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

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

NOTE: This cop also applies for Struct definitions.

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

class Foo
  ARRAY = [         # +1
    1,
    2
  ]

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

  MSG = <<~HEREDOC  # +1
    Heredoc
    content.
  HEREDOC

  foo(              # +1
    1,
    2
  )
end                 # 6 points

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 constructs you want to fold with CountAsOne. Available are: 'array', 'hash', 'heredoc', and 'method_call'. Each construct 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', 'method_call']

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

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

  <<~HEREDOC      # +1
    Heredoc
    content.
  HEREDOC

  foo(            # +1
    1,
    2
  )
end               # 6 points

Checks that the cyclomatic complexity of methods is not higher than the configured maximum. The cyclomatic complexity is the number of linearly independent paths through a method. The algorithm counts decision points and adds one.

An if statement (or unless or ?:) increases the complexity by one. An else branch does not, since it doesn't add a decision point. The && operator (or keyword and) can be converted to a nested if statement, and ||/or is shorthand for a sequence of ifs, so they also add one. Loops can be said to have an exit condition, so they add one. Blocks that are calls to builtin iteration methods (e.g. `ary.map{...}) also add one, others are ignored.

def each_child_node(*types)               # count begins: 1
  unless block_given?                     # unless: +1
    return to_enum(__method__, *types)

  children.each do |child|                # each{}: +1
    next unless child.is_a?(Node)         # unless: +1

    yield child if types.empty? ||        # if: +1, ||: +1
                   types.include?(child.type)
  end

  self
end                                       # total: 6

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

Tries to produce a complexity score that's a measure of the complexity the reader experiences when looking at a method. For that reason it considers when nodes as something that doesn't add as much complexity as an if or a &&. Except if it's one of those special case/when constructs where there's no expression after case. Then the cop treats it as an if/elsif/elsif... and lets all the when nodes count. In contrast to the CyclomaticComplexity cop, this cop considers else nodes as adding complexity.

Example:

def my_method                   # 1
  if cond                       # 1
    case var                    # 2 (0.8 + 4 * 0.2, rounded)
    when 1 then func_one
    when 2 then func_two
    when 3 then func_three
    when 4..10 then func_other
    end
  else                          # 1
    do_something until a && b   # 2
  end                           # ===
end                             # 7 complexity points

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 constructs you want to fold with CountAsOne. Available are: 'array', 'hash', 'heredoc', and 'method_call'. Each construct 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', 'method_call']

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

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

  <<~HEREDOC      # +1
    Heredoc
    content.
  HEREDOC

  foo(            # +1
    1,
    2
  )
end               # 6 points

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 constructs you want to fold with CountAsOne. Available are: 'array', 'hash', 'heredoc', and 'method_call'. Each construct 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', 'method_call']

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

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

  <<~HEREDOC      # +1
    Heredoc
    content.
  HEREDOC

  foo(            # +1
    1,
    2
  )
end               # 6 points

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 constructs you want to fold with CountAsOne. Available are: 'array', 'hash', 'heredoc', and 'method_call'. Each construct 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', 'method_call']

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

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

  <<~HEREDOC      # +1
    Heredoc
    content.
  HEREDOC

  foo(            # +1
    1,
    2
  )
end               # 6 points

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 constructs you want to fold with CountAsOne. Available are: 'array', 'hash', 'heredoc', and 'method_call'. Each construct 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', 'method_call']

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

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

  <<~HEREDOC      # +1
    Heredoc
    content.
  HEREDOC

  foo(            # +1
    1,
    2
  )
end               # 6 points

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 constructs you want to fold with CountAsOne. Available are: 'array', 'hash', 'heredoc', and 'method_call'. Each construct 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', 'method_call']

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

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

  <<~HEREDOC      # +1
    Heredoc
    content.
  HEREDOC

  foo(            # +1
    1,
    2
  )
end               # 6 points

Checks that the cyclomatic complexity of methods is not higher than the configured maximum. The cyclomatic complexity is the number of linearly independent paths through a method. The algorithm counts decision points and adds one.

An if statement (or unless or ?:) increases the complexity by one. An else branch does not, since it doesn't add a decision point. The && operator (or keyword and) can be converted to a nested if statement, and ||/or is shorthand for a sequence of ifs, so they also add one. Loops can be said to have an exit condition, so they add one. Blocks that are calls to builtin iteration methods (e.g. `ary.map{...}) also add one, others are ignored.

def each_child_node(*types)               # count begins: 1
  unless block_given?                     # unless: +1
    return to_enum(__method__, *types)

  children.each do |child|                # each{}: +1
    next unless child.is_a?(Node)         # unless: +1

    yield child if types.empty? ||        # if: +1, ||: +1
                   types.include?(child.type)
  end

  self
end                                       # total: 6

Tries to produce a complexity score that's a measure of the complexity the reader experiences when looking at a method. For that reason it considers when nodes as something that doesn't add as much complexity as an if or a &&. Except if it's one of those special case/when constructs where there's no expression after case. Then the cop treats it as an if/elsif/elsif... and lets all the when nodes count. In contrast to the CyclomaticComplexity cop, this cop considers else nodes as adding complexity.

Example:

def my_method                   # 1
  if cond                       # 1
    case var                    # 2 (0.8 + 4 * 0.2, rounded)
    when 1 then func_one
    when 2 then func_two
    when 3 then func_three
    when 4..10 then func_other
    end
  else                          # 1
    do_something until a && b   # 2
  end                           # ===
end                             # 7 complexity points

Checks that the cyclomatic complexity of methods is not higher than the configured maximum. The cyclomatic complexity is the number of linearly independent paths through a method. The algorithm counts decision points and adds one.

An if statement (or unless or ?:) increases the complexity by one. An else branch does not, since it doesn't add a decision point. The && operator (or keyword and) can be converted to a nested if statement, and ||/or is shorthand for a sequence of ifs, so they also add one. Loops can be said to have an exit condition, so they add one. Blocks that are calls to builtin iteration methods (e.g. `ary.map{...}) also add one, others are ignored.

def each_child_node(*types)               # count begins: 1
  unless block_given?                     # unless: +1
    return to_enum(__method__, *types)

  children.each do |child|                # each{}: +1
    next unless child.is_a?(Node)         # unless: +1

    yield child if types.empty? ||        # if: +1, ||: +1
                   types.include?(child.type)
  end

  self
end                                       # total: 6

Tries to produce a complexity score that's a measure of the complexity the reader experiences when looking at a method. For that reason it considers when nodes as something that doesn't add as much complexity as an if or a &&. Except if it's one of those special case/when constructs where there's no expression after case. Then the cop treats it as an if/elsif/elsif... and lets all the when nodes count. In contrast to the CyclomaticComplexity cop, this cop considers else nodes as adding complexity.

Example:

def my_method                   # 1
  if cond                       # 1
    case var                    # 2 (0.8 + 4 * 0.2, rounded)
    when 1 then func_one
    when 2 then func_two
    when 3 then func_three
    when 4..10 then func_other
    end
  else                          # 1
    do_something until a && b   # 2
  end                           # ===
end                             # 7 complexity points

Checks that the cyclomatic complexity of methods is not higher than the configured maximum. The cyclomatic complexity is the number of linearly independent paths through a method. The algorithm counts decision points and adds one.

An if statement (or unless or ?:) increases the complexity by one. An else branch does not, since it doesn't add a decision point. The && operator (or keyword and) can be converted to a nested if statement, and ||/or is shorthand for a sequence of ifs, so they also add one. Loops can be said to have an exit condition, so they add one. Blocks that are calls to builtin iteration methods (e.g. `ary.map{...}) also add one, others are ignored.

def each_child_node(*types)               # count begins: 1
  unless block_given?                     # unless: +1
    return to_enum(__method__, *types)

  children.each do |child|                # each{}: +1
    next unless child.is_a?(Node)         # unless: +1

    yield child if types.empty? ||        # if: +1, ||: +1
                   types.include?(child.type)
  end

  self
end                                       # total: 6

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

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

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

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

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

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 that the ABC size of methods is not higher than the configured maximum. The ABC size is based on assignments, branches (method calls), and conditions. See http://c2.com/cgi/wiki?AbcMetric and https://en.wikipedia.org/wiki/ABC_Software_Metric.

Interpreting ABC size:

• <= 17 satisfactory
• 18..30 unsatisfactory
• > 30 dangerous

You can have repeated "attributes" calls count as a single "branch". For this purpose, attributes are any method with no argument; no attempt is meant to distinguish actual attr_reader from other methods.

