code: def test_query_on_unindexed_reader_raises(self):
      window = ranges.parse_literal("chr1:10,000,000-10,000,100")
      unindexed_file = test_utils.genomics_core_testdata(
          "test_samples.vcf"
      )
      with vcf_reader.VcfReader.from_file(
          unindexed_file, self.options
      ) as reader:
          with self.assertRaisesRegexp(
              ValueError, "Cannot query without an index"
          ):
              reader.query(window)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from absl.testing import absltest
  from third_party.nucleus.io.python import vcf_reader
  from third_party.nucleus.protos import reference_pb2
  from third_party.nucleus.protos import variants_pb2
  from third_party.nucleus.testing import test_utils
  from third_party.nucleus.util import ranges
label_desc: Use image node_id 12 for calling the WrapVcfReaderTests obj's underlying member method code with example usage: obj.test_query_on_unindexed_reader_raises() without return types