fix(RadioGroup): don't loop state updates

[choochootrain]

looks like this was the issue here: https://app.asana.com/0/821652619613450/929543341861746/f

componentDidUpdate gets called after handleChange on user input - this was calling handleChange again with the old value (because this.props.value isn't updated until Formbot.setState is called and propagated back down)

[codecov-io]

Codecov Report

Merging #9 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master       #9   +/-   ##
=======================================
  Coverage   69.29%   69.29%           
=======================================
  Files          10       10           
  Lines         127      127           
  Branches       20       20           
=======================================
  Hits           88       88           
  Misses         28       28           
  Partials       11       11

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[kylealwyn]

Discussed irl but documenting to also update https://github.com/sappira-inc/molekule/blob/master/src/Form/Checkbox.js#L88 to use getDerivedStateFromProps

[kylealwyn]

@choochootrain I'm also seeing a potential issue with the current logic. If a prop other than value changes, it'll always update the internal state value to the external value, which in this case would be undefined.

Propose logic to look like:

if (props.value && props.value !== state.value) {
  return {
    ...state, // cant remember if this shallow merges?
    value: props.value,
  };
}

return null;

[choochootrain]

👍 good catch, i'll update. the derived state merges like setState which is nice