class_docstr: Tests for sam.SamWriter.
code: def setUp(self):
      self.read1 = test_utils.make_read(
          bases="ACCGT",
          chrom="chr1",
          start=10,
          cigar="5M",
          mapq=50,
          quals=range(30, 35),
          name="read1",
      )
      self.read2 = test_utils.make_read(
          bases="AACCTT",
          chrom="chr2",
          start=15,
          cigar="7M",
          mapq=40,
          quals=range(20, 26),
          name="read2",
      )
      self.contigs = [
          reference_pb2.ContigInfo(name="chr1"),
          reference_pb2.ContigInfo(name="chr2"),
      ]
      self.header = reads_pb2.SamHeader()
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import itertools
  from absl.testing import absltest
  from absl.testing import parameterized
  import six
  from etils import epath
  from third_party.nucleus.io import sam
  from third_party.nucleus.io import tfrecord
  from third_party.nucleus.protos import reads_pb2
  from third_party.nucleus.protos import reference_pb2
  from third_party.nucleus.testing import test_utils
  from third_party.nucleus.util import ranges
label_desc: Use image node_id 1 for calling the ReadWriterTests obj's underlying member method code with example usage: obj.setUp() without return types