diff --git a/CHANGELOG.md b/CHANGELOG.md
index 36e42ae..a48c14f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
+### Added
+- [Ruby] Initial rubocop gems and basic compliance added (More work to come) ([#49](https://github.com/cucumber/compatibility-kit/pull/49))
+
 ### Changed
 - [Ruby] Minimum ruby version is now bumped from 2.3 to 2.5 ([#47](https://github.com/cucumber/compatibility-kit/pull/47))
 
@@ -25,7 +28,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [11.2.0] - 2022-12-23
 ### Changed
-- Update cucumber-messages requirement from ~> 19.1, >= 19.1.2 to >= 19.1.2, < 22.0 in /ruby ([#28](https://github.com/cucumber/compatibility-kit/pull/28))
+- [Ruby] Update cucumber-messages requirement from `~> 19.1, >= 19.1.2` to `>= 19.1.2, < 22.0` ([#28](https://github.com/cucumber/compatibility-kit/pull/28))
 
 ## [11.1.0] - 2022-12-17
 
diff --git a/ruby/.rubocop.yml b/ruby/.rubocop.yml
new file mode 100644
index 0000000..42ed64e
--- /dev/null
+++ b/ruby/.rubocop.yml
@@ -0,0 +1,32 @@
+require:
+  - rubocop-performance
+  - rubocop-rake
+  - rubocop-rspec
+
+inherit_from: .rubocop_todo.yml
+
+inherit_mode:
+  merge:
+    - Exclude
+
+AllCops:
+  TargetRubyVersion: 2.5
+  NewCops: enable
+
+# Disabled on our repo's to enable polyglot-release
+# TODO: Re-enable once rubocop > 1.40
+#Gemspec/RequireMFA:
+#  Enabled: false
+
+Layout/LineLength:
+  Max: 200
+
+Style/Documentation:
+  Enabled: false
+
+Style/RegexpLiteral:
+  EnforcedStyle: slashes
+  AllowInnerSlashes: true
+
+RSpec/MessageSpies:
+  EnforcedStyle: receive
diff --git a/ruby/.rubocop_todo.yml b/ruby/.rubocop_todo.yml
new file mode 100644
index 0000000..55df7fc
--- /dev/null
+++ b/ruby/.rubocop_todo.yml
@@ -0,0 +1,317 @@
+# This configuration was generated by
+# `rubocop --auto-gen-config`
+# on 2023-10-05 09:37:18 UTC using RuboCop version 1.17.0.
+# The point is for the user to remove these configuration records
+# one by one as the offenses are removed from the code base.
+# Note that changes in the inspected code, or installation of new
+# versions of RuboCop, may require this file to be generated again.
+
+# TODO: Oct '23 -> 25 files inspected, 145 offenses detected, 96 offenses auto-correctable
+
+# Offense count: 1
+# Cop supports --auto-correct.
+Layout/EmptyLineAfterGuardClause:
+  Exclude:
+    - 'lib/messages_comparator.rb'
+
+# Offense count: 2
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle, IndentationWidth.
+# SupportedStyles: aligned, indented, indented_relative_to_receiver
+Layout/MultilineMethodCallIndentation:
+  Exclude:
+    - 'lib/cucumber-compatibility-kit.rb'
+
+# Offense count: 1
+# Cop supports --auto-correct.
+# Configuration parameters: AllowForAlignment, EnforcedStyleForExponentOperator.
+# SupportedStylesForExponentOperator: space, no_space
+Layout/SpaceAroundOperators:
+  Exclude:
+    - 'features/attachments/attachments.feature.rb'
+
+# Offense count: 1
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle.
+# SupportedStyles: require_no_space, require_space
+Layout/SpaceInLambdaLiteral:
+  Exclude:
+    - 'features/parameter-types/parameter-types.feature.rb'
+
+# Offense count: 1
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle, EnforcedStyleForEmptyBraces, SpaceBeforeBlockParameters.
+# SupportedStyles: space, no_space
+# SupportedStylesForEmptyBraces: space, no_space
+Layout/SpaceInsideBlockBraces:
+  Exclude:
+    - 'features/attachments/attachments.feature.rb'
+
+# Offense count: 4
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle.
+# SupportedStyles: space, no_space
+Layout/SpaceInsideStringInterpolation:
+  Exclude:
+    - 'spec/capture_warnings.rb'
+
+# Offense count: 1
