test.js

render() {
const { classes } = this.props;
return (
<div className={classes.container}>
<button
  className={classes.display}
  onClick={this.switch}
>
Obinna
</button>
<CSSTransition
  in={this.state.showList}
  timeout={400}
  classNames="list-transition"
  unmountOnExit
  classNames={{
  enter: classes.listTransitionEnter,
  enterActive:
  classes.listTransitionEnterActive,
  exit: classes.listTransitionExit,
  exitActive:
  classes.listTransitionExitActive,
  }}
>
<div className={classes.listBody}>
  <ul className={classes.list}>
    <li className={classes.listItem}>
    Writing JavaScript
    </li>
    <li className={classes.listItem}>
    Running
    </li>
    <li className={classes.listItem}>
    Technical Writing
    </li>
    <li className={classes.listItem}>
    Writing Clean code
    </li>
  </ul>
</div>
</CSSTransition>
</div>
);