docs: def watch(ctx):
      """Watch the directory for changes. Automatically run tests.
      """
      vcs = ctx.obj['vcs']
  
      event_handler = TestsEventHandler(vcs)
  
      observer = Observer()
      observer.schedule(event_handler, vcs.path, recursive=True)
      observer.start()
      click.echo('Watching directory `{path}`. Use ctrl-c to stop.'.format(path=vcs.path))
      while observer.isAlive():
          observer.join(timeout=1)