+# Configuration parameters: AllowComments, AllowEmptyLambdas.
+Lint/EmptyBlock:
+  Exclude:
+    - 'features/minimal/minimal.feature.rb'
+
+# Offense count: 1
+# Cop supports --auto-correct.
+Lint/EnsureReturn:
+  Exclude:
+    - 'spec/capture_warnings.rb'
+
+# Offense count: 1
+# Cop supports --auto-correct.
+Lint/NonDeterministicRequireOrder:
+  Exclude:
+    - 'Rakefile'
+
+# Offense count: 1
+# Configuration parameters: AllowComments, AllowNil.
+Lint/SuppressedException:
+  Exclude:
+    - 'spec/capture_warnings.rb'
+
+# Offense count: 1
+# Cop supports --auto-correct.
+# Configuration parameters: IgnoreEmptyBlocks, AllowUnusedKeywordArguments.
+Lint/UnusedBlockArgument:
+  Exclude:
+    - 'features/unknown-parameter-type/unknown-parameter-type.feature.rb'
+
+# Offense count: 3
+# Configuration parameters: IgnoredMethods, CountRepeatedAttributes.
+Metrics/AbcSize:
+  Max: 27
+
+# Offense count: 3
+# Configuration parameters: CountComments, CountAsOne, ExcludedMethods, IgnoredMethods.
+# IgnoredMethods: refine
+Metrics/BlockLength:
+  Max: 83
+
+# Offense count: 3
+# Configuration parameters: IgnoredMethods.
+Metrics/CyclomaticComplexity:
+  Max: 11
+
+# Offense count: 3
+# Configuration parameters: CountComments, CountAsOne, ExcludedMethods, IgnoredMethods.
+Metrics/MethodLength:
+  Max: 20
+
+# Offense count: 3
+# Configuration parameters: IgnoredMethods.
+Metrics/PerceivedComplexity:
+  Max: 11
+
+# Offense count: 7
+# Configuration parameters: ExpectMatchingDefinition, CheckDefinitionPathHierarchy, Regex, IgnoreExecutableScripts, AllowedAcronyms.
+# AllowedAcronyms: CLI, DSL, ACL, API, ASCII, CPU, CSS, DNS, EOF, GUID, HTML, HTTP, HTTPS, ID, IP, JSON, LHS, QPS, RAM, RHS, RPC, SLA, SMTP, SQL, SSH, TCP, TLS, TTL, UDP, UI, UID, UUID, URI, URL, UTF8, VM, XML, XMPP, XSRF, XSS
+Naming/FileName:
+  Exclude:
+    - 'features/data-tables/data-tables.feature.rb'
+    - 'features/examples-tables/examples-tables.feature.rb'
+    - 'features/parameter-types/parameter-types.feature.rb'
+    - 'features/stack-traces/stack-traces.feature.rb'
+    - 'features/unknown-parameter-type/unknown-parameter-type.feature.rb'
+    - 'lib/cucumber-compatibility-kit.rb'
+    - 'spec/cucumber-compatibility-kit_spec.rb'
+
+# Offense count: 2
+# Configuration parameters: NamePrefix, ForbiddenPrefixes, AllowedMethods, MethodDefinitionMacros.
+# NamePrefix: is_, has_, have_
+# ForbiddenPrefixes: is_, has_, have_
+# AllowedMethods: is_a?
+# MethodDefinitionMacros: define_method, define_singleton_method
+Naming/PredicateName:
+  Exclude:
+    - 'lib/cucumber-compatibility-kit.rb'
+
+# Offense count: 2
+# Cop supports --auto-correct.
+Performance/Count:
+  Exclude:
+    - 'lib/cucumber-compatibility-kit.rb'
+
+# Offense count: 1
+# Cop supports --auto-correct.
+Performance/RedundantBlockCall:
+  Exclude:
+    - 'spec/capture_warnings.rb'
+
+# Offense count: 1
+# Cop supports --auto-correct.
+# Configuration parameters: AutoCorrect.
+Performance/StringInclude:
+  Exclude:
+    - 'spec/capture_warnings.rb'
+
+# Offense count: 1
+Performance/UnfreezeString:
+  Exclude:
+    - 'spec/capture_warnings.rb'
+
+# Offense count: 2
+# Configuration parameters: Max.
+RSpec/ExampleLength:
+  Exclude:
+    - 'spec/messages_comparator_spec.rb'
+
+# Offense count: 3
+# Configuration parameters: Include, CustomTransform, IgnoreMethods, SpecSuffixOnly.
+# Include: **/*_spec*rb*, **/spec/**/*
+RSpec/FilePath:
+  Exclude:
+    - 'spec/cucumber-compatibility-kit_spec.rb'
+    - 'spec/keys_checker_spec.rb'
+    - 'spec/messages_comparator_spec.rb'
+
+# Offense count: 1
+# Configuration parameters: AllowSubject.
+RSpec/MultipleMemoizedHelpers:
+  Max: 7
+
+# Offense count: 10
+# Configuration parameters: IgnoreSharedExamples.
