code: def system(session):
      
  
      # Sanity check: Only run system tests if the environment variable is set.
      if not os.environ.get('GOOGLE_APPLICATION_CREDENTIALS', ''):
          session.skip('Credentials must be set via environment variable.')
  
      # Install all test dependencies, then install this package into the
      # virtualenv's dist-packages.
      session.install('pytest')
      session.install('-e', os.path.join('..', 'test_utils'))
      for local_dep in LOCAL_DEPS:
          session.install('-e', local_dep)
      session.install('-e', '.[pandas,fastavro]')
  
      # Run py.test against the system tests.
      session.run('py.test', '--quiet', 'tests/system/')
docs: Run the system test suite.