tootsuite/mastodon

This cop checks if the length a class exceeds some maximum value. Comment lines can optionally be ignored. The maximum allowed length is configurable.

This cop checks if the length a class exceeds some maximum value. Comment lines can optionally be ignored. The maximum allowed length is configurable.

This cop checks if the length of a block exceeds some maximum value. Comment lines can optionally be ignored. The maximum allowed length is configurable. The cop can be configured to ignore blocks passed to certain methods.

This cop enforces empty line after guard clause

Example:

# bad
def foo
  return if need_return?
  bar
end

# good
def foo
  return if need_return?

  bar
end

# good
def foo
  return if something?
  return if something_different?

  bar
end

# also good
def foo
  if something?
    do_something
    return if need_return?
  end
end

Checks for if and unless statements that would fit on one line if written as a modifier if/unless. The maximum line length is configured in the Metrics/LineLength cop. The tab size is configured in the IndentationWidth of the Layout/Tab cop.

Example:

# bad
if condition
  do_stuff(bar)
end

unless qux.empty?
  Foo.do_something
end

# good
do_stuff(bar) if condition
Foo.do_something unless qux.empty?

Checks for if and unless statements that would fit on one line if written as a modifier if/unless. The maximum line length is configured in the Metrics/LineLength cop. The tab size is configured in the IndentationWidth of the Layout/Tab cop.

Example:

# bad
if condition
  do_stuff(bar)
end

unless qux.empty?
  Foo.do_something
end

# good
do_stuff(bar) if condition
Foo.do_something unless qux.empty?

Checks for if and unless statements that would fit on one line if written as a modifier if/unless. The maximum line length is configured in the Metrics/LineLength cop. The tab size is configured in the IndentationWidth of the Layout/Tab cop.

Example:

# bad
if condition
  do_stuff(bar)
end

unless qux.empty?
  Foo.do_something
end

# good
do_stuff(bar) if condition
Foo.do_something unless qux.empty?

Access modifiers should be declared to apply to a group of methods or inline before each method, depending on configuration.

Example: EnforcedStyle: group (default)

# bad

class Foo

  private def bar; end
  private def baz; end

end

# good

class Foo

  private

  def bar; end
  def baz; end

end

Example: EnforcedStyle: inline

# bad

class Foo

  private

  def bar; end
  def baz; end

end

# good

class Foo

  private def bar; end
  private def baz; end

end

Check that the keys, separators, and values of a multi-line hash literal are aligned according to configuration. The configuration options are:

- key (left align keys, one space before hash rockets and values)
- separator (align hash rockets and colons, right align keys)
- table (left align keys, hash rockets, and values)

The treatment of hashes passed as the last argument to a method call can also be configured. The options are:

- always_inspect
- always_ignore
- ignore_implicit (without curly braces)

Alternatively you can specify multiple allowed styles. That's done by passing a list of styles to EnforcedStyles.

Example: EnforcedHashRocketStyle: key (default)

# bad
{
  :foo => bar,
   :ba => baz
}
{
  :foo => bar,
  :ba  => baz
}

# good
{
  :foo => bar,
  :ba => baz
}

Example: EnforcedHashRocketStyle: separator

# bad
{
  :foo => bar,
  :ba => baz
}
{
  :foo => bar,
  :ba  => baz
}

# good
{
  :foo => bar,
   :ba => baz
}

Example: EnforcedHashRocketStyle: table

# bad
{
  :foo => bar,
   :ba => baz
}

# good
{
  :foo => bar,
  :ba  => baz
}

Example: EnforcedColonStyle: key (default)

# bad
{
  foo: bar,
   ba: baz
}
{
  foo: bar,
  ba:  baz
}

# good
{
  foo: bar,
  ba: baz
}

Example: EnforcedColonStyle: separator

# bad
{
  foo: bar,
  ba: baz
}

# good
{
  foo: bar,
   ba: baz
}

Example: EnforcedColonStyle: table

# bad
{
  foo: bar,
  ba: baz
}

# good
{
  foo: bar,
  ba:  baz
}

Example: EnforcedLastArgumentHashStyle: always_inspect (default)