+RSpec/NamedSubject:
+  Exclude:
+    - 'spec/keys_checker_spec.rb'
+    - 'spec/messages_comparator_spec.rb'
+
+# Offense count: 1
+Rake/Desc:
+  Exclude:
+    - 'Rakefile'
+
+# Offense count: 4
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle, ProceduralMethods, FunctionalMethods, IgnoredMethods, AllowBracesOnProceduralOneLiners, BracesRequiredMethods.
+# SupportedStyles: line_count_based, semantic, braces_for_chaining, always_braces
+# ProceduralMethods: benchmark, bm, bmbm, create, each_with_object, measure, new, realtime, tap, with_object
+# FunctionalMethods: let, let!, subject, watch
+# IgnoredMethods: lambda, proc, it
+Style/BlockDelimiters:
+  Exclude:
+    - 'spec/cucumber-compatibility-kit_spec.rb'
+    - 'spec/keys_checker_spec.rb'
+    - 'templates/specs.rb'
+
+# Offense count: 1
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle.
+# SupportedStyles: nested, compact
+Style/ClassAndModuleChildren:
+  Exclude:
+    - 'lib/cucumber-compatibility-kit.rb'
+
+# Offense count: 1
+# Cop supports --auto-correct.
+# Configuration parameters: Keywords.
+# Keywords: TODO, FIXME, OPTIMIZE, HACK, REVIEW, NOTE
+Style/CommentAnnotation:
+  Exclude:
+    - 'lib/shared_examples.rb'
+
+# Offense count: 1
+# Cop supports --auto-correct.
+Style/Encoding:
+  Exclude:
+    - 'Rakefile'
+
+# Offense count: 1
+# Cop supports --auto-correct.
+Style/ExpandPathArguments:
+  Exclude:
+    - 'Rakefile'
+
+# Offense count: 3
+# Cop supports --auto-correct.
+Style/GlobalStdStream:
+  Exclude:
+    - 'spec/capture_warnings.rb'
+
+# Offense count: 2
+# Cop supports --auto-correct.
+# Configuration parameters: AllowedReceivers.
+Style/HashEachMethods:
+  Exclude:
+    - 'lib/messages_comparator.rb'
+
+# Offense count: 5
+# Cop supports --auto-correct.
+Style/IfUnlessModifier:
+  Exclude:
+    - 'features/retry/retry.feature.rb'
+    - 'lib/shared_examples.rb'
+    - 'spec/capture_warnings.rb'
+
+# Offense count: 3
+# Cop supports --auto-correct.
+# Configuration parameters: IgnoredMethods.
+Style/MethodCallWithoutArgsParentheses:
+  Exclude:
+    - 'spec/messages_comparator_spec.rb'
+
+# Offense count: 1
+Style/MixinUsage:
+  Exclude:
+    - 'Rakefile'
+
+# Offense count: 2
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle, IgnoredMethods.
+# SupportedStyles: predicate, comparison
+Style/NumericPredicate:
+  Exclude:
+    - 'lib/cucumber-compatibility-kit.rb'
+
+# Offense count: 1
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle, AllowedCompactTypes.
+# SupportedStyles: compact, exploded
+Style/RaiseArgs:
+  Exclude:
+    - 'lib/cucumber-compatibility-kit.rb'
+
+# Offense count: 1
+# Cop supports --auto-correct.
+# Configuration parameters: Methods.
+Style/RedundantArgument:
+  Exclude:
+    - 'features/attachments/attachments.feature.rb'
+
+# Offense count: 1
+# Cop supports --auto-correct.
+Style/RedundantBegin:
+  Exclude:
+    - 'spec/capture_warnings.rb'
+
+# Offense count: 2
+# Cop supports --auto-correct.
+Style/RedundantSelf:
+  Exclude:
+    - 'features/attachments/attachments.feature.rb'
+
+# Offense count: 2
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle.
+# SupportedStyles: only_raise, only_fail, semantic
+Style/SignalException:
+  Exclude:
+    - 'lib/shared_examples.rb'
+    - 'spec/capture_warnings.rb'
+
+# Offense count: 1
+# Cop supports --auto-correct.
+# Configuration parameters: MinSize, WordRegex.
+# SupportedStyles: percent, brackets
+Style/WordArray:
+  EnforcedStyle: brackets
diff --git a/ruby/Gemfile b/ruby/Gemfile
index fa75df1..7f4f5e9 100644
--- a/ruby/Gemfile
+++ b/ruby/Gemfile
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 source 'https://rubygems.org'
 
