Fix #4229 Unexpected Style/HashSyntax consistency offence

[timon]

Caching the value of force_hash_rockets? for autocorrect has a side-effect of flagging an offence every ruby19-style hash pair after the first encounter of hash with symbol value when UseHashRocketsWithSymbolValue is on, so the following code is incorrectly marked as offensive:

  scope :module => :users do
    resources :registrations, only: %i(create update destroy)
  end

I have removed memoization from force_hash_rockets? method and added a test case to check that future optimizations for autocorrect won't break the checks.

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[bquorning]

When a method takes arguments, those arguments should usually be taken into consideration when memoizing (with e.g. @memo ||= {} ; @memo[input] ||= …)

In this case I think it makes perfect sense to just remove the memoization.

/cc @Drenmi re. #3884.

[Drenmi]

🚀

[bquorning]

@bbatsov I believe I saw you recently mentioning that @rubocop-hq/rubocop-core members should merge more PRs, to get higher throughput on pending pull requests.

I merged this one. Please met me know if I did wrong.