text: #!/usr/bin/env python
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  import roslib
  roslib.load_manifest('rosbag')
  
  import unittest
  import rostest
  import sys
  import time
  import subprocess
  
  class TopicCount(unittest.TestCase):
  
    def test_topic_count(self):
      # Wait while the recorder creates a bag for us to examine
      time.sleep(10.0)
  
      # Check the topic count returned by `rosbag info`
      # We could probably do this through the rosbag Python API...
      cmd = ['rosbag', 'info', 
             '/tmp/test_rosbag_record_one_publisher_two_topics.bag',
             '-y', '-k', 'topics']
      p = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
      out,err = p.communicate()
      topic_count = 0
      for l in out.decode().split('\n'):
          f = l.strip().split(': ')
          if len(f) == 2 and f[0] == '- topic':
              topic_count += 1
  
      self.assertEqual(topic_count, 2)
  
  if __name__ == '__main__':
    rostest.unitrun('test_rosbag', 'topic_count', TopicCount, sys.argv)
  