I spent a whole day configuring Rubocop in one of our Rails project. I am here to save your day's worth of time.
Rubocop is a linter for Ruby and Rails Projects. It enforces best practices based on the guidelines outlined in the community Ruby Style Guide. Apart from reporting the problems discovered in your code, RuboCop can also automatically fix many of them for you.
Configuration for Rails
This project assumes that you have already setup rubocop in your project and have .rubocop.yml.
Step 1: Add rules to .rubocop.yml
# The behavior of RuboCop can be controlled via the .rubocop.yml
# configuration file. It makes it possible to enable/disable
# certain cops (checks) and to alter their behavior if they accept
# any parameters. The file can be placed either in your home
# directory or in some project directory.
#
# RuboCop will start looking for the configuration file in the directory
# where the inspected file is and continue its way up to the root directory.
#
inherit_from:
- '.rubocop-rails.yml'
- '.rubocop-rspec.yml'
require:
- rubocop-rails
- rubocop-rspec
AllCops:
TargetRubyVersion: 2.7
TargetRailsVersion: 6.0
Exclude:
- '**/db/migrate/*'
- '**/Gemfile.lock'
- '**/Rakefile'
- '**/rails'
- '**/vendor/**/*'
- '**/spec_helper.rb'
- 'node_modules/**/*'
- 'bin/*'
###########################################################
###################### Rubocop ############################
###########################################################
# You can find all configuration options for rubocop here: https://docs.rubocop.org/rubocop/cops_bundler.html
# ============== Layout =================
Layout/ClassStructure:
ExpectedOrder:
- module_inclusion
- constants
- association
- public_attribute_macros
- public_delegate
- macros
- initializer
- public_class_methods
- public_methods
- protected_attribute_macros
- protected_methods
- private_attribute_macros
- private_delegate
- private_methods
Layout/EmptyLineAfterMultilineCondition:
Enabled: true
Layout/EmptyLinesAroundAttributeAccessor:
Enabled: true
Layout/FirstArrayElementIndentation:
EnforcedStyle: consistent
Layout/FirstArrayElementLineBreak:
Enabled: true
Layout/FirstHashElementIndentation:
EnforcedStyle: consistent
Layout/FirstHashElementLineBreak:
Enabled: true
Layout/LineLength:
Max: 150
Exclude:
- '**/spec/**/*'
Layout/MultilineArrayBraceLayout:
EnforcedStyle: new_line
Layout/MultilineOperationIndentation:
EnforcedStyle: indented
Layout/MultilineHashBraceLayout:
EnforcedStyle: new_line
Layout/MultilineHashKeyLineBreaks:
Enabled: true
Layout/MultilineMethodCallBraceLayout:
EnforcedStyle: new_line
Layout/MultilineMethodDefinitionBraceLayout:
EnforcedStyle: new_line
Layout/SpaceAroundMethodCallOperator:
Enabled: true
Layout/SpaceInLambdaLiteral:
EnforcedStyle: require_space
Lint/AmbiguousBlockAssociation:
Exclude:
- '**/spec/**/*'
Lint/AssignmentInCondition:
AllowSafeAssignment: false
Lint/BinaryOperatorWithIdenticalOperands:
Enabled: true
Lint/DeprecatedOpenSSLConstant:
Enabled: true
Lint/DuplicateElsifCondition:
Enabled: true
Lint/DuplicateRequire:
Enabled: true
Lint/DuplicateRescueException:
Enabled: true
Lint/EmptyConditionalBody:
Enabled: true
Lint/EmptyFile:
Enabled: true
Lint/FloatComparison:
Enabled: true
Lint/MissingSuper:
Enabled: true
Lint/MixedRegexpCaptureTypes:
Enabled: true
Lint/NumberConversion:
Enabled: true
Lint/RaiseException:
Enabled: true
Lint/SelfAssignment:
Enabled: true
Lint/TrailingCommaInAttributeDeclaration:
Enabled: true
Lint/UnusedBlockArgument:
IgnoreEmptyBlocks: false
Lint/UnusedMethodArgument:
IgnoreEmptyMethods: false
Lint/UselessMethodDefinition:
Enabled: true
# ============== Metric =================
Metrics/AbcSize:
Max: 45
Metrics/BlockLength:
CountComments: false
Max: 50
Exclude:
- '**/spec/**/*'
- '**/*.rake'
- '**/factories/**/*'
- '**/config/routes.rb'
Metrics/ClassLength:
CountAsOne: ['array', 'hash']
Max: 150
Metrics/CyclomaticComplexity:
Max: 10
Metrics/MethodLength:
CountAsOne: ['array', 'hash']
Max: 30
Metrics/ModuleLength:
CountAsOne: ['array', 'hash']
Max: 250
Exclude:
- '**/spec/**/*'
Metrics/PerceivedComplexity:
Max: 10
