class_docstr: Tests for BigQuery Read.
class_docstr_tok: ["Tests","for","BigQuery","Read","."]
code: def test_create_reader_query(self, parallelism, bq_query_result_mock):
      bq_ds = BigQueryDatasource(
          project_id=_TEST_GCP_PROJECT_ID,
          query="SELECT * FROM mockdataset.mocktable",
      )
      read_tasks_list = bq_ds.get_read_tasks(parallelism)
      bq_query_result_mock.assert_called_once()
      assert len(read_tasks_list) == parallelism
  
imports: from unittest import mock
  import pyarrow
  import pytest
  from google.api_core import exceptions, operation
  from google.cloud import bigquery, bigquery_storage
  from google.cloud.bigquery import job
  from google.cloud.bigquery_storage_v1.types import stream
  import ray
  from ray.data.datasource import BigQueryDatasource, _BigQueryDatasink
  from ray.data.tests.conftest import *
  from ray.data.tests.mock_http_server import *
  from ray.tests.conftest import *
label_desc: Use image node_id 2 for calling the TestReadBigQuery obj's underlying member method code with example usage: obj.test_create_reader_query(parallelism, bq_query_result_mock) without return types