Class: RuboCop::Cop::Guardrails::NoNilSuppression

Inherits:
Base
  • Object
show all
Defined in:
lib/rubocop/cop/guardrails/no_nil_suppression.rb

Overview

Bans the safe navigation operator (‘&.`) and `try`/`try!`.

Both mechanisms silently swallow ‘nil`, hiding the question that matters: can this actually be nil? If it can’t, drop the operator and let a ‘NoMethodError` surface the real bug. If it can, that’s a concept worth naming — use an explicit predicate or a method that describes what the nil case means.

Examples:

# bad
pull_request.reviewer&.notify
pull_request.reviewer.try(:notify)

# good — if reviewer is required, let it raise
pull_request.reviewer.notify

# good — if reviewer is optional, check explicitly
pull_request.reviewer.notify if pull_request.reviewer.present?

# good — if reviewer is optional, name the business rule
pull_request.notify_reviewer

Constant Summary collapse

MSG_SAFE_NAV = 
'Do not use safe navigation (`&.`). ' \
'If `nil` is expected, use an explicit predicate (e.g. `present?`, `nil?`).'
MSG_TRY = 
'Do not use `%<method>s`. ' \
'If `nil` is expected, use an explicit predicate (e.g. `present?`, `nil?`).'

Instance Method Summary collapse

Instance Method Details

#on_csend(node) ⇒ Object 



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# File 'lib/rubocop/cop/guardrails/no_nil_suppression.rb', line 34

def on_csend(node)
  add_offense(node, message: MSG_SAFE_NAV)
end

#on_send(node) ⇒ Object 



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# File 'lib/rubocop/cop/guardrails/no_nil_suppression.rb', line 38

def on_send(node)
  if %i[try try!].include?(node.method_name)
    add_offense(node, message: format(MSG_TRY, method: node.method_name))
  end
end