Add failing test

[istarkov]

8.1 failing test
prehistory here

Test in first commit is new.

Changes in second commit is about that such keys also need to be deleted from this.state

[istarkov]

2 fix first failing test, it's need to change

const resetValue = (_, key) => ({[key]: undefined });

on this

const resetValue = (r, key) => ({ ...r, [key]: undefined });

[istarkov]

Third commit fixes both tests,
to emulate replaceState i've moved current state to state.props