Checks if the length of a method exceeds some maximum value. Comment lines can optionally be allowed. The maximum allowed length is configurable.

You can set literals you want to fold with CountAsOne. Available are: 'array', 'hash', and 'heredoc'. Each literal will be counted as one line regardless of its actual size.

NOTE: The ExcludedMethods and IgnoredMethods configuration is deprecated and only kept for backwards compatibility. Please use AllowedMethods and AllowedPatterns instead. By default, there are no methods to allowed.

Example: CountAsOne: ['array', 'heredoc']

def m
  array = [       # +1
    1,
    2
  ]

  hash = {        # +3
    key: 'value'
  }

  <<~HEREDOC      # +1
    Heredoc
    content.
  HEREDOC
end               # 5 points

Cognitive Complexity

Cognitive Complexity is a measure of how difficult a unit of code is to intuitively understand. Unlike Cyclomatic Complexity, which determines how difficult your code will be to test, Cognitive Complexity tells you how difficult your code will be to read and comprehend.

A method's cognitive complexity is based on a few simple rules:

• Code is not considered more complex when it uses shorthand that the language provides for collapsing multiple statements into one
• Code is considered more complex for each "break in the linear flow of the code"
• Code is considered more complex when "flow breaking structures are nested"

Further reading

• Cognitive Complexity docs
• Cognitive Complexity: A new way of measuring understandability

Checks for private or protected access modifiers which are applied to a singleton method. These access modifiers do not make singleton methods private/protected. private_class_method can be used for that.

Example:

# bad

class C
  private

  def self.method
    puts 'hi'
  end
end

Example:

# good

class C
  def self.method
    puts 'hi'
  end

  private_class_method :method
end

Example:

# good

class C
  class << self
    private

    def method
      puts 'hi'
    end
  end
end

Checks for private or protected access modifiers which are applied to a singleton method. These access modifiers do not make singleton methods private/protected. private_class_method can be used for that.

Example:

# bad

class C
  private

  def self.method
    puts 'hi'
  end
end

Example:

# good

class C
  def self.method
    puts 'hi'
  end

  private_class_method :method
end

Example:

# good

class C
  class << self
    private

    def method
      puts 'hi'
    end
  end
end

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.

This cop has ContextCreatingMethods option. The default setting value is an empty array that means no method is specified. This setting is an array of methods which, when called, are known to create its own context in the module's current access context.

It also has MethodCreatingMethods option. The default setting value is an empty array that means no method is specified. This setting is an array of methods which, when called, are known to create other methods in the module's current access context.

Example:

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

  def method
  end
end

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

  def self.method3
  end
end

# bad
class Foo
  protected

  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
end

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

# good
class Foo
  private # this is not redundant (a method is defined)

  def method2
  end
end

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

  if condition?
    def method
    end
  end
end

# good
class Foo
  protected # this is not redundant (a method is defined)

  define_method(:method2) do
  end
end

Example: ContextCreatingMethods: concerning

# Lint/UselessAccessModifier:
#   ContextCreatingMethods:
#     - concerning

# good
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: MethodCreatingMethods: delegate

# Lint/UselessAccessModifier:
#   MethodCreatingMethods:
#     - delegate

# good
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

Checks for rescuing StandardError. There are two supported styles implicit and explicit. This cop will not register an offense if any error other than StandardError is specified.

Example: EnforcedStyle: explicit (default)

# `explicit` will enforce using `rescue StandardError`
# instead of `rescue`.

# bad
begin
  foo
rescue
  bar
end

# good
begin
  foo
rescue StandardError
  bar
end

# good
begin
  foo
rescue OtherError
  bar
end

# good
begin
  foo
rescue StandardError, SecurityError
  bar
end

Example: EnforcedStyle: implicit

# `implicit` will enforce using `rescue` instead of
# `rescue StandardError`.

# bad
begin
  foo
rescue StandardError
  bar
end

# good
begin
  foo
rescue
  bar
end

# good
begin
  foo
rescue OtherError
  bar
end

# good
begin
  foo
rescue StandardError, SecurityError
  bar
end

Makes sure that accessor methods are named properly. Applies to both instance and class methods.

NOTE: Offenses are only registered for methods with the expected arity. Getters (get_attribute) must have no arguments to be registered, and setters (set_attribute(value)) must have exactly one.