Example: CountRepeatedAttributes: false (default is true)

# `model` and `current_user`, referenced 3 times each,
 # are each counted as only 1 branch each if
 # `CountRepeatedAttributes` is set to 'false'

 def search
   @posts = model.active.visible_by(current_user)
             .search(params[:q])
   @posts = model.some_process(@posts, current_user)
   @posts = model.another_process(@posts, current_user)

   render 'pages/search/page'
 end

This cop also takes into account AllowedMethods (defaults to []) And AllowedPatterns (defaults to [])

Checks that the ABC size of methods is not higher than the configured maximum. The ABC size is based on assignments, branches (method calls), and conditions. See http://c2.com/cgi/wiki?AbcMetric and https://en.wikipedia.org/wiki/ABC_Software_Metric.

Interpreting ABC size:

• <= 17 satisfactory
• 18..30 unsatisfactory
• > 30 dangerous

You can have repeated "attributes" calls count as a single "branch". For this purpose, attributes are any method with no argument; no attempt is meant to distinguish actual attr_reader from other methods.

Example: CountRepeatedAttributes: false (default is true)

# `model` and `current_user`, referenced 3 times each,
 # are each counted as only 1 branch each if
 # `CountRepeatedAttributes` is set to 'false'

 def search
   @posts = model.active.visible_by(current_user)
             .search(params[:q])
   @posts = model.some_process(@posts, current_user)
   @posts = model.another_process(@posts, current_user)

   render 'pages/search/page'
 end

This cop also takes into account AllowedMethods (defaults to []) And AllowedPatterns (defaults to [])

Checks that the ABC size of methods is not higher than the configured maximum. The ABC size is based on assignments, branches (method calls), and conditions. See http://c2.com/cgi/wiki?AbcMetric and https://en.wikipedia.org/wiki/ABC_Software_Metric.

Interpreting ABC size:

• <= 17 satisfactory
• 18..30 unsatisfactory
• > 30 dangerous

You can have repeated "attributes" calls count as a single "branch". For this purpose, attributes are any method with no argument; no attempt is meant to distinguish actual attr_reader from other methods.

Example: CountRepeatedAttributes: false (default is true)

# `model` and `current_user`, referenced 3 times each,
 # are each counted as only 1 branch each if
 # `CountRepeatedAttributes` is set to 'false'

 def search
   @posts = model.active.visible_by(current_user)
             .search(params[:q])
   @posts = model.some_process(@posts, current_user)
   @posts = model.another_process(@posts, current_user)

   render 'pages/search/page'
 end

This cop also takes into account AllowedMethods (defaults to []) And AllowedPatterns (defaults to [])

Checks that the ABC size of methods is not higher than the configured maximum. The ABC size is based on assignments, branches (method calls), and conditions. See http://c2.com/cgi/wiki?AbcMetric and https://en.wikipedia.org/wiki/ABC_Software_Metric.

Interpreting ABC size:

• <= 17 satisfactory
• 18..30 unsatisfactory
• > 30 dangerous

You can have repeated "attributes" calls count as a single "branch". For this purpose, attributes are any method with no argument; no attempt is meant to distinguish actual attr_reader from other methods.

Example: CountRepeatedAttributes: false (default is true)

# `model` and `current_user`, referenced 3 times each,
 # are each counted as only 1 branch each if
 # `CountRepeatedAttributes` is set to 'false'

 def search
   @posts = model.active.visible_by(current_user)
             .search(params[:q])
   @posts = model.some_process(@posts, current_user)
   @posts = model.another_process(@posts, current_user)

   render 'pages/search/page'
 end

This cop also takes into account AllowedMethods (defaults to []) And AllowedPatterns (defaults to [])

Checks that the ABC size of methods is not higher than the configured maximum. The ABC size is based on assignments, branches (method calls), and conditions. See http://c2.com/cgi/wiki?AbcMetric and https://en.wikipedia.org/wiki/ABC_Software_Metric.

Interpreting ABC size:

• <= 17 satisfactory
• 18..30 unsatisfactory
• > 30 dangerous

You can have repeated "attributes" calls count as a single "branch". For this purpose, attributes are any method with no argument; no attempt is meant to distinguish actual attr_reader from other methods.

Example: CountRepeatedAttributes: false (default is true)

# `model` and `current_user`, referenced 3 times each,
 # are each counted as only 1 branch each if
 # `CountRepeatedAttributes` is set to 'false'

 def search
   @posts = model.active.visible_by(current_user)
             .search(params[:q])
   @posts = model.some_process(@posts, current_user)
   @posts = model.another_process(@posts, current_user)

   render 'pages/search/page'
 end

This cop also takes into account AllowedMethods (defaults to []) And AllowedPatterns (defaults to [])

Checks that the ABC size of methods is not higher than the configured maximum. The ABC size is based on assignments, branches (method calls), and conditions. See http://c2.com/cgi/wiki?AbcMetric and https://en.wikipedia.org/wiki/ABC_Software_Metric.

Interpreting ABC size:

• <= 17 satisfactory
• 18..30 unsatisfactory
• > 30 dangerous

You can have repeated "attributes" calls count as a single "branch". For this purpose, attributes are any method with no argument; no attempt is meant to distinguish actual attr_reader from other methods.

Example: CountRepeatedAttributes: false (default is true)

# `model` and `current_user`, referenced 3 times each,
 # are each counted as only 1 branch each if
 # `CountRepeatedAttributes` is set to 'false'

 def search
   @posts = model.active.visible_by(current_user)
             .search(params[:q])
   @posts = model.some_process(@posts, current_user)
   @posts = model.another_process(@posts, current_user)

   render 'pages/search/page'
 end

This cop also takes into account AllowedMethods (defaults to []) And AllowedPatterns (defaults to [])

Duplicated Code

Duplicated code can lead to software that is hard to understand and difficult to change. The Don't Repeat Yourself (DRY) principle states:

Every piece of knowledge must have a single, unambiguous, authoritative representation within a system.

When you violate DRY, bugs and maintenance problems are sure to follow. Duplicated code has a tendency to both continue to replicate and also to diverge (leaving bugs as two similar implementations differ in subtle ways).

Tuning

This issue has a mass of 35.

We set useful threshold defaults for the languages we support but you may want to adjust these settings based on your project guidelines.

The threshold configuration represents the minimum mass a code block must have to be analyzed for duplication. The lower the threshold, the more fine-grained the comparison.

If the engine is too easily reporting duplication, try raising the threshold. If you suspect that the engine isn't catching enough duplication, try lowering the threshold. The best setting tends to differ from language to language.

See codeclimate-duplication's documentation for more information about tuning the mass threshold in your .codeclimate.yml.

Refactorings

• Extract Method
• Extract Class
• Form Template Method
• Introduce Null Object
• Pull Up Method
• Pull Up Field
• Substitute Algorithm

Further Reading

• Don't Repeat Yourself on the C2 Wiki
• Duplicated Code on SourceMaking
• Refactoring: Improving the Design of Existing Code by Martin Fowler. Duplicated Code, p76

Duplicated Code

Duplicated code can lead to software that is hard to understand and difficult to change. The Don't Repeat Yourself (DRY) principle states:

Every piece of knowledge must have a single, unambiguous, authoritative representation within a system.

When you violate DRY, bugs and maintenance problems are sure to follow. Duplicated code has a tendency to both continue to replicate and also to diverge (leaving bugs as two similar implementations differ in subtle ways).

Tuning

This issue has a mass of 35.

We set useful threshold defaults for the languages we support but you may want to adjust these settings based on your project guidelines.

The threshold configuration represents the minimum mass a code block must have to be analyzed for duplication. The lower the threshold, the more fine-grained the comparison.

If the engine is too easily reporting duplication, try raising the threshold. If you suspect that the engine isn't catching enough duplication, try lowering the threshold. The best setting tends to differ from language to language.

See codeclimate-duplication's documentation for more information about tuning the mass threshold in your .codeclimate.yml.

Refactorings

• Extract Method
• Extract Class
• Form Template Method
• Introduce Null Object
• Pull Up Method
• Pull Up Field
• Substitute Algorithm

Further Reading

• Don't Repeat Yourself on the C2 Wiki
• Duplicated Code on SourceMaking
• Refactoring: Improving the Design of Existing Code by Martin Fowler. Duplicated Code, p76

Checks for redundant return expressions.

Example:

# These bad cases should be extended to handle methods whose body is
# if/else or a case expression with a default branch.

# bad
def test
  return something
end

# bad
def test
  one
  two
  three
  return something
end

# bad
def test
  return something if something_else
end

# good
def test
  something if something_else
end

# good
def test
  if x
  elsif y
  else
  end
end

Example: AllowMultipleReturnValues: false (default)

# bad
def test
  return x, y
end

Example: AllowMultipleReturnValues: true

# good
def test
  return x, y
end

Checks if uses of quotes match the configured preference.

Example: EnforcedStyle: single_quotes (default)

# bad
"No special symbols"
"No string interpolation"
"Just text"

# good
'No special symbols'
'No string interpolation'
'Just text'
"Wait! What's #{this}!"

Example: EnforcedStyle: double_quotes

# bad
'Just some text'
'No special chars or interpolation'

# good
"Just some text"
"No special chars or interpolation"
"Every string in #{project} uses double_quotes"

Checks for grouping of accessors in class and module bodies. By default it enforces accessors to be placed in grouped declarations, but it can be configured to enforce separating them in multiple declarations.

