def testThreadLogContextExtendLabelEmptyStrings(self):
    context = log_util.ThreadLogContext()
    self.assertEqual(context.label, '')
    with context.ExtendLabel(''):
      self.assertEqual(context.label, '')
      with context.ExtendLabel('LABEL-A'):
        self.assertEqual(context.label, 'LABEL-A ')
        with context.ExtendLabel(''):
          self.assertEqual(context.label, 'LABEL-A ')
          with context.ExtendLabel('LABEL-B'):
            self.assertEqual(context.label, 'LABEL-A LABEL-B ')
          self.assertEqual(context.label, 'LABEL-A ')
        self.assertEqual(context.label, 'LABEL-A ')
      self.assertEqual(context.label, '')
    self.assertEqual(context.label, '')
Verify ThreadLogContext.ExtendLabel behavior with empty strings.
dataset/ETHPy150Open GoogleCloudPlatform/PerfKitBenchmarker/tests/log_util_test.py/LogUtilTestCase.testThreadLogContextExtendLabelEmptyStrings