# Inspect both implicit and explicit hashes.

# bad
do_something(foo: 1,
  bar: 2)

# bad
do_something({foo: 1,
  bar: 2})

# good
do_something(foo: 1,
             bar: 2)

# good
do_something(
  foo: 1,
  bar: 2
)

# good
do_something({foo: 1,
              bar: 2})

# good
do_something({
  foo: 1,
  bar: 2
})

Example: EnforcedLastArgumentHashStyle: always_ignore

# Ignore both implicit and explicit hashes.

# good
do_something(foo: 1,
  bar: 2)

# good
do_something({foo: 1,
  bar: 2})

Example: EnforcedLastArgumentHashStyle: ignore_implicit

# Ignore only implicit hashes.

# bad
do_something({foo: 1,
  bar: 2})

# good
do_something(foo: 1,
  bar: 2)

Example: EnforcedLastArgumentHashStyle: ignore_explicit

# Ignore only explicit hashes.

# bad
do_something(foo: 1,
  bar: 2)

# good
do_something({foo: 1,
  bar: 2})

This cop looks for has(one|many) and belongsto associations where Active Record can't automatically determine the inverse association because of a scope or the options used. Using the blog with order scope example below, traversing the a Blog's association in both directions with blog.posts.first.blog would cause the blog to be loaded from the database twice.

:inverse_of must be manually specified for Active Record to use the associated object in memory, or set to false to opt-out. Note that setting nil does not stop Active Record from trying to determine the inverse automatically, and is not considered a valid value for this.

Example:

# good
class Blog < ApplicationRecord
  has_many :posts
end

class Post < ApplicationRecord
  belongs_to :blog
end

Example:

# bad
class Blog < ApplicationRecord
  has_many :posts, -> { order(published_at: :desc) }
end

class Post < ApplicationRecord
  belongs_to :blog
end

# good
class Blog < ApplicationRecord
  has_many(:posts,
           -> { order(published_at: :desc) },
           inverse_of: :blog)
end

class Post < ApplicationRecord
  belongs_to :blog
end

# good
class Blog < ApplicationRecord
  with_options inverse_of: :blog do
    has_many :posts, -> { order(published_at: :desc) }
  end
end

class Post < ApplicationRecord
  belongs_to :blog
end

# good
# When you don't want to use the inverse association.
class Blog < ApplicationRecord
  has_many(:posts,
           -> { order(published_at: :desc) },
           inverse_of: false)
end

Example:

# bad
class Picture < ApplicationRecord
  belongs_to :imageable, polymorphic: true
end

class Employee < ApplicationRecord
  has_many :pictures, as: :imageable
end

class Product < ApplicationRecord
  has_many :pictures, as: :imageable
end

# good
class Picture < ApplicationRecord
  belongs_to :imageable, polymorphic: true
end

class Employee < ApplicationRecord
  has_many :pictures, as: :imageable, inverse_of: :imageable
end

class Product < ApplicationRecord
  has_many :pictures, as: :imageable, inverse_of: :imageable
end

Example:

# bad
# However, RuboCop can not detect this pattern...
class Physician < ApplicationRecord
  has_many :appointments
  has_many :patients, through: :appointments
end

class Appointment < ApplicationRecord
  belongs_to :physician
  belongs_to :patient
end

class Patient < ApplicationRecord
  has_many :appointments
  has_many :physicians, through: :appointments
end

# good
class Physician < ApplicationRecord
  has_many :appointments
  has_many :patients, through: :appointments
end

class Appointment < ApplicationRecord
  belongs_to :physician, inverse_of: :appointments
  belongs_to :patient, inverse_of: :appointments
end

class Patient < ApplicationRecord
  has_many :appointments
  has_many :physicians, through: :appointments
end

@see https://guides.rubyonrails.org/association_basics.html#bi-directional-associations @see https://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html#module-ActiveRecord::Associations::ClassMethods-label-Setting+Inverses

This cop enforces empty line after guard clause

Example:

# bad
def foo
  return if need_return?
  bar
end

# good
def foo
  return if need_return?

  bar
end

# good
def foo
  return if something?
  return if something_different?

  bar
end

# also good
def foo
  if something?
    do_something
    return if need_return?
  end
end

This cop checks that methods specified in the filter's only or except options are defined within the same class or module.

