Rubocop: RSpec/AggregateFailures

aggregate_failures.rb

require 'rubocop/rspec/language'

module RuboCop
  module Cop
    module RSpec
      class AggregateFailures < RuboCop::Cop::Cop
        GROUP_BLOCKS = RuboCop::RSpec::Language::ExampleGroups::ALL
        EXAMPLE_BLOCKS = RuboCop::RSpec::Language::Examples::ALL

        def on_block(node)
          method, _args, body = *node
          return unless body&.begin_type?

          _receiver, method_name, _object = *method
          return unless GROUP_BLOCKS.include?(method_name)

          unless check_node(body)
            add_offense(
              node,
              :expression,
              'Use :aggregate_failures instead of several one-liners.'
            )
          end
        end

        def autocorrect(node)
          _method, _args, body = *node
          iter = body.children.each

          first_example = loop do
            child = iter.next
            break child if oneliner?(child)
          end

          base_indent = " " * first_example.source_range.column

          replacements = [
            header_from(first_example),
            body_from(first_example, base_indent)
          ]

          last_example = nil

          loop do
            child = iter.next
            break unless oneliner?(child)
            last_example = child
            replacements << body_from(child, base_indent)
          end

          replacements << "#{base_indent}end"

          range = first_example.source_range.begin.join(
            last_example.source_range.end
          )

          replacement = replacements.join("\n")

          lambda do |corrector|
            corrector.replace(range, replacement)
          end
        end

        private

        def check_node(node)
          offenders = 0

          node.children.each do |child|
            if oneliner?(child)
              offenders += 1
            elsif example_node?(child)
              break if offenders > 1
              offenders = 0
            end
          end

          offenders < 2
        end

        def oneliner?(node)
          node&.block_type? &&
            (node.source.lines.size == 1) &&
            example_node?(node)
        end

        def example_node?(node)
          method, _args, _body = *node
          _receiver, method_name, _object = *method
          EXAMPLE_BLOCKS.include?(method_name)
        end

        def header_from(node)
          method, _args, _body = *node
          _receiver, method_name, _object = *method
          %(#{method_name} "works", :aggregate_failures do)
        end

        def body_from(node, base_indent = '')
          _method, _args, body = *node
          "#{base_indent}#{indent}#{body.source}"
        end

        def indent
          @indent ||= " " * (config.for_cop('IndentationWidth')['Width'] || 2)
        end
      end
    end
  end
end

aggregate_failures_spec.rb

require 'rubocop'
require 'rubocop/rspec/support'
require 'rubocop/cop/rspec/aggregate_failures'

describe RuboCop::Cop::RSpec::AggregateFailures, :config do
  subject(:cop) { described_class.new(config) }

  it 'rejects two one-liners in a row' do
    inspect_source(cop, ['context "request" do',
                         '  it { is_expected.to be_success }',
                         '  it { expect(response.body).to eq "OK" }',
                         'end'])
    expect(cop.offenses.size).to eq(1)
    expect(cop.messages.first).to eq('Use :aggregate_failures instead of several one-liners.')
  end

  it 'rejects two one-liners when blank lines and non-example blocks' do
    inspect_source(cop, ['context "request" do',
                         '  let(:user) { create(:user) } ',
                         '  before { get "/" }',
                         '',
                         '  it { is_expected.to be_success }',
                         '  ',
                         '      ',
                         '  it { expect(response.body).to eq "OK" }',
                         'end'])
    expect(cop.offenses.size).to eq(1)
    expect(cop.messages.first).to eq('Use :aggregate_failures instead of several one-liners.')
  end

  it 'rejects one-liners with nested context' do
    inspect_source(cop, ['context "request" do',
                         '  it { is_expected.to be_success }',
                         '  it "works" do',
                         '    expect(subject).to be_ok',
                         '  end',
                         '  it { expect(response.body).to eq "OK" }',
                         '',
                         '  context "sub-request" do',
                         '    let(:params) { "?q=1" }',
                         '    it { is_expected.to be_valid }',
                         '  end',
                         'end'])
    expect(cop.offenses).to be_empty
  end

  it 'accepts single one-liner' do
    inspect_source(cop, ['context "request" do',
                         '  it { is_expected.to be_success }',
                         'end'])
    expect(cop.offenses).to be_empty
  end