 gemspec
diff --git a/ruby/Rakefile b/ruby/Rakefile
index 85e0fc7..5a08f60 100644
--- a/ruby/Rakefile
+++ b/ruby/Rakefile
@@ -1,15 +1,17 @@
 # encoding: utf-8
+# frozen_string_literal: true
+
 require 'rubygems'
 require 'bundler'
 Bundler::GemHelper.install_tasks
 
-$:.unshift File.expand_path("../lib", __FILE__)
+$LOAD_PATH.unshift File.expand_path('../lib', __FILE__)
 
 Dir['./rake/*.rb'].each do |f|
   require f
 end
 
-require "rspec/core/rake_task"
+require 'rspec/core/rake_task'
 RSpec::Core::RakeTask.new(:spec)
 
 require_relative 'spec/capture_warnings'
diff --git a/ruby/cucumber-compatibility-kit.gemspec b/ruby/cucumber-compatibility-kit.gemspec
index e1f0fcc..755cbeb 100644
--- a/ruby/cucumber-compatibility-kit.gemspec
+++ b/ruby/cucumber-compatibility-kit.gemspec
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 version = File.read(File.expand_path('VERSION', __dir__)).strip
 
 Gem::Specification.new do |s|
@@ -23,6 +25,10 @@ Gem::Specification.new do |s|
   s.add_dependency 'cucumber-messages', '>= 19.1.2', '< 22.1'
   s.add_dependency 'rake', '~> 13.0', '>= 13.0.6'
   s.add_dependency 'rspec', '~> 3.12'
+  s.add_dependency 'rubocop', '~> 1.17.0'
+  s.add_dependency 'rubocop-performance', '~> 1.7.0'
+  s.add_dependency 'rubocop-rake', '~> 0.5.0'
+  s.add_dependency 'rubocop-rspec', '~> 2.0.0'
 
   s.executables      = []
   s.rubygems_version = '>= 3.0.0'
diff --git a/ruby/features/attachments/attachments.feature.rb b/ruby/features/attachments/attachments.feature.rb
index 870a2c6..fcd3854 100644
--- a/ruby/features/attachments/attachments.feature.rb
+++ b/ruby/features/attachments/attachments.feature.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'stringio'
 
