class_docstr: Groupwise RankingEstimator tests.
docstr: Load a static checkpoint and train estimator for 1 step.
docstr_tok: ["Load","a","static","checkpoint","and","train","estimator","for","1","step","."]
code: def test_train_from_checkpoint(self):
      """Load a static checkpoint and train estimator for 1 step."""
      self._initialize_checkpoint()
      self._estimator.train(input_fn=_train_input_fn, steps=1)
      self._assert_checkpoint(
          expected_global_step=101,
          expected_bias=[1.0, 1.0],
          expected_weights=[[1.0, 1.0], [1.9, 2.1], [3.1, 2.9]],
      )
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import os
  from absl.testing import parameterized
  import tensorflow
  from tensorflow import estimator
  from tensorflow_ranking.python import feature
  from tensorflow_ranking.python import head
  from tensorflow_ranking.python import losses
  from tensorflow_ranking.python import model
label_desc: Use image node_id 6 for calling the GroupwiseRankingEstimatorTest obj's underlying member method code with example usage: obj.test_train_from_checkpoint() without return types