NOTE: If there is a method call before the accessor method it is always allowed as it might be intended like Sorbet.

Example: EnforcedStyle: grouped (default)

# bad
class Foo
  attr_reader :bar
  attr_reader :bax
  attr_reader :baz
end

# good
class Foo
  attr_reader :bar, :bax, :baz
end

# good
class Foo
  # may be intended comment for bar.
  attr_reader :bar

  sig { returns(String) }
  attr_reader :bax

  may_be_intended_annotation :baz
  attr_reader :baz
end

Example: EnforcedStyle: separated

# bad
class Foo
  attr_reader :bar, :baz
end

# good
class Foo
  attr_reader :bar
  attr_reader :baz
end

Checks for if and unless statements that would fit on one line if written as modifier if/unless. The cop also checks for modifier if/unless lines that exceed the maximum line length.

The maximum line length is configured in the Layout/LineLength cop. The tab size is configured in the IndentationWidth of the Layout/IndentationStyle cop.

One-line pattern matching is always allowed. To ensure that there are few cases where the match variable is not used, and to prevent oversights. The variable x becomes undefined and raises NameError when the following example is changed to the modifier form:

if [42] in [x]
  x # `x` is undefined when using modifier form.
end

NOTE: It is allowed when defined? argument has an undefined value, because using the modifier form causes the following incompatibility:

unless defined?(undefined_foo)
  undefined_foo = 'default_value'
end
undefined_foo # => 'default_value'

undefined_bar = 'default_value' unless defined?(undefined_bar)
undefined_bar # => nil

Example:

# bad
if condition
  do_stuff(bar)
end

unless qux.empty?
  Foo.do_something
end

do_something_with_a_long_name(arg) if long_condition_that_prevents_code_fit_on_single_line

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

if long_condition_that_prevents_code_fit_on_single_line
  do_something_with_a_long_name(arg)
end

if short_condition # a long comment that makes it too long if it were just a single line
  do_something
end

Checks if uses of quotes match the configured preference.

Example: EnforcedStyle: single_quotes (default)

# bad
"No special symbols"
"No string interpolation"
"Just text"

# good
'No special symbols'
'No string interpolation'
'Just text'
"Wait! What's #{this}!"

Example: EnforcedStyle: double_quotes

# bad
'Just some text'
'No special chars or interpolation'

# good
"Just some text"
"No special chars or interpolation"
"Every string in #{project} uses double_quotes"

Checks for trailing comma in hash literals. The configuration options are:

• consistent_comma: Requires a comma after the last item of all non-empty, multiline hash literals.
• comma: Requires a comma after the last item in a hash, but only when each item is on its own line.
• no_comma: Does not require a comma after the last item in a hash

Example: EnforcedStyleForMultiline: consistent_comma

# bad
a = { foo: 1, bar: 2, }

# good
a = { foo: 1, bar: 2 }

# good
a = {
  foo: 1, bar: 2,
  qux: 3,
}

# good
a = {
  foo: 1, bar: 2, qux: 3,
}

# good
a = {
  foo: 1,
  bar: 2,
}

Example: EnforcedStyleForMultiline: comma

# bad
a = { foo: 1, bar: 2, }

# good
a = { foo: 1, bar: 2 }

# bad
a = {
  foo: 1, bar: 2,
  qux: 3,
}

# good
a = {
  foo: 1, bar: 2,
  qux: 3
}

# bad
a = {
  foo: 1, bar: 2, qux: 3,
}

# good
a = {
  foo: 1, bar: 2, qux: 3
}

# good
a = {
  foo: 1,
  bar: 2,
}

Example: EnforcedStyleForMultiline: no_comma (default)

# bad
a = { foo: 1, bar: 2, }

# good
a = {
  foo: 1,
  bar: 2
}

Checks whether class/module/method definitions are separated by one or more empty lines.

NumberOfEmptyLines can be an integer (default is 1) or an array (e.g. [1, 2]) to specify a minimum and maximum number of empty lines permitted.

AllowAdjacentOneLineDefs configures whether adjacent one-line definitions are considered an offense.

Example: EmptyLineBetweenMethodDefs: true (default)

# checks for empty lines between method definitions.

# bad
def a
end
def b
end

Example:

# good
def a
end

def b
end

Example: EmptyLineBetweenClassDefs: true (default)

# checks for empty lines between class definitions.

# bad
class A
end
class B
end
def b
end

Example:

# good
class A
end

class B
end

def b
end

Example: EmptyLineBetweenModuleDefs: true (default)

# checks for empty lines between module definitions.

# bad
module A
end
module B
end
def b
end

Example:

# good
module A
end

module B
end

def b
end

Example: AllowAdjacentOneLineDefs: true (default)

# good
class ErrorA < BaseError; end
class ErrorB < BaseError; end
class ErrorC < BaseError; end

# good
class ErrorA < BaseError; end

class ErrorB < BaseError; end

class ErrorC < BaseError; end

Example: AllowAdjacentOneLineDefs: false

# bad
class ErrorA < BaseError; end
class ErrorB < BaseError; end
class ErrorC < BaseError; end

# good
class ErrorA < BaseError; end

class ErrorB < BaseError; end

class ErrorC < BaseError; end

Checks that the indentation method is consistent. Either tabs only or spaces only are used for indentation.

Example: EnforcedStyle: spaces (default)

# bad
# This example uses a tab to indent bar.
def foo
  bar
end

# good
# This example uses spaces to indent bar.
def foo
  bar
end

Example: EnforcedStyle: tabs

# bad
# This example uses spaces to indent bar.
def foo
  bar
end

# good
# This example uses a tab to indent bar.
def foo
  bar
end

Checks that block braces have or don't have a space before the opening brace depending on configuration.

Example: EnforcedStyle: space (default)

# bad
foo.map{ |a|
  a.bar.to_s
}

# good
foo.map { |a|
  a.bar.to_s
}

Example: EnforcedStyle: no_space

# bad
foo.map { |a|
  a.bar.to_s
}

# good
foo.map{ |a|
  a.bar.to_s
}

Example: EnforcedStyleForEmptyBraces: space (default)

# bad
7.times{}

# good
7.times {}

Example: EnforcedStyleForEmptyBraces: no_space

# bad
7.times {}

# good
7.times{}

Use next to skip iteration instead of a condition at the end.

Example: EnforcedStyle: skipmodifierifs (default)

# bad
[1, 2].each do |a|
  if a == 1
    puts a
  end
end

# good
[1, 2].each do |a|
  next unless a == 1
  puts a
end

# good
[1, 2].each do |a|
  puts a if a == 1
end

Example: EnforcedStyle: always

# With `always` all conditions at the end of an iteration needs to be
# replaced by next - with `skip_modifier_ifs` the modifier if like
# this one are ignored: `[1, 2].each { |a| puts a if a == 1 }`

# bad
[1, 2].each do |a|
  puts a if a == 1
end

# bad
[1, 2].each do |a|
  if a == 1
    puts a
  end
end

# good
[1, 2].each do |a|
  next unless a == 1
  puts a
end

Checks for usage of comparison operators (==, >, <) to test numbers as zero, positive, or negative. These can be replaced by their respective predicate methods. This cop can also be configured to do the reverse.

This cop can be customized allowed methods with AllowedMethods. By default, there are no methods to allowed.

This cop disregards #nonzero? as its value is truthy or falsey, but not true and false, and thus not always interchangeable with != 0.

This cop allows comparisons to global variables, since they are often populated with objects which can be compared with integers, but are not themselves Integer polymorphic.

Safety:

This cop is unsafe because it cannot be guaranteed that the receiver defines the predicates or can be compared to a number, which may lead to a false positive for non-standard classes.

Example: EnforcedStyle: predicate (default)

# bad
foo == 0
0 > foo
bar.baz > 0

# good
foo.zero?
foo.negative?
bar.baz.positive?

Example: EnforcedStyle: comparison

# bad
foo.zero?
foo.negative?
bar.baz.positive?

# good
foo == 0
0 > foo
bar.baz > 0

Example: AllowedMethods: [] (default) with EnforcedStyle: predicate

# bad
foo == 0
0 > foo
bar.baz > 0

Example: AllowedMethods: [==] with EnforcedStyle: predicate

# good
foo == 0

# bad
0 > foo
bar.baz > 0

Example: AllowedPatterns: [] (default) with EnforcedStyle: comparison

# bad
foo.zero?
foo.negative?
bar.baz.positive?

Example: AllowedPatterns: ['zero'] with EnforcedStyle: predicate

# good
# bad
foo.zero?

# bad
foo.negative?
bar.baz.positive?

Checks for numeric comparisons that can be replaced by a predicate method, such as receiver.length == 0, receiver.length > 0, and receiver.length != 0, receiver.length < 1 and receiver.size == 0 that can be replaced by receiver.empty? and !receiver.empty?.