 # Cucumber-JVM needs to use a Before hook in order to create attachments
diff --git a/ruby/features/data-tables/data-tables.feature.rb b/ruby/features/data-tables/data-tables.feature.rb
index 2843acf..efb3e77 100644
--- a/ruby/features/data-tables/data-tables.feature.rb
+++ b/ruby/features/data-tables/data-tables.feature.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 When('the following table is transposed:') do |table|
   @transposed = table.transpose
 end
diff --git a/ruby/features/examples-tables/examples-tables.feature.rb b/ruby/features/examples-tables/examples-tables.feature.rb
index a7ea109..9b0bcd5 100644
--- a/ruby/features/examples-tables/examples-tables.feature.rb
+++ b/ruby/features/examples-tables/examples-tables.feature.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 Given('there are {int} cucumbers') do |initial_count|
   @count = initial_count
 end
diff --git a/ruby/features/hooks/hooks.feature.rb b/ruby/features/hooks/hooks.feature.rb
index 2e1787c..6039161 100644
--- a/ruby/features/hooks/hooks.feature.rb
+++ b/ruby/features/hooks/hooks.feature.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 def attach_or_embed(world, data, media_type)
   # Backward compatibility as the steps are also used by cucumber-ruby 3 which does not support `attach`
   world.respond_to?(:attach) ? attach(data, media_type) : embed(data, media_type)
diff --git a/ruby/features/minimal/minimal.feature.rb b/ruby/features/minimal/minimal.feature.rb
index dc32696..68adecb 100644
--- a/ruby/features/minimal/minimal.feature.rb
+++ b/ruby/features/minimal/minimal.feature.rb
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 Given('I have {int} cukes in my belly') do |cuke_count|
-end
\ No newline at end of file
+end
diff --git a/ruby/features/parameter-types/parameter-types.feature.rb b/ruby/features/parameter-types/parameter-types.feature.rb
index beaf5e9..609c57f 100644
--- a/ruby/features/parameter-types/parameter-types.feature.rb
+++ b/ruby/features/parameter-types/parameter-types.feature.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Flight
   attr_reader :from, :to
 
@@ -18,4 +20,3 @@ def initialize(from, to)
   expect(flight.to).to eq('CDG')
   expect(delay).to eq(45)
 end
-
diff --git a/ruby/features/pending/pending.feature.rb b/ruby/features/pending/pending.feature.rb
index e40f418..09e6e3f 100644
--- a/ruby/features/pending/pending.feature.rb
+++ b/ruby/features/pending/pending.feature.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 Given('an implemented step') do
   # no-op
 end
@@ -8,4 +10,4 @@
 
 Given('a step that isnt implemented yet') do
   'pending'
-end
\ No newline at end of file
+end
diff --git a/ruby/features/retry/retry.feature.rb b/ruby/features/retry/retry.feature.rb
index e43b176..51bd8fa 100644
--- a/ruby/features/retry/retry.feature.rb
+++ b/ruby/features/retry/retry.feature.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 Given('a step that always passes') do
   # no-op
 end
diff --git a/ruby/features/rules/rules.feature.rb b/ruby/features/rules/rules.feature.rb
index 11172e1..9c09585 100644
--- a/ruby/features/rules/rules.feature.rb
+++ b/ruby/features/rules/rules.feature.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 Given('there are {int} {float} coins inside') do |count, coin_type|
   expect(count).not_to be_nil
   expect(coin_type.to_s).not_to be_empty
diff --git a/ruby/features/skipped/skipped.feature.rb b/ruby/features/skipped/skipped.feature.rb
index efd9dc6..cfc19bd 100644
--- a/ruby/features/skipped/skipped.feature.rb
+++ b/ruby/features/skipped/skipped.feature.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 Before('@skip') do
   'skipped'
 end
@@ -12,4 +14,4 @@
 
 Given('a step that skips') do
   'skipped'
-end
\ No newline at end of file
+end
diff --git a/ruby/features/stack-traces/stack-traces.feature.rb b/ruby/features/stack-traces/stack-traces.feature.rb
index ccd52ea..85f2f92 100644
--- a/ruby/features/stack-traces/stack-traces.feature.rb
+++ b/ruby/features/stack-traces/stack-traces.feature.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 When('a step throws an exception') do
   raise StandardError, 'An exception is raised here'
 end
diff --git a/ruby/features/undefined/undefined.feature.rb b/ruby/features/undefined/undefined.feature.rb
index 9b9119c..e6ceea6 100644
--- a/ruby/features/undefined/undefined.feature.rb
+++ b/ruby/features/undefined/undefined.feature.rb
@@ -1,7 +1,9 @@
+# frozen_string_literal: true
+
 Given('an implemented step') do
   # no-op
 end
 
