lib/rubocop/cop/rspec/identical_equality_assertion.rb
# frozen_string_literal: true
module RuboCop
module Cop
module RSpec
# Checks for equality assertions with identical expressions on both sides.
#
# @example
# # bad
# expect(foo.bar).to eq(foo.bar)
# expect(foo.bar).to eql(foo.bar)
#
# # good
# expect(foo.bar).to eq(2)
# expect(foo.bar).to eql(2)
#
class IdenticalEqualityAssertion < Base
MSG = 'Identical expressions on both sides of the equality ' \
'may indicate a flawed test.'
RESTRICT_ON_SEND = %i[to].freeze
def on_send(node)
equality_check?(node) do |left, right|
add_offense(node) if left == right
end
end
private
# @!method equality_check?(node)
def_node_matcher :equality_check?, <<~PATTERN
(send (send nil? :expect $_) :to
{(send nil? {:eql :eq :be} $_)
(send (send nil? :be) :== $_)})
PATTERN
end
end
end
end