NOTE: File, Tempfile, and StringIO do not have empty? so allow size == 0 and size.zero?.

Safety:

This cop is unsafe because it cannot be guaranteed that the receiver has an empty? method that is defined in terms of length. If there is a non-standard class that redefines length or empty?, the cop may register a false positive.

Example:

# bad
[1, 2, 3].length == 0
0 == "foobar".length
array.length < 1
{a: 1, b: 2}.length != 0
string.length > 0
hash.size > 0

# good
[1, 2, 3].empty?
"foobar".empty?
array.empty?
!{a: 1, b: 2}.empty?
!string.empty?
!hash.empty?

Checks whether the end keywords of method definitions are aligned properly.

Two modes are supported through the EnforcedStyleAlignWith configuration parameter. If it's set to start_of_line (which is the default), the end shall be aligned with the start of the line where the def keyword is. If it's set to def, the end shall be aligned with the def keyword.

Example: EnforcedStyleAlignWith: startofline (default)

# bad

private def foo
            end

# good

private def foo
end

Example: EnforcedStyleAlignWith: def

# bad

private def foo
            end

# good

private def foo
        end

Checks for usage of comparison operators (==, >, <) to test numbers as zero, positive, or negative. These can be replaced by their respective predicate methods. This cop can also be configured to do the reverse.

This cop can be customized allowed methods with AllowedMethods. By default, there are no methods to allowed.

This cop disregards #nonzero? as its value is truthy or falsey, but not true and false, and thus not always interchangeable with != 0.

This cop allows comparisons to global variables, since they are often populated with objects which can be compared with integers, but are not themselves Integer polymorphic.

Safety:

This cop is unsafe because it cannot be guaranteed that the receiver defines the predicates or can be compared to a number, which may lead to a false positive for non-standard classes.

Example: EnforcedStyle: predicate (default)

# bad
foo == 0
0 > foo
bar.baz > 0

# good
foo.zero?
foo.negative?
bar.baz.positive?

Example: EnforcedStyle: comparison

# bad
foo.zero?
foo.negative?
bar.baz.positive?

# good
foo == 0
0 > foo
bar.baz > 0

Example: AllowedMethods: [] (default) with EnforcedStyle: predicate

# bad
foo == 0
0 > foo
bar.baz > 0

Example: AllowedMethods: [==] with EnforcedStyle: predicate

# good
foo == 0

# bad
0 > foo
bar.baz > 0

Example: AllowedPatterns: [] (default) with EnforcedStyle: comparison

# bad
foo.zero?
foo.negative?
bar.baz.positive?

Example: AllowedPatterns: ['zero'] with EnforcedStyle: predicate

# good
# bad
foo.zero?

# bad
foo.negative?
bar.baz.positive?

Transforms usages of a method call safeguarded by a non nil check for the variable whose method is being called to safe navigation (&.). If there is a method chain, all of the methods in the chain need to be checked for safety, and all of the methods will need to be changed to use safe navigation.

The default for ConvertCodeThatCanStartToReturnNil is false. When configured to true, this will check for code in the format !foo.nil? && foo.bar. As it is written, the return of this code is limited to false and whatever the return of the method is. If this is converted to safe navigation, foo&.bar can start returning nil as well as what the method returns.

The default for MaxChainLength is 2 We have limited the cop to not register an offense for method chains that exceed this option is set.

Safety:

Autocorrection is unsafe because if a value is false, the resulting code will have different behavior or raise an error.

x = false
x && x.foo  # return false
x&.foo      # raises NoMethodError

Example:

# bad
foo.bar if foo
foo.bar.baz if foo
foo.bar(param1, param2) if foo
foo.bar { |e| e.something } if foo
foo.bar(param) { |e| e.something } if foo

foo.bar if !foo.nil?
foo.bar unless !foo
foo.bar unless foo.nil?

foo && foo.bar
foo && foo.bar.baz
foo && foo.bar(param1, param2)
foo && foo.bar { |e| e.something }
foo && foo.bar(param) { |e| e.something }

foo ? foo.bar : nil
foo.nil? ? nil : foo.bar
!foo.nil? ? foo.bar : nil
!foo ? nil : foo.bar

# good
foo&.bar
foo&.bar&.baz
foo&.bar(param1, param2)
foo&.bar { |e| e.something }
foo&.bar(param) { |e| e.something }
foo && foo.bar.baz.qux # method chain with more than 2 methods
foo && foo.nil? # method that `nil` responds to

# Method calls that do not use `.`
foo && foo < bar
foo < bar if foo

# When checking `foo&.empty?` in a conditional, `foo` being `nil` will actually
# do the opposite of what the author intends.
foo && foo.empty?

# This could start returning `nil` as well as the return of the method
foo.nil? || foo.bar
!foo || foo.bar

# Methods that are used on assignment, arithmetic operation or
# comparison should not be converted to use safe navigation
foo.baz = bar if foo
foo.baz + bar if foo
foo.bar > 2 if foo

Looks for trailing whitespace in the source code.

Example:

# The line in this example contains spaces after the 0.
# bad
x = 0

# The line in this example ends directly after the 0.
# good
x = 0

Example: AllowInHeredoc: false (default)

# The line in this example contains spaces after the 0.
# bad
code = <<~RUBY
  x = 0
RUBY

# ok
code = <<~RUBY
  x = 0 #{}
RUBY

# good
trailing_whitespace = ' '
code = <<~RUBY
  x = 0#{trailing_whitespace}
RUBY

Example: AllowInHeredoc: true

# The line in this example contains spaces after the 0.
# good
code = <<~RUBY
  x = 0
RUBY

Checks for redundant safe navigation calls. Use cases where a constant, named in camel case for classes and modules is nil are rare, and an offense is not detected when the receiver is a constant. The detection also applies to literal receivers, except for nil.

For all receivers, the instance_of?, kind_of?, is_a?, eql?, respond_to?, and equal? methods are checked by default. These are customizable with AllowedMethods option.

The AllowedMethods option specifies nil-safe methods, in other words, it is a method that is allowed to skip safe navigation. Note that the AllowedMethod option is not an option that specifies methods for which to suppress (allow) this cop's check.

In the example below, the safe navigation operator (&.) is unnecessary because NilClass has methods like respond_to? and is_a?.

Safety:

This cop is unsafe, because autocorrection can change the return type of the expression. An offending expression that previously could return nil will be autocorrected to never return nil.

Example:

# bad
CamelCaseConst&.do_something

# bad
do_something if attrs&.respond_to?(:[])

# good
do_something if attrs.respond_to?(:[])

# bad
while node&.is_a?(BeginNode)
  node = node.parent
end

# good
CamelCaseConst.do_something

# good
while node.is_a?(BeginNode)
  node = node.parent
end

# good - without `&.` this will always return `true`
foo&.respond_to?(:to_a)

# bad - for `nil`s conversion methods return default values for the type
foo&.to_h || {}
foo&.to_h { |k, v| [k, v] } || {}
foo&.to_a || []
foo&.to_i || 0
foo&.to_f || 0.0
foo&.to_s || ''

# good
foo.to_h
foo.to_h { |k, v| [k, v] }
foo.to_a
foo.to_i
foo.to_f
foo.to_s

Example: AllowedMethods: [nilsafemethod]

# bad
do_something if attrs&.nil_safe_method(:[])

# good
do_something if attrs.nil_safe_method(:[])
do_something if attrs&.not_nil_safe_method(:[])

Checks for every useless assignment to local variable in every scope. The basic idea for this cop was from the warning of ruby -cw:

assigned but unused variable - foo

Currently this cop has advanced logic that detects unreferenced reassignments and properly handles varied cases such as branch, loop, rescue, ensure, etc.

NOTE: Given the assignment foo = 1, bar = 2, removing unused variables can lead to a syntax error, so this case is not autocorrected.

Safety:

This cop's autocorrection is unsafe because removing assignment from operator assignment can cause NameError if this assignment has been used to declare local variable. For example, replacing a ||= 1 to a || 1 may cause "undefined local variable or method `a' for main:Object (NameError)".

Example:

# bad

def some_method
  some_var = 1
  do_something
end

Example:

# good

def some_method
  some_var = 1
  do_something(some_var)
end

Checks if uses of quotes match the configured preference.

Example: EnforcedStyle: single_quotes (default)

# bad
"No special symbols"
"No string interpolation"
"Just text"

# good
'No special symbols'
'No string interpolation'
'Just text'
"Wait! What's #{this}!"

Example: EnforcedStyle: double_quotes

# bad
'Just some text'
'No special chars or interpolation'

# good
"Just some text"
"No special chars or interpolation"
"Every string in #{project} uses double_quotes"

Checks if uses of quotes match the configured preference.

