code: def test_from_file_raises_with_missing_source(self):
      # TODO: OpError exception not propagated.
      with self.assertRaisesRegexp(
          ValueError, "Could not open missing.vcf"
      ):
          vcf_reader.VcfReader.from_file("missing.vcf", self.options)
  
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 10 for calling the WrapVcfReaderTests obj's underlying member method code with example usage: obj.test_from_file_raises_with_missing_source() without return types