 Given('a step that we expect to be skipped') do
   # no-op
-end
\ No newline at end of file
+end
diff --git a/ruby/features/unknown-parameter-type/unknown-parameter-type.feature.rb b/ruby/features/unknown-parameter-type/unknown-parameter-type.feature.rb
index 56e01a5..4bb04d5 100644
--- a/ruby/features/unknown-parameter-type/unknown-parameter-type.feature.rb
+++ b/ruby/features/unknown-parameter-type/unknown-parameter-type.feature.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 Given('{airport} is closed because of a strike') do |airport|
   raise StandardError, 'Should not be called because airport type not defined'
-end
\ No newline at end of file
+end
diff --git a/ruby/lib/cucumber-compatibility-kit.rb b/ruby/lib/cucumber-compatibility-kit.rb
index 9c20ff8..ae0e2ce 100644
--- a/ruby/lib/cucumber-compatibility-kit.rb
+++ b/ruby/lib/cucumber-compatibility-kit.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'shared_examples'
 
 module Cucumber::CompatibilityKit
diff --git a/ruby/lib/keys_checker.rb b/ruby/lib/keys_checker.rb
index 58655e9..eaa72ba 100644
--- a/ruby/lib/keys_checker.rb
+++ b/ruby/lib/keys_checker.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 module CCK
   class KeysChecker
     def self.compare(found, expected)
diff --git a/ruby/lib/messages_comparator.rb b/ruby/lib/messages_comparator.rb
index 6463a57..d2ebe0e 100644
--- a/ruby/lib/messages_comparator.rb
+++ b/ruby/lib/messages_comparator.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative 'keys_checker'
 
 module CCK
diff --git a/ruby/lib/shared_examples.rb b/ruby/lib/shared_examples.rb
index 056abf6..a6d6ddb 100644
--- a/ruby/lib/shared_examples.rb
+++ b/ruby/lib/shared_examples.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'json'
 require 'rspec'
 require 'cucumber/messages'
@@ -10,8 +12,8 @@
   # let(:example) {  } # the name of the example to test
   # let(:messages) {  } # the messages to validate
 
-  let(:example) { raise "`example` missing: add `let(:example) { example_name }` to your spec" }
-  let(:messages) { raise "`messages` missing: add `let(:messages) { ndjson }` to your spec" }
+  let(:example) { raise '`example` missing: add `let(:example) { example_name }` to your spec' }
+  let(:messages) { raise '`messages` missing: add `let(:messages) { ndjson }` to your spec' }
 
   let(:example_path) { Cucumber::CompatibilityKit.example_path(example) }
 
diff --git a/ruby/spec/capture_warnings.rb b/ruby/spec/capture_warnings.rb
index 2315009..507cf4f 100644
--- a/ruby/spec/capture_warnings.rb
+++ b/ruby/spec/capture_warnings.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 # With thanks to @myronmarston
 # https://github.com/vcr/vcr/blob/master/spec/capture_warnings.rb
 
@@ -18,14 +19,14 @@ def report_warnings(&block)
     end
 
     # Until they fix https://bugs.ruby-lang.org/issues/10661
-    if RUBY_VERSION == "2.2.0"
+    if RUBY_VERSION == '2.2.0'
       project_warnings = project_warnings.reject { |w| w =~ /warning: possible reference to past scope/ }
     end
 
     if project_warnings.any?
       puts "#{ project_warnings.count } warnings detected"
       print_warnings('cucumber-expressions', project_warnings)
-      fail "Please remove all cucumber-expressions warnings."
+      fail 'Please remove all cucumber-expressions warnings.'
     end
 
     ensure_system_exit_if_required
@@ -56,11 +57,11 @@ def capture_error(&block)
 
   def print_warnings(type, warnings)
     puts
-    puts "-" * 30 + " #{type} warnings: " + "-" * 30
+    puts '-' * 30 + " #{type} warnings: " + '-' * 30
     puts
     puts warnings.join("\n")
     puts
-    puts "-" * 75
+    puts '-' * 75
     puts
   end
 
