Function doesNotThrow

doesNotThrow(fn, message?): void
测试断言所调用的函数不会抛出异常。
Parameters
- fn: (() => unknown)
  - - (): unknown
    - Returns unknown
- Optional message: string
  异常的消息（当测试失败时）
Returns void
Example
```
import { doesNotThrow } from 'assert';

let f = function () {
    console.log('no exception');
}
doesNotThrow(f, 'have a exception throwed.');
```