46 lines
1.5 KiB
Ruby
46 lines
1.5 KiB
Ruby
# frozen_string_literal: true
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module RuboCop
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module Cop
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module Gitlab
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# This cop looks for delegations to predicate methods with `allow_nil: true` option.
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# This construct results in three possible results: true, false and nil.
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# In other words, it does not preserve the strict Boolean nature of predicate method return value.
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# This cop suggests creating a method to handle `nil` delegator and ensure only Boolean type is returned.
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#
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# @example
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# # bad
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# delegate :is_foo?, to: :bar, allow_nil: true
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#
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# # good
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# def is_foo?
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# return false unless bar
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# bar.is_foo?
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# end
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#
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# def is_foo?
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# !!bar&.is_foo?
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# end
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class DelegatePredicateMethods < RuboCop::Cop::Base
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MSG = "Using `delegate` with `allow_nil` on the following predicate methods is discouraged: %s."
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RESTRICT_ON_SEND = %i[delegate].freeze
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def_node_matcher :predicate_allow_nil_option, <<~PATTERN
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(send nil? :delegate
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(sym $_)*
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(hash <$(pair (sym :allow_nil) true) ...>)
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)
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PATTERN
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def on_send(node)
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predicate_allow_nil_option(node) do |delegated_methods, _options|
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offensive_methods = delegated_methods.select { |method| method.end_with?('?') }
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next if offensive_methods.empty?
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add_offense(node, message: format(MSG, offensive_methods.join(', ')))
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end
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end
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end
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end
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end
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end
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