Small error in test file

Hello everyone

I noticed a small mistake in `index.test.js`. Maybe it doesn't matter anymore, but I decided to open the issue. 

In this code:

```javascript
const keyup2 = createEvent('keyup')
keydown2.key = 'g'
document.dispatchEvent(keyup2)
```
`keyup2.key = 'g'` should be here, I think