# ============== Variable ==================
# Most of the Naming configurations are enabled by default, we should enable or disable configuration depending on what the team needs
### Example
##
# Naming/VariableNumber:
# Enabled: false
##
###
# ============== Style ================
Style/AccessorGrouping:
Enabled: true
Style/ArrayCoercion:
Enabled: true
Style/AutoResourceCleanup:
Enabled: true
Style/BisectedAttrAccessor:
Enabled: true
Style/CaseLikeIf:
Enabled: true
Style/ClassAndModuleChildren:
Enabled: false
Style/CollectionMethods:
Enabled: true
Style/CombinableLoops:
Enabled: true
Style/CommandLiteral:
EnforcedStyle: percent_x
Style/ConstantVisibility:
Enabled: true
Style/Documentation:
Enabled: false
Style/ExplicitBlockArgument:
Enabled: true
Style/GlobalStdStream:
Enabled: true
Style/HashEachMethods:
Enabled: true
Style/HashLikeCase:
Enabled: true
Style/HashTransformKeys:
Enabled: true
Style/HashTransformValues:
Enabled: true
Style/ImplicitRuntimeError:
Enabled: true
Style/InlineComment:
Enabled: true
Style/IpAddresses:
Enabled: true
Style/KeywordParametersOrder:
Enabled: true
Style/MethodCallWithArgsParentheses:
Enabled: true
Style/MissingElse:
Enabled: true
Style/MultilineMethodSignature:
Enabled: true
Style/OptionalBooleanParameter:
Enabled: true
Style/RedundantAssignment:
Enabled: true
Style/RedundantBegin:
Enabled: true
Style/RedundantFetchBlock:
Enabled: true
Style/RedundantFileExtensionInRequire:
Enabled: true
Style/RedundantSelfAssignment:
Enabled: true
Style/SingleArgumentDig:
Enabled: true
Style/StringConcatenation:
Enabled: true
Step 2: Create .rubocop-rails.yml
Above file enforces all best practices for Ruby code, now we will be adding configuration explicit for Rails.
Create .rubocop-rails.yml if you haven't already and add the following inside it:
###########################################################
#################### Rubocop Rails ########################
###########################################################
# You can find all configuration options for rubocop-rails here: https://docs.rubocop.org/rubocop-rails/cops_rails.html
Rails/ActiveRecordCallbacksOrder:
Enabled: true
Rails/AfterCommitOverride:
Enabled: true
Rails/DefaultScope:
Enabled: true
Rails/FindById:
Enabled: true
Rails/Inquiry:
Enabled: true
Rails/MailerName:
Enabled: true
Rails/MatchRoute:
Enabled: true
Rails/NegateInclude:
Enabled: true
Rails/OrderById:
Enabled: true
Rails/Pluck:
Enabled: true
Rails/PluckId:
Enabled: true
Rails/PluckInWhere:
Enabled: true
Rails/RenderInline:
Enabled: true
Rails/RenderPlainText:
Enabled: true
Rails/SaveBang:
Enabled: true
AllowImplicitReturn: false
Rails/ShortI18n:
Enabled: true
Rails/WhereExists:
Enabled: true
Rails/WhereNot:
Enabled: true
Bonus: Configuration for RSpec
NOTE: You should already have setup the rubocop-rspec gem.
Create .rubocop-rspec.yml in the root project and add the following:
###########################################################
#################### Rubocop Rspec ########################
###########################################################
# You can find all configuration options for rubocop-rspec here: https://docs.rubocop.org/rubocop-rspec/cops.html
RSpec/AnyInstance:
Enabled: false
RSpec/BeforeAfterAll:
Enabled: false
RSpec/ContextWording:
Enabled: false
RSpec/DescribeClass:
Enabled: false
RSpec/ExampleLength:
Enabled: false
RSpec/ExpectInHook:
Enabled: false
RSpec/FilePath:
Enabled: false
RSpec/InstanceVariable:
Enabled: false
RSpec/LetSetup:
Enabled: false
RSpec/MessageChain:
Enabled: false
RSpec/MessageSpies:
Enabled: false
RSpec/MultipleExpectations:
Enabled: false
RSpec/NamedSubject:
Enabled: false
RSpec/NestedGroups:
Max: 7
RSpec/SubjectStub:
Enabled: false
RSpec/VerifiedDoubles:
Enabled: false
RSpec/VoidExpect:
Enabled: false
Conclusion
You should now have fully working configuration for Rubocop in your Rails application in like 2 minutes.
Please note that, these Rubcop rules are not hard-and-fast, you should add and remove rules from the configuration files based on the decisions of your team.
Thank you for reading, see you in the next blog.
Top comments (0)