Callback function in set state

[hjvvoorthuijsen]

Why

When using the useState hook of react you can set the state in two ways:

• With a direct value
• With a callback that gets the previous state as a parameter and will set the state to the returned value

The second use of the set state function doesn't work with Jooks.

What has changed

• Added a test to show the use of the callback (fails in the current version)
• Modified the useStateMock to enable the use of a callback

[antoinejaussoin]

Thanks a lot for your contribution! Will publish a new version with your change today.