text: """Tests for data_export_util.py.
  """
  
  import StringIO
  
  from django.test import TestCase
  import vcf
  
  from main.models import Chromosome
  from main.models import Variant
  from main.models import VariantAlternate
  from main.models import VariantSet
  from main.models import VariantToVariantSet
  from main.testing_util import create_common_entities
  from utils.data_export_util import export_variant_set_as_vcf
  
  
  class TestExportVariantSetAsVcf(TestCase):
  
      def setUp(self):
          """Override.
          """
          self.common_entities = create_common_entities()
  
      def test_basic(self):
          variant_set = VariantSet.objects.create(
                  reference_genome=self.common_entities['reference_genome'],
                  label='vs1')
  
          for position in range(1, 11):
              var = Variant.objects.create(
                      type=Variant.TYPE.TRANSITION,
                      reference_genome=self.common_entities['reference_genome'],
                      chromosome=self.common_entities['chromosome'],
                      position=position,
                      ref_value='A')
  
              VariantAlternate.objects.create(
                      variant=var, alt_value='G')
  
              VariantToVariantSet.objects.create(
                      variant=var, variant_set=variant_set)
  
          output_fh = StringIO.StringIO()
  
          export_variant_set_as_vcf(variant_set, output_fh)
  
          output_fh.seek(0)
  
          reader = vcf.Reader(output_fh)
          row_count = 0
          for record in reader:
              self.assertEqual('G', record.ALT[0])
              row_count += 1
  
          self.assertEqual(10, row_count)
  