You can technically specify methods of superclass or methods added by mixins on the filter, but these can confuse developers. If you specify methods that are defined in other classes or modules, you should define the filter in that class or module.

If you rely on behaviour defined in the superclass actions, you must remember to invoke super in the subclass actions.

Example:

# bad
class LoginController < ApplicationController
  before_action :require_login, only: %i[index settings logout]

  def index
  end
end

# good
class LoginController < ApplicationController
  before_action :require_login, only: %i[index settings logout]

  def index
  end

  def settings
  end

  def logout
  end
end

Example:

# bad
module FooMixin
  extend ActiveSupport::Concern

  included do
    before_action proc { authenticate }, only: :foo
  end
end

# good
module FooMixin
  extend ActiveSupport::Concern

  included do
    before_action proc { authenticate }, only: :foo
  end

  def foo
    # something
  end
end

Example:

class ContentController < ApplicationController
  def update
    @content.update(content_attributes)
  end
end

class ArticlesController < ContentController
  before_action :load_article, only: [:update]

  # the cop requires this method, but it relies on behaviour defined
  # in the superclass, so needs to invoke `super`
  def update
    super
  end

  private

  def load_article
    @content = Article.find(params[:article_id])
  end
end

This cop checks that methods specified in the filter's only or except options are defined within the same class or module.

You can technically specify methods of superclass or methods added by mixins on the filter, but these can confuse developers. If you specify methods that are defined in other classes or modules, you should define the filter in that class or module.

If you rely on behaviour defined in the superclass actions, you must remember to invoke super in the subclass actions.

Example:

# bad
class LoginController < ApplicationController
  before_action :require_login, only: %i[index settings logout]

  def index
  end
end

# good
class LoginController < ApplicationController
  before_action :require_login, only: %i[index settings logout]

  def index
  end

  def settings
  end

  def logout
  end
end

Example:

# bad
module FooMixin
  extend ActiveSupport::Concern

  included do
    before_action proc { authenticate }, only: :foo
  end
end

# good
module FooMixin
  extend ActiveSupport::Concern

  included do
    before_action proc { authenticate }, only: :foo
  end

  def foo
    # something
  end
end

Example:

class ContentController < ApplicationController
  def update
    @content.update(content_attributes)
  end
end

class ArticlesController < ContentController
  before_action :load_article, only: [:update]

  # the cop requires this method, but it relies on behaviour defined
  # in the superclass, so needs to invoke `super`
  def update
    super
  end

  private

  def load_article
    @content = Article.find(params[:article_id])
  end
end

Checks for if and unless statements that would fit on one line if written as a modifier if/unless. The maximum line length is configured in the Metrics/LineLength cop. The tab size is configured in the IndentationWidth of the Layout/Tab cop.

Example:

# bad
if condition
  do_stuff(bar)
end

unless qux.empty?
  Foo.do_something
end

# good
do_stuff(bar) if condition
Foo.do_something unless qux.empty?

Checks for if and unless statements that would fit on one line if written as a modifier if/unless. The maximum line length is configured in the Metrics/LineLength cop. The tab size is configured in the IndentationWidth of the Layout/Tab cop.

Example:

# bad
if condition
  do_stuff(bar)
end

unless qux.empty?
  Foo.do_something
end

# good
do_stuff(bar) if condition
Foo.do_something unless qux.empty?

Checks for if and unless statements that would fit on one line if written as a modifier if/unless. The maximum line length is configured in the Metrics/LineLength cop. The tab size is configured in the IndentationWidth of the Layout/Tab cop.