Example: EnforcedStyle: single_quotes (default)

# bad
"No special symbols"
"No string interpolation"
"Just text"

# good
'No special symbols'
'No string interpolation'
'Just text'
"Wait! What's #{this}!"

Example: EnforcedStyle: double_quotes

# bad
'Just some text'
'No special chars or interpolation'

# good
"Just some text"
"No special chars or interpolation"
"Every string in #{project} uses double_quotes"

Checks the indentation of the first key in a hash literal where the opening brace and the first key are on separate lines. The other keys' indentations are handled by the HashAlignment cop.

By default, Hash literals that are arguments in a method call with parentheses, and where the opening curly brace of the hash is on the same line as the opening parenthesis of the method call, shall have their first key indented one step (two spaces) more than the position inside the opening parenthesis.

Other hash literals shall have their first key indented one step more than the start of the line where the opening curly brace is.

This default style is called 'specialinsideparentheses'. Alternative styles are 'consistent' and 'align_braces'. Here are examples:

Example: EnforcedStyle: specialinsideparentheses (default)

# The `special_inside_parentheses` style enforces that the first key
# in a hash literal where the opening brace and the first key are on
# separate lines is indented one step (two spaces) more than the
# position inside the opening parentheses.

# bad
hash = {
  key: :value
}
and_in_a_method_call({
  no: :difference
                     })
takes_multi_pairs_hash(x: {
  a: 1,
  b: 2
},
                       y: {
                         c: 1,
                         d: 2
                       })

# good
special_inside_parentheses
hash = {
  key: :value
}
but_in_a_method_call({
                       its_like: :this
                     })
takes_multi_pairs_hash(x: {
                         a: 1,
                         b: 2
                       },
                       y: {
                         c: 1,
                         d: 2
                       })

Example: EnforcedStyle: consistent

# The `consistent` style enforces that the first key in a hash
# literal where the opening brace and the first key are on
# separate lines is indented the same as a hash literal which is not
# defined inside a method call.

# bad
hash = {
  key: :value
}
but_in_a_method_call({
                       its_like: :this
                      })

# good
hash = {
  key: :value
}
and_in_a_method_call({
  no: :difference
})

Example: EnforcedStyle: align_braces

# The `align_brackets` style enforces that the opening and closing
# braces are indented to the same position.

# bad
and_now_for_something = {
                          completely: :different
}
takes_multi_pairs_hash(x: {
  a: 1,
  b: 2
},
                        y: {
                             c: 1,
                             d: 2
                           })

# good
and_now_for_something = {
                          completely: :different
                        }
takes_multi_pairs_hash(x: {
                            a: 1,
                            b: 2
                          },
                       y: {
                            c: 1,
                            d: 2
                          })

Checks that the indentation method is consistent. Either tabs only or spaces only are used for indentation.

Example: EnforcedStyle: spaces (default)

# bad
# This example uses a tab to indent bar.
def foo
  bar
end

# good
# This example uses spaces to indent bar.
def foo
  bar
end

Example: EnforcedStyle: tabs

# bad
# This example uses spaces to indent bar.
def foo
  bar
end

# good
# This example uses a tab to indent bar.
def foo
  bar
end

Checks for usage of comparison operators (==, >, <) to test numbers as zero, positive, or negative. These can be replaced by their respective predicate methods. This cop can also be configured to do the reverse.

This cop can be customized allowed methods with AllowedMethods. By default, there are no methods to allowed.

This cop disregards #nonzero? as its value is truthy or falsey, but not true and false, and thus not always interchangeable with != 0.

This cop allows comparisons to global variables, since they are often populated with objects which can be compared with integers, but are not themselves Integer polymorphic.

Safety:

This cop is unsafe because it cannot be guaranteed that the receiver defines the predicates or can be compared to a number, which may lead to a false positive for non-standard classes.

Example: EnforcedStyle: predicate (default)

# bad
foo == 0
0 > foo
bar.baz > 0

# good
foo.zero?
foo.negative?
bar.baz.positive?

Example: EnforcedStyle: comparison

# bad
foo.zero?
foo.negative?
bar.baz.positive?

# good
foo == 0
0 > foo
bar.baz > 0

Example: AllowedMethods: [] (default) with EnforcedStyle: predicate

# bad
foo == 0
0 > foo
bar.baz > 0

Example: AllowedMethods: [==] with EnforcedStyle: predicate

# good
foo == 0

# bad
0 > foo
bar.baz > 0

Example: AllowedPatterns: [] (default) with EnforcedStyle: comparison

# bad
foo.zero?
foo.negative?
bar.baz.positive?

Example: AllowedPatterns: ['zero'] with EnforcedStyle: predicate

# good
# bad
foo.zero?

# bad
foo.negative?
bar.baz.positive?

Checks if uses of quotes match the configured preference.

Example: EnforcedStyle: single_quotes (default)

# bad
"No special symbols"
"No string interpolation"
"Just text"

# good
'No special symbols'
'No string interpolation'
'Just text'
"Wait! What's #{this}!"

Example: EnforcedStyle: double_quotes

# bad
'Just some text'
'No special chars or interpolation'

# good
"Just some text"
"No special chars or interpolation"
"Every string in #{project} uses double_quotes"

Checks that quotes inside string, symbol, and regexp interpolations match the configured preference.

Example: EnforcedStyle: single_quotes (default)

# bad
string = "Tests #{success ? "PASS" : "FAIL"}"
symbol = :"Tests #{success ? "PASS" : "FAIL"}"
heredoc = <<~TEXT
  Tests #{success ? "PASS" : "FAIL"}
TEXT
regexp = /Tests #{success ? "PASS" : "FAIL"}/

# good
string = "Tests #{success ? 'PASS' : 'FAIL'}"
symbol = :"Tests #{success ? 'PASS' : 'FAIL'}"
heredoc = <<~TEXT
  Tests #{success ? 'PASS' : 'FAIL'}
TEXT
regexp = /Tests #{success ? 'PASS' : 'FAIL'}/

Example: EnforcedStyle: double_quotes

# bad
string = "Tests #{success ? 'PASS' : 'FAIL'}"
symbol = :"Tests #{success ? 'PASS' : 'FAIL'}"
heredoc = <<~TEXT
  Tests #{success ? 'PASS' : 'FAIL'}
TEXT
regexp = /Tests #{success ? 'PASS' : 'FAIL'}/

# good
string = "Tests #{success ? "PASS" : "FAIL"}"
symbol = :"Tests #{success ? "PASS" : "FAIL"}"
heredoc = <<~TEXT
  Tests #{success ? "PASS" : "FAIL"}
TEXT
regexp = /Tests #{success ? "PASS" : "FAIL"}/

Checks that quotes inside string, symbol, and regexp interpolations match the configured preference.

Example: EnforcedStyle: single_quotes (default)

# bad
string = "Tests #{success ? "PASS" : "FAIL"}"
symbol = :"Tests #{success ? "PASS" : "FAIL"}"
heredoc = <<~TEXT
  Tests #{success ? "PASS" : "FAIL"}
TEXT
regexp = /Tests #{success ? "PASS" : "FAIL"}/

# good
string = "Tests #{success ? 'PASS' : 'FAIL'}"
symbol = :"Tests #{success ? 'PASS' : 'FAIL'}"
heredoc = <<~TEXT
  Tests #{success ? 'PASS' : 'FAIL'}
TEXT
regexp = /Tests #{success ? 'PASS' : 'FAIL'}/

Example: EnforcedStyle: double_quotes

# bad
string = "Tests #{success ? 'PASS' : 'FAIL'}"
symbol = :"Tests #{success ? 'PASS' : 'FAIL'}"
heredoc = <<~TEXT
  Tests #{success ? 'PASS' : 'FAIL'}
TEXT
regexp = /Tests #{success ? 'PASS' : 'FAIL'}/

# good
string = "Tests #{success ? "PASS" : "FAIL"}"
symbol = :"Tests #{success ? "PASS" : "FAIL"}"
heredoc = <<~TEXT
  Tests #{success ? "PASS" : "FAIL"}
TEXT
regexp = /Tests #{success ? "PASS" : "FAIL"}/

Checks if empty lines around the bodies of classes match the configuration.

Example: EnforcedStyle: noemptylines (default)

# good

class Foo
  def bar
    # ...
  end
end

Example: EnforcedStyle: empty_lines

# good

class Foo

  def bar
    # ...
  end

end

Example: EnforcedStyle: emptylinesexcept_namespace

# good

class Foo
  class Bar

    # ...

  end
end

Example: EnforcedStyle: emptylinesspecial

# good
class Foo

  def bar; end

end

Example: EnforcedStyle: beginning_only

# good

class Foo

  def bar
    # ...
  end
end

Example: EnforcedStyle: ending_only

# good

class Foo
  def bar
    # ...
  end

end

Checks for redundant safe navigation calls. Use cases where a constant, named in camel case for classes and modules is nil are rare, and an offense is not detected when the receiver is a constant. The detection also applies to literal receivers, except for nil.

