React testing library fireEvent not firing / found answer - reactjs

Question

I have an issue with using react testing library and its fireEvent function.
I want to test my component and its style after hovering.
Here it is my component written in tsx:
import React from 'react'
import { makeStyles } from '#material-ui/core'
import Paper, { PaperProps } from '#material-ui/core/Paper'
import Box from '#material-ui/core/Box'
import posed from 'react-pose'
import grey from '#material-ui/core/colors/grey'
import green from '#material-ui/core/colors/green'
import lightBlue from '#material-ui/core/colors/lightBlue'
import teal from '#material-ui/core/colors/teal'
function styleProducer(variant: BigTileProps['variant'] = 'default', color: BigTileProps['color'] = 'default'): Function {
type colrMapType = {
[k: string]: { tile: { [pr: string]: string } }
}
const colorMap: colrMapType = {
default: { tile: {} },
grey: {
tile: { background: grey[700], color: 'white' }
},
green: {
tile: { background: green[300] }
},
teal: {
tile: { background: teal[400], color: 'white' }
},
blue: {
tile: { background: lightBlue[200] }
},
}
interface variantsKeys {
small: (theme: any) => object
default: (theme: any) => object
big: (theme: any) => object
large: (theme: any) => object
}
type variantsType = {
[k in keyof variantsKeys]: variantsKeys[k]
}
const variants: variantsType = {
small: (theme: any) => ({
tile: Object.assign({
minWidth: theme.spacing(10),
height: theme.spacing(10),
background: grey[500],
position: 'relative',
'&:hover': {
cursor: 'pointer'
}
}, colorMap[color].tile),
content: {
fontSize: '2rem',
fontWeight: 'bold'
},
title: {
textTransform: 'uppercase'
},
icon: {
position: 'absolute',
top: 0,
left: 0
}
}),
default: (theme: any) => ({
tile: Object.assign({
minWidth: theme.spacing(15),
height: theme.spacing(15),
position: 'relative',
'&:hover': {
cursor: 'pointer'
}
}, colorMap[color].tile),
content: {
fontSize: '2rem',
fontWeight: 'bold'
},
title: {
textTransform: 'uppercase'
},
icon: {
position: 'absolute',
top: 0,
left: 0
}
}),
big: (theme: any) => ({
tile: Object.assign({
minWidth: theme.spacing(20),
height: theme.spacing(20),
position: 'relative',
'&:hover': {
cursor: 'pointer'
}
}, colorMap[color].tile),
content: {
fontSize: '2rem',
fontWeight: 'bold'
},
title: {
textTransform: 'uppercase'
},
icon: {
position: 'absolute',
top: 0,
left: 0
}
}),
large: (theme: any) => ({
tile: Object.assign({
minWidth: theme.spacing(25),
height: theme.spacing(25),
position: 'relative',
'&:hover': {
cursor: 'pointer'
}
}, colorMap[color].tile),
content: {
fontSize: '2rem',
fontWeight: 'bold'
},
title: {
textTransform: 'uppercase'
},
icon: {
position: 'absolute',
top: 0,
left: 0
}
})
}
return makeStyles(variants[variant])
}
type BigTileProps = {
color?: 'default' | 'grey' | 'green' | 'blue' | 'teal',
variant?: 'small' | 'default' | 'big' | 'large',
width?: string, // 15px , 10rem etc
height?: string, // 15px , 10rem etc
title?: string,
content?: string
icon?: React.FC | React.ReactElement
}
const PosedPaper = posed(Paper)({
onHover: {
scale: 1.05
},
none: {
scale: 1
}
})
const BigTile: React.FC<BigTileProps> = ({
variant = 'default',
color = 'default',
width,
height,
children,
title,
content,
icon,
...props
}) => {
const [hover, setHover] = React.useState(false)
const useStyles = styleProducer(variant, color)
const classes = useStyles()
const onHoverHandle = (bool: boolean) => () => {
setHover(bool)
}
const style = {height, width}
if (!height) delete style['height']
if (!width) delete style['width']
return (
<PosedPaper className={classes.tile} style={{ height, width }} pose={hover ? 'onHover' : 'none'} onMouseEnter={onHoverHandle(true)} onMouseLeave={onHoverHandle(false)}>
<Box className={classes.icon} p={1}>
{icon}
</Box>
<Box height="100%" width="100%" display="flex" justifyContent="center" alignItems="center" flexDirection="column">
<Box mb={1} className={classes.content}>{children ? children : content}</Box>
<div className={classes.title}>{title}</div>
</Box>
</PosedPaper>
)
}
export default BigTile
And here is my test :
it('BigTile hover check', ()=>{
const { container } = render(<BigTile />)
const elem = container.querySelector<HTMLElement>('.MuiPaper-root')
if (!elem) fail("Element is null.")
fireEvent.mouseOver(elem);
const elemAfterHover = container.querySelector<HTMLElement>('.MuiPaper-root')
if (!elemAfterHover) fail("Element after hover is null.")
console.log(elemAfterHover.style)
})
Here i cant see changed style after mouseover event. Console log shows me only transform:none
when it should be something like transform: scale(1.05).
Please help me with firing this event properly and if you have some advise to the code itself it would be great to take some advices.

Answer 1

//Answer
The event was firing every time i started the test.
To check it i just put some console.log(..) inside onHoverHandle which is firing after moseenter/leave.
Of course i didn't need to find element once again after fireEvent, becouse i had this element before. Main idea is that i needed to wait for event to end before checking for style change. So waitFor is good for that.
I read somewhere than using userEvent from '#testing-library/user-event' is better than fireEvent , so i did.
Final solution :
it('BigTile hover check.', async ()=>{
const { container } = render(<BigTile />)
const elem = container.firstChild as HTMLElement
if (!elem) fail("Element is null.")
userEvent.hover(elem);
await waitFor(() => {
expect(elem.style.transform).toEqual("scale(1.05) translateZ(0)")
})
})