Example:

# bad
if condition
  do_stuff(bar)
end

unless qux.empty?
  Foo.do_something
end

# good
do_stuff(bar) if condition
Foo.do_something unless qux.empty?

This cop enforces empty line after guard clause

Example:

# bad
def foo
  return if need_return?
  bar
end

# good
def foo
  return if need_return?

  bar
end

# good
def foo
  return if something?
  return if something_different?

  bar
end

# also good
def foo
  if something?
    do_something
    return if need_return?
  end
end

This cop checks method parameter names for how descriptive they are. It is highly configurable.

The MinNameLength config option takes an integer. It represents the minimum amount of characters the name must be. Its default is 3. The AllowNamesEndingInNumbers config option takes a boolean. When set to false, this cop will register offenses for names ending with numbers. Its default is false. The AllowedNames config option takes an array of whitelisted names that will never register an offense. The ForbiddenNames config option takes an array of blacklisted names that will always register an offense.

Example:

# bad
def bar(varOne, varTwo)
  varOne + varTwo
end

# With `AllowNamesEndingInNumbers` set to false
def foo(num1, num2)
  num1 * num2
end

# With `MinArgNameLength` set to number greater than 1
def baz(a, b, c)
  do_stuff(a, b, c)
end

# good
def bar(thud, fred)
  thud + fred
end

def foo(speed, distance)
  speed * distance
end

def baz(age_a, height_b, gender_c)
  do_stuff(age_a, height_b, gender_c)
end

This cop checks for redundant access modifiers, including those with no code, those which are repeated, and leading public modifiers in a class or module body. Conditionally-defined methods are considered as always being defined, and thus access modifiers guarding such methods are not redundant.

Example:

class Foo
  public # this is redundant (default access is public)

  def method
  end

  private # this is not redundant (a method is defined)
  def method2
  end

  private # this is redundant (no following methods are defined)
end

Example:

class Foo
  # The following is not redundant (conditionally defined methods are
  # considered as always defining a method)
  private

  if condition?
    def method
    end
  end

  protected # this is not redundant (method is defined)

  define_method(:method2) do
  end

  protected # this is redundant (repeated from previous modifier)

  [1,2,3].each do |i|
    define_method("foo#{i}") do
    end
  end

  # The following is redundant (methods defined on the class'
  # singleton class are not affected by the public modifier)
  public

  def self.method3
  end
end

Example:

# Lint/UselessAccessModifier:
#   ContextCreatingMethods:
#     - concerning
require 'active_support/concern'
class Foo
  concerning :Bar do
    def some_public_method
    end

    private

    def some_private_method
    end
  end

  # this is not redundant because `concerning` created its own context
  private

  def some_other_private_method
  end
end

Example:

# Lint/UselessAccessModifier:
#   MethodCreatingMethods:
#     - delegate
require 'active_support/core_ext/module/delegation'
class Foo
  # this is not redundant because `delegate` creates methods
  private

  delegate :method_a, to: :method_b
end

This cop checks whether some constant value isn't a mutable literal (e.g. array or hash).

Strict mode can be used to freeze all constants, rather than just literals. Strict mode is considered an experimental feature. It has not been updated with an exhaustive list of all methods that will produce frozen objects so there is a decent chance of getting some false positives. Luckily, there is no harm in freezing an already frozen object.

Example: EnforcedStyle: literals (default)

# bad
CONST = [1, 2, 3]

# good
CONST = [1, 2, 3].freeze

# good
CONST = <

Example: EnforcedStyle: strict

# bad
CONST = Something.new

# bad
CONST = Struct.new do
  def foo
    puts 1
  end
end

# good
CONST = Something.new.freeze

# good
CONST = Struct.new do
  def foo
    puts 1
  end
end.freeze