Example:

# bad
def set_attribute(value)
end

# good
def attribute=(value)
end

# bad
def get_attribute
end

# good
def attribute
end

# accepted, incorrect arity for getter
def get_value(attr)
end

# accepted, incorrect arity for setter
def set_value
end

This cop checks for the use of Time methods without zone.

Built on top of Ruby on Rails style guide (https://github.com/rubocop-hq/rails-style-guide#time) and the article http://danilenko.org/2012/7/6/rails_timezones/

Two styles are supported for this cop. When EnforcedStyle is 'strict' then only use of Time.zone is allowed.

When EnforcedStyle is 'flexible' then it's also allowed to use Time.intimezone.

Example: EnforcedStyle: strict

# `strict` means that `Time` should be used with `zone`.

# bad
Time.now
Time.parse('2015-03-02 19:05:37')

# bad
Time.current
Time.at(timestamp).in_time_zone

# good
Time.zone.now
Time.zone.parse('2015-03-02 19:05:37')

Example: EnforcedStyle: flexible (default)

# `flexible` allows usage of `in_time_zone` instead of `zone`.

# bad
Time.now
Time.parse('2015-03-02 19:05:37')

# good
Time.zone.now
Time.zone.parse('2015-03-02 19:05:37')

# good
Time.current
Time.at(timestamp).in_time_zone

Makes sure that accessor methods are named properly. Applies to both instance and class methods.

NOTE: Offenses are only registered for methods with the expected arity. Getters (get_attribute) must have no arguments to be registered, and setters (set_attribute(value)) must have exactly one.

Example:

# bad
def set_attribute(value)
end

# good
def attribute=(value)
end

# bad
def get_attribute
end

# good
def attribute
end

# accepted, incorrect arity for getter
def get_value(attr)
end

# accepted, incorrect arity for setter
def set_value
end

Suggests ENV.fetch for the replacement of ENV[]. ENV[] silently fails and returns nil when the environment variable is unset, which may cause unexpected behaviors when the developer forgets to set it. On the other hand, ENV.fetch raises KeyError or returns the explicitly specified default value.

Example:

# bad
ENV['X']
x = ENV['X']

# good
ENV.fetch('X')
x = ENV.fetch('X')

# also good
!ENV['X']
ENV['X'].some_method # (e.g. `.nil?`)

This cop checks for the use of Time methods without zone.

Built on top of Ruby on Rails style guide (https://github.com/rubocop-hq/rails-style-guide#time) and the article http://danilenko.org/2012/7/6/rails_timezones/

Two styles are supported for this cop. When EnforcedStyle is 'strict' then only use of Time.zone is allowed.

When EnforcedStyle is 'flexible' then it's also allowed to use Time.intimezone.

Example: EnforcedStyle: strict

# `strict` means that `Time` should be used with `zone`.

# bad
Time.now
Time.parse('2015-03-02 19:05:37')

# bad
Time.current
Time.at(timestamp).in_time_zone

# good
Time.zone.now
Time.zone.parse('2015-03-02 19:05:37')

Example: EnforcedStyle: flexible (default)

# `flexible` allows usage of `in_time_zone` instead of `zone`.

# bad
Time.now
Time.parse('2015-03-02 19:05:37')

# good
Time.zone.now
Time.zone.parse('2015-03-02 19:05:37')

# good
Time.current
Time.at(timestamp).in_time_zone

Checks for rescuing StandardError. There are two supported styles implicit and explicit. This cop will not register an offense if any error other than StandardError is specified.

Example: EnforcedStyle: explicit (default)

# `explicit` will enforce using `rescue StandardError`
# instead of `rescue`.

# bad
begin
  foo
rescue
  bar
end

# good
begin
  foo
rescue StandardError
  bar
end

# good
begin
  foo
rescue OtherError
  bar
end

# good
begin
  foo
rescue StandardError, SecurityError
  bar
end

Example: EnforcedStyle: implicit

# `implicit` will enforce using `rescue` instead of
# `rescue StandardError`.

# bad
begin
  foo
rescue StandardError
  bar
end

# good
begin
  foo
rescue
  bar
end

# good
begin
  foo
rescue OtherError
  bar
end

# good
begin
  foo
rescue StandardError, SecurityError
  bar
end