_bar=True,
                           max_nb_epochs=1,
                           gpus=[0],
                           distributed_backend='ddp',
                           use_amp=True)

    save_dir = tutils.init_save_dir()

    # exp file to get meta
    logger = tutils.get_test_tube_logger(False)

    # exp file to get weights
    checkpoint = tutils.init_checkpoint_callback(logger)

    # add these to the trainer options
    trainer_options['checkpoint_callback'] = checkpoint
    trainer_options['logger'] = logger

    # fit model
    trainer = Trainer(**trainer_options)
    trainer.is_slurm_managing_tasks = True
    result = trainer.fit(model)

    # correct result and ok accuracy
    assert result == 1, 'amp + ddp model failed to complete'

    # test root model address
    assert trainer.resolve_root_node_address('abc') == 'abc'
    assert trainer.resolve_root_node_address('abc[23]') == 'abc23'
    assert trainer.resolve_root_node_address('abc[23-24]') == 'abc23'
    assert trainer.resolve_root_node_address(
        'abc[23-24, 45-40, 40]') == 'abc23'

    # test model loading with a map_location
    pretrained_model = tutils.load_model(logger.experiment,
                                         trainer.checkpoint_callback.filepath)

    # test model preds
    for dataloader in trainer.get_test_dataloaders():
        tutils.run_prediction(dataloader, pretrained_model)

    if trainer.use_ddp:
        # on hpc this would work fine... but need to hack it for the purpose of the test
        trainer.model = pretrained_model
        trainer.optimizers, trainer.lr_schedulers = pretrained_model.configure_optimizers(
        )

    # test HPC loading / saving
    trainer.hpc_save(save_dir, logger)
    trainer.hpc_load(save_dir, on_gpu=True)

    # test freeze on gpu
    model.freeze()
    model.unfreeze()

    tutils.clear_save_dir()
Ejemplo n.º 14
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def test_tbptt_cpu_model():
    """
    Test truncated back propagation through time works.
    :return:
    """
    tutils.reset_seed()

    save_dir = tutils.init_save_dir()

    truncated_bptt_steps = 2
    sequence_size = 30
    batch_size = 30

    x_seq = torch.rand(batch_size, sequence_size, 1)
    y_seq_list = torch.rand(batch_size, sequence_size, 1).tolist()

    class MockSeq2SeqDataset(torch.utils.data.Dataset):
        def __getitem__(self, i):
            return x_seq, y_seq_list

        def __len__(self):
            return 1

    class BpttTestModel(LightningTestModelBase):
        def __init__(self, hparams):
            super().__init__(hparams)
            self.test_hidden = None

        def training_step(self, batch, batch_idx, hiddens):
            assert hiddens == self.test_hidden, "Hidden state not persistent between tbptt steps"
            self.test_hidden = torch.rand(1)

            x_tensor, y_list = batch
            assert x_tensor.shape[
                1] == truncated_bptt_steps, "tbptt split Tensor failed"

            y_tensor = torch.tensor(y_list, dtype=x_tensor.dtype)
            assert y_tensor.shape[
                1] == truncated_bptt_steps, "tbptt split list failed"

            pred = self.forward(x_tensor.view(batch_size,
                                              truncated_bptt_steps))
            loss_val = torch.nn.functional.mse_loss(
                pred, y_tensor.view(batch_size, truncated_bptt_steps))
            return {
                'loss': loss_val,
                'hiddens': self.test_hidden,
            }

        @data_loader
        def train_dataloader(self):
            return torch.utils.data.DataLoader(
                dataset=MockSeq2SeqDataset(),
                batch_size=batch_size,
                shuffle=False,
                sampler=None,
            )

    trainer_options = dict(
        max_nb_epochs=1,
        truncated_bptt_steps=truncated_bptt_steps,
        val_percent_check=0,
        weights_summary=None,
    )

    hparams = tutils.get_hparams()
    hparams.batch_size = batch_size
    hparams.in_features = truncated_bptt_steps
    hparams.hidden_dim = truncated_bptt_steps
    hparams.out_features = truncated_bptt_steps

    model = BpttTestModel(hparams)

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

    assert result == 1, 'training failed to complete'

    tutils.clear_save_dir()
Ejemplo n.º 15
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def test_cpu_slurm_save_load():
    """
    Verify model save/load/checkpoint on CPU
    :return:
    """
    tutils.reset_seed()

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

    save_dir = tutils.init_save_dir()

    # logger file to get meta
    logger = tutils.get_test_tube_logger(False)

    version = logger.version

    trainer_options = dict(max_nb_epochs=1,
                           logger=logger,
                           checkpoint_callback=ModelCheckpoint(save_dir))

    # fit model
    trainer = Trainer(**trainer_options)
    result = trainer.fit(model)
    real_global_step = trainer.global_step

    # traning complete
    assert result == 1, 'amp + ddp model failed to complete'

    # predict with trained model before saving
    # make a prediction
    for dataloader in model.test_dataloader():
        for batch in dataloader:
            break

    x, y = batch
    x = x.view(x.size(0), -1)

    model.eval()
    pred_before_saving = model(x)

