Add autocorrection support for RSpec/IteratedExpectation for single expectations

[lovro-bikic]

Currently, RSpec/IteratedExpectation doesn't support autocorrection.

This PR adds autocorrection support for single expectations, which is the most common scenario based on real-world data.

For example, the cop will correct this:

articles.each { |a| expect(a).to be_valid }

to:

expect(articles).all to(be_valid)

Autocorrection isn't performed when to is given more than one argument, or when the block argument is used in the matcher.

real-world-rails report (75 offenses, 65 are correctable):

Report

# rubocop ../real-world-rails/apps/*/spec --only RSpec/IteratedExpectation -f clang

# ~/real-world-rails/apps/alaveteli/spec/controllers/admin_user_controller_spec.rb:395:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
Comment.find(comment_ids).each { |comment| expect(comment).to be_visible }

# ~/real-world-rails/apps/alaveteli/spec/controllers/admin_user_controller_spec.rb:423:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
Comment.find(comment_ids).each { |c| expect(c).to be_visible }

# ~/real-world-rails/apps/alaveteli/spec/controllers/outgoing_messages/delivery_statuses_controller_spec.rb:70:9: C: RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
logs.each do |log|

# ~/real-world-rails/apps/alaveteli/spec/controllers/outgoing_messages/delivery_statuses_controller_spec.rb:92:9: C: RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
logs.each do |log|

# ~/real-world-rails/apps/alaveteli/spec/controllers/statistics_controller_spec.rb:51:11: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
graph['cis_below'].each { |v| expect(v).to be_instance_of(Float) }

# ~/real-world-rails/apps/alaveteli/spec/controllers/statistics_controller_spec.rb:52:11: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
graph['cis_above'].each { |v| expect(v).to be_instance_of(Float) }

# ~/real-world-rails/apps/alaveteli/spec/models/ability_spec.rb:645:9: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
all_the_abilities.each do |ability|

# ~/real-world-rails/apps/alaveteli/spec/models/alaveteli_pro/to_do_list/list_spec.rb:19:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
described_class.new(user).items.each do |item|

# ~/real-world-rails/apps/alaveteli/spec/models/info_request_batch_spec.rb:747:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
info_request_batch.info_requests.each do |request|

# ~/real-world-rails/apps/alchemy_cms/spec/decorators/alchemy/element_editor_spec.rb:22:9: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
ingredients.each do |ingredient|

# ~/real-world-rails/apps/alonetone/spec/models/waveform_spec.rb:15:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
data.each { |sample| expect(sample).to be_kind_of(Numeric) }

# ~/real-world-rails/apps/bike_index/spec/models/bike_sticker_spec.rb:347:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
[sticker, sticker2, spokecard, spokecard2].each { |bike_sticker| expect(bike_sticker).to be_valid }

# ~/real-world-rails/apps/canvas-lms/spec/apis/v1/account_reports_api_spec.rb:102:7: C: RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
json.each do |report|

# ~/real-world-rails/apps/canvas-lms/spec/apis/v1/assignment_groups_api_spec.rb:203:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
group["assignments"].each do |assignment|

# ~/real-world-rails/apps/canvas-lms/spec/apis/v1/conversations_api_spec.rb:139:9: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
conversation["participants"].each do |user|

# ~/real-world-rails/apps/canvas-lms/spec/apis/v1/discussion_topics_api_spec.rb:864:9: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
links.each do |link|

# ~/real-world-rails/apps/canvas-lms/spec/apis/v1/discussion_topics_api_spec.rb:878:9: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
links.each do |link|

# ~/real-world-rails/apps/canvas-lms/spec/apis/v1/discussion_topics_api_spec.rb:933:9: C: RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
links.each do |link|

# ~/real-world-rails/apps/canvas-lms/spec/apis/v1/files_controller_api_spec.rb:642:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
json.pluck("url").each { |url| expect(url).to include "verifier=" }

# ~/real-world-rails/apps/canvas-lms/spec/apis/v1/files_controller_api_spec.rb:658:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
json.pluck("url").each { |url| expect(url).to include "verifier=" }

# ~/real-world-rails/apps/canvas-lms/spec/lib/job_live_events_context_spec.rb:58:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
context_values.each do |value|

# ~/real-world-rails/apps/canvas-lms/spec/models/conditional_release/stats_spec.rb:200:9: C: RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
details[:follow_on_assignments].each do |detail|

# ~/real-world-rails/apps/canvas-lms/spec/models/master_courses/master_migration_spec.rb:2917:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
copied_things.each do |copied_obj|

# ~/real-world-rails/apps/canvas-lms/spec/models/quizzes/quiz_question/answer_group_spec.rb:67:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
question_data.answers.to_a.each do |a|