For all receivers, the instance_of?, kind_of?, is_a?, eql?, respond_to?, and equal? methods are checked by default. These are customizable with AllowedMethods option.

The AllowedMethods option specifies nil-safe methods, in other words, it is a method that is allowed to skip safe navigation. Note that the AllowedMethod option is not an option that specifies methods for which to suppress (allow) this cop's check.

In the example below, the safe navigation operator (&.) is unnecessary because NilClass has methods like respond_to? and is_a?.

Safety:

This cop is unsafe, because autocorrection can change the return type of the expression. An offending expression that previously could return nil will be autocorrected to never return nil.

Example:

# bad
CamelCaseConst&.do_something

# bad
do_something if attrs&.respond_to?(:[])

# good
do_something if attrs.respond_to?(:[])

# bad
while node&.is_a?(BeginNode)
  node = node.parent
end

# good
CamelCaseConst.do_something

# good
while node.is_a?(BeginNode)
  node = node.parent
end

# good - without `&.` this will always return `true`
foo&.respond_to?(:to_a)

# bad - for `nil`s conversion methods return default values for the type
foo&.to_h || {}
foo&.to_h { |k, v| [k, v] } || {}
foo&.to_a || []
foo&.to_i || 0
foo&.to_f || 0.0
foo&.to_s || ''

# good
foo.to_h
foo.to_h { |k, v| [k, v] }
foo.to_a
foo.to_i
foo.to_f
foo.to_s

Example: AllowedMethods: [nilsafemethod]

# bad
do_something if attrs&.nil_safe_method(:[])

# good
do_something if attrs.nil_safe_method(:[])
do_something if attrs&.not_nil_safe_method(:[])

Checks for unused block arguments.

Example:

# bad
do_something do |used, unused|
  puts used
end

do_something do |bar|
  puts :foo
end

define_method(:foo) do |bar|
  puts :baz
end

# good
do_something do |used, _unused|
  puts used
end

do_something do
  puts :foo
end

define_method(:foo) do |_bar|
  puts :baz
end

Example: IgnoreEmptyBlocks: true (default)

# good
do_something { |unused| }

Example: IgnoreEmptyBlocks: false

# bad
do_something { |unused| }

Example: AllowUnusedKeywordArguments: false (default)

# bad
do_something do |unused: 42|
  foo
end

Example: AllowUnusedKeywordArguments: true

# good
do_something do |unused: 42|
  foo
end

Checks for usage of comparison operators (==, >, <) to test numbers as zero, positive, or negative. These can be replaced by their respective predicate methods. This cop can also be configured to do the reverse.

This cop can be customized allowed methods with AllowedMethods. By default, there are no methods to allowed.

This cop disregards #nonzero? as its value is truthy or falsey, but not true and false, and thus not always interchangeable with != 0.

This cop allows comparisons to global variables, since they are often populated with objects which can be compared with integers, but are not themselves Integer polymorphic.

Safety:

This cop is unsafe because it cannot be guaranteed that the receiver defines the predicates or can be compared to a number, which may lead to a false positive for non-standard classes.

Example: EnforcedStyle: predicate (default)

# bad
foo == 0
0 > foo
bar.baz > 0

# good
foo.zero?
foo.negative?
bar.baz.positive?

Example: EnforcedStyle: comparison

# bad
foo.zero?
foo.negative?
bar.baz.positive?

# good
foo == 0
0 > foo
bar.baz > 0

Example: AllowedMethods: [] (default) with EnforcedStyle: predicate

# bad
foo == 0
0 > foo
bar.baz > 0

Example: AllowedMethods: [==] with EnforcedStyle: predicate

# good
foo == 0

# bad
0 > foo
bar.baz > 0

Example: AllowedPatterns: [] (default) with EnforcedStyle: comparison

# bad
foo.zero?
foo.negative?
bar.baz.positive?

Example: AllowedPatterns: ['zero'] with EnforcedStyle: predicate

# good
# bad
foo.zero?

# bad
foo.negative?
bar.baz.positive?

Checks for usage of comparison operators (==, >, <) to test numbers as zero, positive, or negative. These can be replaced by their respective predicate methods. This cop can also be configured to do the reverse.

This cop can be customized allowed methods with AllowedMethods. By default, there are no methods to allowed.

This cop disregards #nonzero? as its value is truthy or falsey, but not true and false, and thus not always interchangeable with != 0.

This cop allows comparisons to global variables, since they are often populated with objects which can be compared with integers, but are not themselves Integer polymorphic.

Safety:

This cop is unsafe because it cannot be guaranteed that the receiver defines the predicates or can be compared to a number, which may lead to a false positive for non-standard classes.

Example: EnforcedStyle: predicate (default)

# bad
foo == 0
0 > foo
bar.baz > 0

# good
foo.zero?
foo.negative?
bar.baz.positive?

Example: EnforcedStyle: comparison

# bad
foo.zero?
foo.negative?
bar.baz.positive?

# good
foo == 0
0 > foo
bar.baz > 0

Example: AllowedMethods: [] (default) with EnforcedStyle: predicate

# bad
foo == 0
0 > foo
bar.baz > 0

Example: AllowedMethods: [==] with EnforcedStyle: predicate

# good
foo == 0

# bad
0 > foo
bar.baz > 0

Example: AllowedPatterns: [] (default) with EnforcedStyle: comparison

# bad
foo.zero?
foo.negative?
bar.baz.positive?

Example: AllowedPatterns: ['zero'] with EnforcedStyle: predicate

# good
# bad
foo.zero?

# bad
foo.negative?
bar.baz.positive?

Checks if uses of quotes match the configured preference.

Example: EnforcedStyle: single_quotes (default)

# bad
"No special symbols"
"No string interpolation"
"Just text"

# good
'No special symbols'
'No string interpolation'
'Just text'
"Wait! What's #{this}!"

Example: EnforcedStyle: double_quotes

# bad
'Just some text'
'No special chars or interpolation'

# good
"Just some text"
"No special chars or interpolation"
"Every string in #{project} uses double_quotes"

Checks for numeric comparisons that can be replaced by a predicate method, such as receiver.length == 0, receiver.length > 0, and receiver.length != 0, receiver.length < 1 and receiver.size == 0 that can be replaced by receiver.empty? and !receiver.empty?.

NOTE: File, Tempfile, and StringIO do not have empty? so allow size == 0 and size.zero?.

Safety:

This cop is unsafe because it cannot be guaranteed that the receiver has an empty? method that is defined in terms of length. If there is a non-standard class that redefines length or empty?, the cop may register a false positive.

Example:

# bad
[1, 2, 3].length == 0
0 == "foobar".length
array.length < 1
{a: 1, b: 2}.length != 0
string.length > 0
hash.size > 0

# good
[1, 2, 3].empty?
"foobar".empty?
array.empty?
!{a: 1, b: 2}.empty?
!string.empty?
!hash.empty?

Checks whether the end keywords of method definitions are aligned properly.

Two modes are supported through the EnforcedStyleAlignWith configuration parameter. If it's set to start_of_line (which is the default), the end shall be aligned with the start of the line where the def keyword is. If it's set to def, the end shall be aligned with the def keyword.

Example: EnforcedStyleAlignWith: startofline (default)

# bad

private def foo
            end

# good

private def foo
end

Example: EnforcedStyleAlignWith: def

# bad

private def foo
            end

# good

private def foo
        end

Checks for inconsistent indentation.

The difference between indented_internal_methods and normal is that the indented_internal_methods style prescribes that in classes and modules the protected and private modifier keywords shall be indented the same as public methods and that protected and private members shall be indented one step more than the modifiers. Other than that, both styles mean that entities on the same logical depth shall have the same indentation.

Example: EnforcedStyle: normal (default)

# bad
class A
  def test
    puts 'hello'
     puts 'world'
  end
end

# bad
class A
  def test
    puts 'hello'
    puts 'world'
  end

  protected

    def foo
    end

  private

    def bar
    end
end

# good
class A
  def test
    puts 'hello'
    puts 'world'
  end
end

# good
class A
  def test
    puts 'hello'
    puts 'world'
  end

  protected

  def foo
  end

  private

  def bar
  end
end

Example: EnforcedStyle: indentedinternalmethods

# bad
class A
  def test
    puts 'hello'
     puts 'world'
  end
end

# bad
class A
  def test
    puts 'hello'
    puts 'world'
  end

  protected

  def foo
  end

  private

  def bar
  end
end

# good
class A
  def test
    puts 'hello'
    puts 'world'
  end
end

# good
class A
  def test
    puts 'hello'
    puts 'world'
  end

  protected

    def foo
    end

  private

    def bar
    end
end

Checks for indentation that doesn't use the specified number of spaces.

