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# frozen_string_literal: true
require 'fast_spec_helper'
require 'rubocop'
require_relative '../../../../rubocop/cop/performance/readlines_each'
RSpec.describe RuboCop::Cop::Performance::ReadlinesEach, type: :rubocop do
include CopHelper
subject(:cop) { described_class.new }
let(:message) { 'Avoid `IO.readlines.each`, since it reads contents into memory in full. Use `IO.each_line` or `IO.each` instead.' }
shared_examples_for(:class_read) do |klass|
context "and it is called as a class method on #{klass}" do
# We can't use `expect_offense` here because indentation changes based on `klass`
it 'flags it as an offense' do
inspect_source "#{klass}.readlines(file_path).each { |line| puts line }"
expect(cop.offenses.map(&:cop_name)).to contain_exactly('Performance/ReadlinesEach')
end
end
context 'when just using readlines without each' do
it 'does not flag it as an offense' do
expect_no_offenses "contents = #{klass}.readlines(file_path)"
end
end
end
context 'when reading all lines using IO.readlines.each' do
%w(IO File).each do |klass|
it_behaves_like(:class_read, klass)
end
context 'and it is called as an instance method on a return value' do
it 'flags it as an offense' do
expect_offense <<~SOURCE
get_file.readlines.each { |line| puts line }
^^^^ #{message}
SOURCE
end
end
context 'and it is called as an instance method on an assigned variable' do
it 'flags it as an offense' do
expect_offense <<~SOURCE
file = File.new(path)
file.readlines.each { |line| puts line }
^^^^ #{message}
SOURCE
end
end
context 'and it is called as an instance method on a new object' do
it 'flags it as an offense' do
expect_offense <<~SOURCE
File.new(path).readlines.each { |line| puts line }
^^^^ #{message}
SOURCE
end
end
it 'autocorrects `readlines.each` to `each_line`' do
expect(autocorrect_source('obj.readlines.each { |line| line }')).to(
eq('obj.each_line { |line| line }')
)
end
end
context 'when just using readlines without each' do
it 'does not flag it as an offense' do
expect_no_offenses 'contents = my_file.readlines'
end
end
end
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