# ~/real-world-rails/apps/canvas-lms/spec/models/quizzes/quiz_question/answer_parsers/answer_parser_spec_helper.rb:50:5: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
ids.each { |id| expect(id).to be_a(Integer) }

# ~/real-world-rails/apps/canvas-lms/spec/models/quizzes/quiz_question/answer_parsers/calculated_spec.rb:57:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
@question[:formulas].each do |formula|

# ~/real-world-rails/apps/canvas-lms/spec/models/sis_batch_spec.rb:750:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
@section.enrollments.not_fake.each do |e|

# ~/real-world-rails/apps/canvas-lms/spec/models/user_spec.rb:3492:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
test_student.reload.enrollments.each { |e| expect(e).to be_deleted }

# ~/real-world-rails/apps/canvas-lms/spec/selenium/admin/admin_sub_accounts_spec.rb:113:19: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
displayed ? sub_accounts.each { |account| expect(account).to be_displayed } : sub_accounts.each { |account| expect(account).not_to be_displayed }

# ~/real-world-rails/apps/canvas-lms/spec/selenium/admin/site_admin_jobs_spec.rb:51:5: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
all_jobs.each { |job| expect(job).to have_class("selected") }

# ~/real-world-rails/apps/canvas-lms/spec/selenium/courses/course_settings_spec.rb:612:5: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
ffj("#tab-details input:visible").each do |input|

# ~/real-world-rails/apps/canvas-lms/spec/selenium/helpers/announcements_common.rb:70:30: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
(expected_results > 1) ? ff(".ic-announcement-row").each { |topic| expect(topic).to include_text(expected_text) } : (expect(f(".discussionTopicIndexList .discussion-topic")).to include_text(expected_text))

# ~/real-world-rails/apps/canvas-lms/spec/selenium/helpers/eportfolios_common.rb:36:5: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
sections.each do |section|

# ~/real-world-rails/apps/canvas-lms/spec/selenium/helpers/eportfolios_common.rb:102:5: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
pages.each do |page|

# ~/real-world-rails/apps/canvas-lms/spec/selenium/helpers/legacy_announcements_common.rb:70:30: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
(expected_results > 1) ? ff(".discussionTopicIndexList .discussion-topic").each { |topic| expect(topic).to include_text(expected_text) } : (expect(f(".discussionTopicIndexList .discussion-topic")).to include_text(expected_text))

# ~/real-world-rails/apps/canvas-lms/spec/selenium/profile/profile_spec.rb:383:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
links.each do |l|

# ~/real-world-rails/apps/cm42-central/spec/helpers/projects_helper_spec.rb:8:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
point_scale_options.each do |option|

# ~/real-world-rails/apps/cm42-central/spec/helpers/projects_helper_spec.rb:18:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
iteration_length_options.each do |option|

# ~/real-world-rails/apps/cm42-central/spec/helpers/projects_helper_spec.rb:28:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
day_name_options.each do |option|

# ~/real-world-rails/apps/diaspora/spec/integration/mentioning_spec.rb:188:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
[user2, user3].each do |user|

# ~/real-world-rails/apps/diaspora/spec/integration/mentioning_spec.rb:332:11: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
[user1, user2, user3].each do |user|

# ~/real-world-rails/apps/discourse/spec/system/private_message_map_spec.rb:116:5: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
private_message_map.participants_details.each do |details|

# ~/real-world-rails/apps/foodsoft/spec/models/order_spec.rb:112:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
order.order_articles.each { |oa| expect(oa).to be_valid }

# ~/real-world-rails/apps/foodsoft/spec/models/supplier_spec.rb:36:5: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
supplier.articles.each { |a| expect(a).to have_received(:mark_as_deleted) }

# ~/real-world-rails/apps/foodsoft/spec/models/supplier_spec.rb:47:5: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
supplier.articles.each { |a| expect(a).to be_valid }

# ~/real-world-rails/apps/huginn/spec/helpers/dot_helper_spec.rb:58:9: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
@agents.each do |agent|

# ~/real-world-rails/apps/hyku/spec/tasks/rake_spec.rb:72:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
accounts.each do |account|

# ~/real-world-rails/apps/identity-idp/spec/services/backup_code_generator_spec.rb:22:5: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
codes.each do |code|

# ~/real-world-rails/apps/identity-idp/spec/services/doc_auth/lexis_nexis/responses/true_id_response_spec.rb:207:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
passed_alerts.each do |alert|

# ~/real-world-rails/apps/identity-idp/spec/services/doc_auth/lexis_nexis/responses/true_id_response_spec.rb:215:9: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
alert[:region_ref].each do |region_ref|

# ~/real-world-rails/apps/manageiq/spec/lib/vmdb/settings_spec.rb:15:11: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
value.each { |v| expect(v).to be_kind_of(Config::Options) }

