code: def test_lr_attribute_when_suggestion_invalid(tmpdir):
      """Tests learning rate finder ends before `num_training` steps."""
  
      class TestModel(BoringModel):
          def __init__(self):
              super().__init__()
              self.learning_rate = 0.123
  
      model = TestModel()
      trainer = Trainer(default_root_dir=tmpdir)
      tuner = Tuner(trainer)
      lr_finder = tuner.lr_find(
          model=model, update_attr=True, num_training=1
      )  # force insufficient data points
      assert lr_finder.suggestion() is None
      assert model.learning_rate == 0.123
  
imports: import logging
  import math
  import os
  from copy import deepcopy
  from typing import Any
  from unittest import mock
  import pytest
  import torch
  from lightning.pytorch import Trainer, seed_everything
  from lightning.pytorch.callbacks.lr_finder import LearningRateFinder
  from lightning.pytorch.demos.boring_classes import BoringModel
  from lightning.pytorch.tuner.lr_finder import _LRFinder
  from lightning.pytorch.tuner.tuning import Tuner
  from lightning.pytorch.utilities.exceptions import MisconfigurationException
  from lightning.pytorch.utilities.types import STEP_OUTPUT
  from lightning_utilities.test.warning import no_warning_call
  from tests_pytorch.helpers.datamodules import ClassifDataModule
  from tests_pytorch.helpers.runif import RunIf
  from tests_pytorch.helpers.simple_models import ClassificationModel
  from tests_pytorch.helpers.utils import getattr_recursive
label_desc: Use image node_id 16 for calling a global function with example usage: test_lr_attribute_when_suggestion_invalid(tmpdir) without return types