@darshan-majithiya had opened #15429 to add the hyperparameter tuning PR but it's gone stale. I'm adding this issue to see if they want to pick it back up, or if not, if someone wants to pick up where they left off in the spirit of open source 😄 
tests/providers/google/cloud/operators/test_mlengine.py
job_id='test_prediction',
                project_id='test-project',
                region=input_with_model['region'],
                data_format=input_with_model['dataFormat'],
                input_paths=input_with_model['inputPaths'],
                output_path=input_with_model['outputPath'],
                model_name=input_with_model['modelName'].split('/')[-1],
                dag=self.dag,
                task_id='test-prediction',
            )
            prediction_task.execute(None)
            mock_hook.assert_called_once_with(
                'google_cloud_default',
                None,
                impersonation_chain=None,
            )
            hook_instance.create_job.assert_called_once_with(
                'test-project', {'jobId': 'test_prediction', 'predictionInput': input_with_model}, ANY
            )
        assert http_error_code == ctx.value.resp.status
    @patch('airflow.providers.google.cloud.operators.mlengine.MLEngineHook')
    def test_failed_job_error(self, mock_hook):
        hook_instance = mock_hook.return_value
        hook_instance.create_job.return_value = {'state': 'FAILED', 'errorMessage': 'A failure message'}
        task_args = self.BATCH_PREDICTION_DEFAULT_ARGS.copy()
        task_args['uri'] = 'a uri'
        with pytest.raises(RuntimeError) as ctx:
            MLEngineStartBatchPredictionJobOperator(**task_args).execute(None)
        assert 'A failure message' == str(ctx.value)
class TestMLEngineStartTrainingJobOperator(unittest.TestCase):