See also the IndentationConsistency cop which is the companion to this one.

Example:

# bad
class A
 def test
  puts 'hello'
 end
end

# good
class A
  def test
    puts 'hello'
  end
end

Example: AllowedPatterns: ['^\s*module']

# bad
module A
class B
  def test
  puts 'hello'
  end
end
end

# good
module A
class B
  def test
    puts 'hello'
  end
end
end

Checks for uses of if with a negated condition. Only ifs without else are considered. There are three different styles:

• both
• prefix
• postfix

Example: EnforcedStyle: both (default)

# enforces `unless` for `prefix` and `postfix` conditionals

# bad

if !foo
  bar
end

# good

unless foo
  bar
end

# bad

bar if !foo

# good

bar unless foo

Example: EnforcedStyle: prefix

# enforces `unless` for just `prefix` conditionals

# bad

if !foo
  bar
end

# good

unless foo
  bar
end

# good

bar if !foo

Example: EnforcedStyle: postfix

# enforces `unless` for just `postfix` conditionals

# bad

bar if !foo

# good

bar unless foo

# good

if !foo
  bar
end

Transforms usages of a method call safeguarded by a non nil check for the variable whose method is being called to safe navigation (&.). If there is a method chain, all of the methods in the chain need to be checked for safety, and all of the methods will need to be changed to use safe navigation.

The default for ConvertCodeThatCanStartToReturnNil is false. When configured to true, this will check for code in the format !foo.nil? && foo.bar. As it is written, the return of this code is limited to false and whatever the return of the method is. If this is converted to safe navigation, foo&.bar can start returning nil as well as what the method returns.

The default for MaxChainLength is 2 We have limited the cop to not register an offense for method chains that exceed this option is set.

Safety:

Autocorrection is unsafe because if a value is false, the resulting code will have different behavior or raise an error.

x = false
x && x.foo  # return false
x&.foo      # raises NoMethodError

Example:

# bad
foo.bar if foo
foo.bar.baz if foo
foo.bar(param1, param2) if foo
foo.bar { |e| e.something } if foo
foo.bar(param) { |e| e.something } if foo

foo.bar if !foo.nil?
foo.bar unless !foo
foo.bar unless foo.nil?

foo && foo.bar
foo && foo.bar.baz
foo && foo.bar(param1, param2)
foo && foo.bar { |e| e.something }
foo && foo.bar(param) { |e| e.something }

foo ? foo.bar : nil
foo.nil? ? nil : foo.bar
!foo.nil? ? foo.bar : nil
!foo ? nil : foo.bar

# good
foo&.bar
foo&.bar&.baz
foo&.bar(param1, param2)
foo&.bar { |e| e.something }
foo&.bar(param) { |e| e.something }
foo && foo.bar.baz.qux # method chain with more than 2 methods
foo && foo.nil? # method that `nil` responds to

# Method calls that do not use `.`
foo && foo < bar
foo < bar if foo

# When checking `foo&.empty?` in a conditional, `foo` being `nil` will actually
# do the opposite of what the author intends.
foo && foo.empty?

# This could start returning `nil` as well as the return of the method
foo.nil? || foo.bar
!foo || foo.bar

# Methods that are used on assignment, arithmetic operation or
# comparison should not be converted to use safe navigation
foo.baz = bar if foo
foo.baz + bar if foo
foo.bar > 2 if foo

Enforces empty line after guard clause.

This cop allows # :nocov: directive after guard clause because SimpleCov excludes code from the coverage report by wrapping it in # :nocov::

def foo
  # :nocov:
  return if condition
  # :nocov:
  bar
end

Refer to SimpleCov's documentation for more details: https://github.com/simplecov-ruby/simplecov#ignoringskipping-code

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

Looks for trailing whitespace in the source code.

Example:

# The line in this example contains spaces after the 0.
# bad
x = 0

# The line in this example ends directly after the 0.
# good
x = 0

Example: AllowInHeredoc: false (default)

# The line in this example contains spaces after the 0.
# bad
code = <<~RUBY
  x = 0
RUBY

# ok
code = <<~RUBY
  x = 0 #{}
RUBY

# good
trailing_whitespace = ' '
code = <<~RUBY
  x = 0#{trailing_whitespace}
RUBY

Example: AllowInHeredoc: true

# The line in this example contains spaces after the 0.
# good
code = <<~RUBY
  x = 0
RUBY

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 permitted names that will never register an offense. The ForbiddenNames config option takes an array of restricted 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 `MinNameLength` 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

Checks if uses of quotes match the configured preference.

Example: EnforcedStyle: single_quotes (default)

# bad
"No special symbols"
"No string interpolation"
"Just text"

# good
'No special symbols'
'No string interpolation'
'Just text'
"Wait! What's #{this}!"

Example: EnforcedStyle: double_quotes

# bad
'Just some text'
'No special chars or interpolation'

# good
"Just some text"
"No special chars or interpolation"
"Every string in #{project} uses double_quotes"

Checks if uses of quotes match the configured preference.

Example: EnforcedStyle: single_quotes (default)

# bad
"No special symbols"
"No string interpolation"
"Just text"

# good
'No special symbols'
'No string interpolation'
'Just text'
"Wait! What's #{this}!"

Example: EnforcedStyle: double_quotes

# bad
'Just some text'
'No special chars or interpolation'

# good
"Just some text"
"No special chars or interpolation"
"Every string in #{project} uses double_quotes"

Checks the indentation of the first key in a hash literal where the opening brace and the first key are on separate lines. The other keys' indentations are handled by the HashAlignment cop.

By default, Hash literals that are arguments in a method call with parentheses, and where the opening curly brace of the hash is on the same line as the opening parenthesis of the method call, shall have their first key indented one step (two spaces) more than the position inside the opening parenthesis.

Other hash literals shall have their first key indented one step more than the start of the line where the opening curly brace is.

This default style is called 'specialinsideparentheses'. Alternative styles are 'consistent' and 'align_braces'. Here are examples:

Example: EnforcedStyle: specialinsideparentheses (default)

# The `special_inside_parentheses` style enforces that the first key
# in a hash literal where the opening brace and the first key are on
# separate lines is indented one step (two spaces) more than the
# position inside the opening parentheses.

# bad
hash = {
  key: :value
}
and_in_a_method_call({
  no: :difference
                     })
takes_multi_pairs_hash(x: {
  a: 1,
  b: 2
},
                       y: {
                         c: 1,
                         d: 2
                       })

# good
special_inside_parentheses
hash = {
  key: :value
}
but_in_a_method_call({
                       its_like: :this
                     })
takes_multi_pairs_hash(x: {
                         a: 1,
                         b: 2
                       },
                       y: {
                         c: 1,
                         d: 2
                       })

Example: EnforcedStyle: consistent

# The `consistent` style enforces that the first key in a hash
# literal where the opening brace and the first key are on
# separate lines is indented the same as a hash literal which is not
# defined inside a method call.

# bad
hash = {
  key: :value
}
but_in_a_method_call({
                       its_like: :this
                      })

# good
hash = {
  key: :value
}
and_in_a_method_call({
  no: :difference
})

Example: EnforcedStyle: align_braces

# The `align_brackets` style enforces that the opening and closing
# braces are indented to the same position.

# bad
and_now_for_something = {
                          completely: :different
}
takes_multi_pairs_hash(x: {
  a: 1,
  b: 2
},
                        y: {
                             c: 1,
                             d: 2
                           })

# good
and_now_for_something = {
                          completely: :different
                        }
takes_multi_pairs_hash(x: {
                            a: 1,
                            b: 2
                          },
                       y: {
                            c: 1,
                            d: 2
                          })

Checks for indentation that doesn't use the specified number of spaces.

See also the IndentationConsistency cop which is the companion to this one.

Example:

# bad
class A
 def test
  puts 'hello'
 end
end

# good
class A
  def test
    puts 'hello'
  end
end

Example: AllowedPatterns: ['^\s*module']

# bad
module A
class B
  def test
  puts 'hello'
  end
end
end

# good
module A
class B
  def test
    puts 'hello'
  end
end
end

Transforms usages of a method call safeguarded by a non nil check for the variable whose method is being called to safe navigation (&.). If there is a method chain, all of the methods in the chain need to be checked for safety, and all of the methods will need to be changed to use safe navigation.

The default for ConvertCodeThatCanStartToReturnNil is false. When configured to true, this will check for code in the format !foo.nil? && foo.bar. As it is written, the return of this code is limited to false and whatever the return of the method is. If this is converted to safe navigation, foo&.bar can start returning nil as well as what the method returns.

The default for MaxChainLength is 2 We have limited the cop to not register an offense for method chains that exceed this option is set.