@@ -69,6 +70,6 @@ def ensure_system_exit_if_required
   end
 
   def capture_system_exit
-    @system_exit = $!
+    @system_exit = $ERROR_INFO
   end
 end
diff --git a/ruby/spec/cucumber-compatibility-kit_spec.rb b/ruby/spec/cucumber-compatibility-kit_spec.rb
index 86bda37..32c2151 100644
--- a/ruby/spec/cucumber-compatibility-kit_spec.rb
+++ b/ruby/spec/cucumber-compatibility-kit_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'cucumber-compatibility-kit'
 
 describe Cucumber::CompatibilityKit do
@@ -28,7 +30,7 @@
 
   describe '#examples_path' do
     it 'returns the path of the features folder' do
-      expect(Cucumber::CompatibilityKit.examples_path)
+      expect(described_class.examples_path)
         .to eq(features_path)
     end
   end
@@ -36,14 +38,14 @@
   describe '#example_path' do
     context 'with an existing example' do
       it 'returns the path of the folder of the example' do
-        expect(Cucumber::CompatibilityKit.example_path('hooks'))
+        expect(described_class.example_path('hooks'))
           .to eq("#{features_path}/hooks")
       end
     end
 
     context 'with an unexisting example' do
       it 'raises ArgumentError' do
-        expect { Cucumber::CompatibilityKit.example_path('should-not-exists') }
+        expect { described_class.example_path('should-not-exists') }
           .to raise_error(ArgumentError)
       end
     end
@@ -51,22 +53,22 @@
 
   describe '#gherkin_examples' do
     it 'returns the list of gherkin examples' do
-      expect(Cucumber::CompatibilityKit.gherkin_examples)
+      expect(described_class.gherkin_examples)
         .to match_array(gherkin_examples)
     end
   end
 
   describe '#markdown_examples' do
     it 'returns the list of markdown examples' do
-      expect(Cucumber::CompatibilityKit.markdown_examples)
+      expect(described_class.markdown_examples)
         .to match_array(markdown_examples)
     end
   end
 
   describe '#all_examples' do
     it 'returns the list of all available examples' do
-      expect(Cucumber::CompatibilityKit.all_examples)
+      expect(described_class.all_examples)
         .to match_array(gherkin_examples + markdown_examples)
     end
   end
-end
\ No newline at end of file
+end
diff --git a/ruby/spec/keys_checker_spec.rb b/ruby/spec/keys_checker_spec.rb
index 4d9b3c8..c226f21 100644
--- a/ruby/spec/keys_checker_spec.rb
+++ b/ruby/spec/keys_checker_spec.rb
@@ -1,9 +1,11 @@
+# frozen_string_literal: true
+
 require 'rspec'
 require 'cucumber/messages'
 require_relative '../lib/keys_checker'
 
 describe CCK::KeysChecker do
-  let(:subject) { CCK::KeysChecker }
+  let(:subject) { described_class }
 
   describe '#compare' do
     let(:complete) do
diff --git a/ruby/spec/messages_comparator_spec.rb b/ruby/spec/messages_comparator_spec.rb
index 48dabb0..96b08af 100644
--- a/ruby/spec/messages_comparator_spec.rb
+++ b/ruby/spec/messages_comparator_spec.rb
@@ -1,9 +1,11 @@
+# frozen_string_literal: true
+
 require 'rspec'
 require 'cucumber/messages'
 require_relative '../lib/messages_comparator'
 
 describe CCK::MessagesComparator do
-  subject() { CCK::MessagesComparator }
+  subject() { described_class }
 
   context 'when executed as part of a CI' do
     before do
diff --git a/ruby/templates/specs.rb b/ruby/templates/specs.rb
index 1500297..cc2eed5 100644
--- a/ruby/templates/specs.rb
+++ b/ruby/templates/specs.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'cucumber-compatibility-kit'
 
 describe 'Cucumber Compatibility Kit' do