---
title: Chaijs Assertexpression Message
localeTitle: Chaijs AssertExpression消息
---
[@param](/users/param) {Mixed}表达式来测试真实性

*   [@param](/users/param) {String}消息显示错误

编写自己的测试表达式。
```
assert('foo' !== 'bar', 'foo is not bar'); 
 assert(Array.isArray(<a href='http://chaijs.com/api/assert/' target='_blank' rel='nofollow'>]), 'empty arrays are arrays'); 
```

细节：\[http://chaijs.com/api/assert/