code: def test_keras_callback_with_no_filepath(temp_workdir):
      with open("keepsake.yaml", "w") as f:
          f.write("repository: file://.keepsake/")
  
      dense_size = 784
      learning_rate = 0.1
  
      model, x_train, y_train = _model(dense_size, learning_rate)
  
      model.fit(
          x_train,
          y_train,
          batch_size=128,
          epochs=5,
          verbose=0,
          validation_split=0.5,
          callbacks=[
              KeepsakeCallback(
                  filepath=None,
                  params={
                      "dense_size": dense_size,
                      "learning_rate": learning_rate,
                  },
                  primary_metric=("mean_absolute_error", "minimize"),
              )
          ],
      )
  
      exp_meta_paths = glob(".keepsake/metadata/experiments/*.json")
      assert len(exp_meta_paths) == 1
      with open(exp_meta_paths[0]) as f:
          exp_meta = json.load(f)
  
      assert len(exp_meta["checkpoints"]) == 5
      chkp_meta = exp_meta["checkpoints"][0]
      assert chkp_meta["path"] == ""
      assert not os.path.exists(
          ".keepsake/checkpoints/" + chkp_meta["id"] + ".tar.gz"
      )
  
file_path: keepsake/python/tests/test_keras_callback.py
imports: import json
  from glob import glob
  import tensorflow
  from tensorflow import keras
  import pytest
  import os
  from keepsake.keras_callback import KeepsakeCallback
label_desc: Use image node_id 3 for calling a global function with example usage: test_keras_callback_with_no_filepath(temp_workdir) without return types