    # test HPC saving
    # simulate snapshot on slurm
    saved_filepath = trainer.hpc_save(save_dir, logger)
    assert os.path.exists(saved_filepath)

    # new logger file to get meta
    logger = tutils.get_test_tube_logger(False, version=version)

    trainer_options = dict(
        max_nb_epochs=1,
        logger=logger,
        checkpoint_callback=ModelCheckpoint(save_dir),
    )
    trainer = Trainer(**trainer_options)
    model = LightningTestModel(hparams)

    # set the epoch start hook so we can predict before the model does the full training
    def assert_pred_same():
        assert trainer.global_step == real_global_step and trainer.global_step > 0

        # predict with loaded model to make sure answers are the same
        trainer.model.eval()
        new_pred = trainer.model(x)
        assert torch.all(torch.eq(pred_before_saving, new_pred)).item() == 1

    model.on_epoch_start = assert_pred_same

    # by calling fit again, we trigger training, loading weights from the cluster
    # and our hook to predict using current model before any more weight updates
    trainer.fit(model)

    tutils.clear_save_dir()
Ejemplo n.º 16
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def test_model_checkpoint_options():
    """
    Test ModelCheckpoint options
    :return:
    """
    def mock_save_function(filepath):
        open(filepath, 'a').close()

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

    # simulated losses
    save_dir = tutils.init_save_dir()
    losses = [10, 9, 2.8, 5, 2.5]

    # -----------------
    # CASE K=-1  (all)
    w = ModelCheckpoint(save_dir, save_top_k=-1, verbose=1)
    w.save_function = mock_save_function
    for i, loss in enumerate(losses):
        w.on_epoch_end(i, logs={'val_loss': loss})

    file_lists = set(os.listdir(save_dir))

    assert len(file_lists) == len(
        losses), "Should save all models when save_top_k=-1"

    # verify correct naming
    for i in range(0, len(losses)):
        assert f'_ckpt_epoch_{i}.ckpt' in file_lists

    tutils.clear_save_dir()

    # -----------------
    # CASE K=0 (none)
    w = ModelCheckpoint(save_dir, save_top_k=0, verbose=1)
    w.save_function = mock_save_function
    for i, loss in enumerate(losses):
        w.on_epoch_end(i, logs={'val_loss': loss})

    file_lists = os.listdir(save_dir)

    assert len(file_lists) == 0, "Should save 0 models when save_top_k=0"

    tutils.clear_save_dir()

    # -----------------
    # CASE K=1 (2.5, epoch 4)
    w = ModelCheckpoint(save_dir,
                        save_top_k=1,
                        verbose=1,
                        prefix='test_prefix')
    w.save_function = mock_save_function
    for i, loss in enumerate(losses):
        w.on_epoch_end(i, logs={'val_loss': loss})

    file_lists = set(os.listdir(save_dir))

    assert len(file_lists) == 1, "Should save 1 model when save_top_k=1"
    assert 'test_prefix_ckpt_epoch_4.ckpt' in file_lists

    tutils.clear_save_dir()

    # -----------------
    # CASE K=2 (2.5 epoch 4, 2.8 epoch 2)
    # make sure other files don't get deleted

    w = ModelCheckpoint(save_dir, save_top_k=2, verbose=1)
    open(f'{save_dir}/other_file.ckpt', 'a').close()
    w.save_function = mock_save_function
    for i, loss in enumerate(losses):
        w.on_epoch_end(i, logs={'val_loss': loss})

    file_lists = set(os.listdir(save_dir))

    assert len(file_lists) == 3, 'Should save 2 model when save_top_k=2'
    assert '_ckpt_epoch_4.ckpt' in file_lists
    assert '_ckpt_epoch_2.ckpt' in file_lists
    assert 'other_file.ckpt' in file_lists

    tutils.clear_save_dir()

    # -----------------
    # CASE K=4 (save all 4 models)
    # multiple checkpoints within same epoch

    w = ModelCheckpoint(save_dir, save_top_k=4, verbose=1)
    w.save_function = mock_save_function
    for loss in losses:
        w.on_epoch_end(0, logs={'val_loss': loss})

    file_lists = set(os.listdir(save_dir))

    assert len(
        file_lists
    ) == 4, 'Should save all 4 models when save_top_k=4 within same epoch'

    tutils.clear_save_dir()

    # -----------------
    # CASE K=3 (save the 2nd, 3rd, 4th model)
    # multiple checkpoints within same epoch

    w = ModelCheckpoint(save_dir, save_top_k=3, verbose=1)
    w.save_function = mock_save_function
    for loss in losses:
        w.on_epoch_end(0, logs={'val_loss': loss})

    file_lists = set(os.listdir(save_dir))

    assert len(file_lists) == 3, 'Should save 3 models when save_top_k=3'
    assert '_ckpt_epoch_0_v2.ckpt' in file_lists
    assert '_ckpt_epoch_0_v1.ckpt' in file_lists
    assert '_ckpt_epoch_0.ckpt' in file_lists

    tutils.clear_save_dir()