Add note about triggering onChange with a different value

[silvenon]

What: I added an explanation and an example how to trigger the onChange handler with fireEvent:

const comment = getByLabelText('Comment')
comment.value = 'Great advice, I love your posts!'
fireEvent.change(comment)

Why: I didn't know how to do this because I was so used to Simulate, it took me a while to figure it out. I'm not 100% sure if this is the "right" way to do it, someone please correct me if it's not.

Checklist:

• Documentation
• Tests N/A
• Ready to be merged
  
• Added myself to contributors table
  

This PR references #66.

[kentcdodds]

Cool, thanks!

[kentcdodds]

🎉 This PR is included in version 4.0.2 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀

[kelly-tock]

found this after trying to figure out a form test, I noticed when you fire change, only the target property of event is fired and not currentTarget,

example:

<input onChange={this.handleChange} value={value} data-testid="input" />

const input = getByTestId('input');

 input.value = 'testing';

 fireEvent.change(
    input
 );

in the change handler, target is defined but not current target.

any ideas?

[kelly-tock]

also as an example, if you're using flowtype or typescript,

handleChange(event: React.SyntheticEvent<HTMLInputElement>) {
    const value = event.currentTarget.value;

works, but target does not.

[kentcdodds]

That could be a bug with dom-testing-library. Care to file that?

[kelly-tock]

cool, i'll file it.

[kelly-tock]

testing-library/dom-testing-library#73