# ~/real-world-rails/apps/openfoodnetwork/spec/lib/open_food_network/order_cycle_form_applicator_spec.rb:177:13: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
exchanges.each { |ex| expect(ex).to receive(:destroy) }

# ~/real-world-rails/apps/openfoodnetwork/spec/mailers/producer_mailer_spec.rb:82:5: C: RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
body_lines_including(mail, p1.name).each do |line|

# ~/real-world-rails/apps/openfoodnetwork/spec/models/spree/order_spec.rb:227:7: C: RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
order.shipments.each do |shipment|

# ~/real-world-rails/apps/openproject/spec/controllers/work_packages/moves_controller_spec.rb:397:13: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
subject.map(&:project_id).each do |id|

# ~/real-world-rails/apps/openproject/spec/controllers/work_packages/moves_controller_spec.rb:403:13: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
subject.map(&:assigned_to_id).each do |id|

# ~/real-world-rails/apps/openproject/spec/controllers/work_packages/moves_controller_spec.rb:409:13: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
subject.map(&:responsible_id).each do |id|

# ~/real-world-rails/apps/openproject/spec/controllers/work_packages/moves_controller_spec.rb:415:13: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
subject.map(&:status_id).each do |id|

# ~/real-world-rails/apps/openproject/spec/controllers/work_packages/moves_controller_spec.rb:421:13: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
subject.map(&:version_id).each do |id|

# ~/real-world-rails/apps/openproject/spec/controllers/work_packages/moves_controller_spec.rb:427:13: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
subject.map(&:start_date).each do |date|

# ~/real-world-rails/apps/openproject/spec/controllers/work_packages/moves_controller_spec.rb:433:13: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
subject.map(&:due_date).each do |date|

# ~/real-world-rails/apps/openproject/spec/services/custom_actions/update_work_package_service_spec.rb:130:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
[alter_action1, alter_action2].each do |alter_action|

# ~/real-world-rails/apps/openproject/spec/services/work_packages/delete_service_spec.rb:157:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
descendants.each do |descendant|

# ~/real-world-rails/apps/prague-server/spec/workers/calculate_organization_totals_worker_spec.rb:17:5: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
tags.each { |tag| expect(tag).to receive(:reset_redis_keys!) }

# ~/real-world-rails/apps/prague-server/spec/workers/calculate_organization_totals_worker_spec.rb:25:5: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
namespaces.each { |namespace| expect(namespace).to receive(:reset_redis_keys!) }

# ~/real-world-rails/apps/prague-server/spec/workers/calculate_organization_totals_worker_spec.rb:43:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
tags.each {|tag| expect(tag).to receive(:incrby).with(charge_amount, status: charge.status, charge_date: charge.created_at) }

# ~/real-world-rails/apps/prison-visits/spec/configuration/prison_data_spec.rb:74:9: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
enabled.each do |prison|

# ~/real-world-rails/apps/prison-visits/spec/configuration/prison_data_spec.rb:89:11: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
times.each do |time|

# ~/real-world-rails/apps/rescue-rails/spec/features/cat/cat_sort_spec.rb:56:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
ages.each do |age|

# ~/real-world-rails/apps/rescue-rails/spec/features/cat/cat_sort_spec.rb:142:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
cat_names.each do |name|

# ~/real-world-rails/apps/rescue-rails/spec/features/dog/dog_sort_spec.rb:56:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
ages.each do |age|

# ~/real-world-rails/apps/rescue-rails/spec/features/dog/dog_sort_spec.rb:142:7: C: [Correctable] RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
dog_names.each do |name|

# ~/real-world-rails/apps/sharetribe/spec/view_utils/shape_service_spec.rb:37:7: C: RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
units.each{|unit|

# ~/real-world-rails/apps/verboice/spec/models/external_service_spec.rb:67:7: C: RSpec/IteratedExpectation: Prefer using the all matcher instead of iterating over an array.
external_service.call_flows.each do |call_flow|

---

Before submitting the PR make sure the following are checked:

• Feature branch is up-to-date with master (if not - rebase it).
• Squashed related commits together.
• Added tests.
• Updated documentation.
• Added an entry to the CHANGELOG.md if the new code introduces user-observable changes.
• The build (bundle exec rake) passes (be sure to run this locally, since it may produce updated documentation that you will need to commit).

If you have created a new cop:

• Added the new cop to config/default.yml.
• The cop is configured as Enabled: pending in config/default.yml.
• The cop is configured as Enabled: true in .rubocop.yml.
• The cop documents examples of good and bad code.
• The tests assert both that bad code is reported and that good code is not reported.
• Set VersionAdded: "<<next>>" in default/config.yml.

If you have modified an existing cop's configuration options:

• Set VersionChanged: "<<next>>" in config/default.yml.

[pirj]

Fantastic, thank you!