  it 'accepts one-liners separated by multiliners' do
    inspect_source(cop, ['context "request" do',
                         '  it { is_expected.to be_success }',
                         '  it "works" do',
                         '    expect(subject).to be_ok',
                         '  end',
                         '  it { expect(response.body).to eq "OK" }',
                         'end'])
    expect(cop.offenses).to be_empty
  end

  it 'handles edge cases' do
    inspect_source(cop, ['context "request" do',
                         '  include_examples "edges"',
                         '  xdescribe "POST #create" do',
                         '  end',
                         '',
                         '  pending {}',
                         'end'])
    expect(cop.offenses).to be_empty
  end

  it 'handles edge cases 2' do
    inspect_source(cop, ['context "request" do',
                         '  include_examples "edges"',
                         'end'])
    expect(cop.offenses).to be_empty
  end

  describe "#autocorrect" do
    it "corrects two one-liners" do
      new_source = autocorrect_source(
        cop,
        ['context "request" do',
         '  it { is_expected.to be_success }',
         '  it { expect(response.body).to eq "OK" }',
         'end']
      )

      expect(new_source).to eq(
        ['context "request" do',
         '  it "works", :aggregate_failures do',
         '    is_expected.to be_success',
         '    expect(response.body).to eq "OK"',
         '  end',
         'end'].join("\n")
      )
    end

    it 'corrects indented one-liners when blank lines and non-example blocks' do
      new_source = autocorrect_source(
        cop,
        ['describe "GET #index" do',
         '  context "request" do',
         '    let(:user) { create(:user) } ',
         '    before { get "/" }',
         '',
         '    it { is_expected.to be_success }',
         '      ',
         '      ',
         '    it { expect(response.body).to eq "OK" }',
         '  end',
         'end']
      )
      expect(new_source).to eq(
        ['describe "GET #index" do',
         '  context "request" do',
         '    let(:user) { create(:user) } ',
         '    before { get "/" }',
         '',
         '    it "works", :aggregate_failures do',
         '      is_expected.to be_success',
         '      expect(response.body).to eq "OK"',
         '    end',
         '  end',
         'end'].join("\n")
      )
    end

    it "corrects several groups" do
      new_source = autocorrect_source(
        cop,
        [
          'describe "GET #index" do',
          '  context "request" do',
          '    let(:user) { create(:user) } ',
          '    before { get "/" }',
          '',
          '    it { is_expected.to be_success }',
          '      ',
          '      ',
          '    it { expect(response.body).to eq "OK" }',
          '',
          '    context "sub-request", :invalid do',
          '      it { is_expected.not_to be_success }',
          '      it { expect(response.body).to eq "FAILED" }',
          '    end',
          '  end',
          'end'
        ]
      )

      expect(new_source).to eq(
        ['describe "GET #index" do',
         '  context "request" do',
         '    let(:user) { create(:user) } ',
         '    before { get "/" }',
         '',
         '    it "works", :aggregate_failures do',
         '      is_expected.to be_success',
         '      expect(response.body).to eq "OK"',
         '    end',
         '',
         '    context "sub-request", :invalid do',
         '      it "works", :aggregate_failures do',
         '        is_expected.not_to be_success',
         '        expect(response.body).to eq "FAILED"',
         '      end',
         '    end',
         '  end',
         'end'].join("\n")
      )
    end
  end
end

Thank you for sharing this!

I had to make a few small adjustments to get it to run at present date. Have a look if you too are having problems:

1. Change https://gist.github.com/palkan/ac4eb92f08d0b33f41a9330445e76fbd#file-aggregate_failures-rb-L18 to

add_offense(
  node,
  location: :expression,
  message: "Use :aggregate_failures instead of several one-liners."
)

2. Change all calls to autocorrect_source by removing the first argument cop and joining the array with join("\n").

This cop is now a part of the TestProf project: https://test-prof.evilmartians.io/#/rubocop?id=rspecaggregatefailures

And it seems to be fixed: https://github.com/palkan/test-prof/blob/master/lib/test_prof/cops/rspec/aggregate_failures.rb#L64

Thank you @palkan. I Googled this gist after watching your conference talk on youtube and completely missed the gem until later.

It's been a real pleasure following your guides and using the tools in test-prof. Much appreciated!