Safety:

Autocorrection is unsafe because if a value is false, the resulting code will have different behavior or raise an error.

x = false
x && x.foo  # return false
x&.foo      # raises NoMethodError

Example:

# bad
foo.bar if foo
foo.bar.baz if foo
foo.bar(param1, param2) if foo
foo.bar { |e| e.something } if foo
foo.bar(param) { |e| e.something } if foo

foo.bar if !foo.nil?
foo.bar unless !foo
foo.bar unless foo.nil?

foo && foo.bar
foo && foo.bar.baz
foo && foo.bar(param1, param2)
foo && foo.bar { |e| e.something }
foo && foo.bar(param) { |e| e.something }

foo ? foo.bar : nil
foo.nil? ? nil : foo.bar
!foo.nil? ? foo.bar : nil
!foo ? nil : foo.bar

# good
foo&.bar
foo&.bar&.baz
foo&.bar(param1, param2)
foo&.bar { |e| e.something }
foo&.bar(param) { |e| e.something }
foo && foo.bar.baz.qux # method chain with more than 2 methods
foo && foo.nil? # method that `nil` responds to

# Method calls that do not use `.`
foo && foo < bar
foo < bar if foo

# When checking `foo&.empty?` in a conditional, `foo` being `nil` will actually
# do the opposite of what the author intends.
foo && foo.empty?

# This could start returning `nil` as well as the return of the method
foo.nil? || foo.bar
!foo || foo.bar

# Methods that are used on assignment, arithmetic operation or
# comparison should not be converted to use safe navigation
foo.baz = bar if foo
foo.baz + bar if foo
foo.bar > 2 if foo

Transforms usages of a method call safeguarded by a non nil check for the variable whose method is being called to safe navigation (&.). If there is a method chain, all of the methods in the chain need to be checked for safety, and all of the methods will need to be changed to use safe navigation.

The default for ConvertCodeThatCanStartToReturnNil is false. When configured to true, this will check for code in the format !foo.nil? && foo.bar. As it is written, the return of this code is limited to false and whatever the return of the method is. If this is converted to safe navigation, foo&.bar can start returning nil as well as what the method returns.

The default for MaxChainLength is 2 We have limited the cop to not register an offense for method chains that exceed this option is set.

Safety:

Autocorrection is unsafe because if a value is false, the resulting code will have different behavior or raise an error.

x = false
x && x.foo  # return false
x&.foo      # raises NoMethodError

Example:

# bad
foo.bar if foo
foo.bar.baz if foo
foo.bar(param1, param2) if foo
foo.bar { |e| e.something } if foo
foo.bar(param) { |e| e.something } if foo

foo.bar if !foo.nil?
foo.bar unless !foo
foo.bar unless foo.nil?

foo && foo.bar
foo && foo.bar.baz
foo && foo.bar(param1, param2)
foo && foo.bar { |e| e.something }
foo && foo.bar(param) { |e| e.something }

foo ? foo.bar : nil
foo.nil? ? nil : foo.bar
!foo.nil? ? foo.bar : nil
!foo ? nil : foo.bar

# good
foo&.bar
foo&.bar&.baz
foo&.bar(param1, param2)
foo&.bar { |e| e.something }
foo&.bar(param) { |e| e.something }
foo && foo.bar.baz.qux # method chain with more than 2 methods
foo && foo.nil? # method that `nil` responds to

# Method calls that do not use `.`
foo && foo < bar
foo < bar if foo

# When checking `foo&.empty?` in a conditional, `foo` being `nil` will actually
# do the opposite of what the author intends.
foo && foo.empty?

# This could start returning `nil` as well as the return of the method
foo.nil? || foo.bar
!foo || foo.bar

# Methods that are used on assignment, arithmetic operation or
# comparison should not be converted to use safe navigation
foo.baz = bar if foo
foo.baz + bar if foo
foo.bar > 2 if foo

Checks for indentation that doesn't use the specified number of spaces.

See also the IndentationConsistency cop which is the companion to this one.

Example:

# bad
class A
 def test
  puts 'hello'
 end
end

# good
class A
  def test
    puts 'hello'
  end
end

Example: AllowedPatterns: ['^\s*module']

# bad
module A
class B
  def test
  puts 'hello'
  end
end
end

# good
module A
class B
  def test
    puts 'hello'
  end
end
end

Looks for trailing blank lines and a final newline in the source code.

Example: EnforcedStyle: final_newline (default)

# `final_newline` looks for one newline at the end of files.

# bad
class Foo; end

# EOF

# bad
class Foo; end # EOF

# good
class Foo; end
# EOF

Example: EnforcedStyle: finalblankline

# `final_blank_line` looks for one blank line followed by a new line
# at the end of files.

# bad
class Foo; end
# EOF

# bad
class Foo; end # EOF

# good
class Foo; end

# EOF

Checks for redundant with_index.

Example:

# bad
ary.each_with_index do |v|
  v
end

# good
ary.each do |v|
  v
end

# bad
ary.each.with_index do |v|
  v
end

# good
ary.each do |v|
  v
end

Checks for grouping of accessors in class and module bodies. By default it enforces accessors to be placed in grouped declarations, but it can be configured to enforce separating them in multiple declarations.

NOTE: If there is a method call before the accessor method it is always allowed as it might be intended like Sorbet.

Example: EnforcedStyle: grouped (default)

# bad
class Foo
  attr_reader :bar
  attr_reader :bax
  attr_reader :baz
end

# good
class Foo
  attr_reader :bar, :bax, :baz
end

# good
class Foo
  # may be intended comment for bar.
  attr_reader :bar

  sig { returns(String) }
  attr_reader :bax

  may_be_intended_annotation :baz
  attr_reader :baz
end

Example: EnforcedStyle: separated

# bad
class Foo
  attr_reader :bar, :baz
end

# good
class Foo
  attr_reader :bar
  attr_reader :baz
end

Checks if uses of quotes match the configured preference.

Example: EnforcedStyle: single_quotes (default)

# bad
"No special symbols"
"No string interpolation"
"Just text"

# good
'No special symbols'
'No string interpolation'
'Just text'
"Wait! What's #{this}!"

Example: EnforcedStyle: double_quotes

# bad
'Just some text'
'No special chars or interpolation'

# good
"Just some text"
"No special chars or interpolation"
"Every string in #{project} uses double_quotes"

Checks that quotes inside string, symbol, and regexp interpolations match the configured preference.

Example: EnforcedStyle: single_quotes (default)

# bad
string = "Tests #{success ? "PASS" : "FAIL"}"
symbol = :"Tests #{success ? "PASS" : "FAIL"}"
heredoc = <<~TEXT
  Tests #{success ? "PASS" : "FAIL"}
TEXT
regexp = /Tests #{success ? "PASS" : "FAIL"}/

# good
string = "Tests #{success ? 'PASS' : 'FAIL'}"
symbol = :"Tests #{success ? 'PASS' : 'FAIL'}"
heredoc = <<~TEXT
  Tests #{success ? 'PASS' : 'FAIL'}
TEXT
regexp = /Tests #{success ? 'PASS' : 'FAIL'}/

Example: EnforcedStyle: double_quotes

# bad
string = "Tests #{success ? 'PASS' : 'FAIL'}"
symbol = :"Tests #{success ? 'PASS' : 'FAIL'}"
heredoc = <<~TEXT
  Tests #{success ? 'PASS' : 'FAIL'}
TEXT
regexp = /Tests #{success ? 'PASS' : 'FAIL'}/

# good
string = "Tests #{success ? "PASS" : "FAIL"}"
symbol = :"Tests #{success ? "PASS" : "FAIL"}"
heredoc = <<~TEXT
  Tests #{success ? "PASS" : "FAIL"}
TEXT
regexp = /Tests #{success ? "PASS" : "FAIL"}/

Checks for numeric comparisons that can be replaced by a predicate method, such as receiver.length == 0, receiver.length > 0, and receiver.length != 0, receiver.length < 1 and receiver.size == 0 that can be replaced by receiver.empty? and !receiver.empty?.

NOTE: File, Tempfile, and StringIO do not have empty? so allow size == 0 and size.zero?.

Safety:

This cop is unsafe because it cannot be guaranteed that the receiver has an empty? method that is defined in terms of length. If there is a non-standard class that redefines length or empty?, the cop may register a false positive.

Example:

# bad
[1, 2, 3].length == 0
0 == "foobar".length
array.length < 1
{a: 1, b: 2}.length != 0
string.length > 0
hash.size > 0

# good
[1, 2, 3].empty?
"foobar".empty?
array.empty?
!{a: 1, b: 2}.empty?
!string.empty?
!hash.empty?

Checks for numeric comparisons that can be replaced by a predicate method, such as receiver.length == 0, receiver.length > 0, and receiver.length != 0, receiver.length < 1 and receiver.size == 0 that can be replaced by receiver.empty? and !receiver.empty?.

NOTE: File, Tempfile, and StringIO do not have empty? so allow size == 0 and size.zero?.

Safety:

This cop is unsafe because it cannot be guaranteed that the receiver has an empty? method that is defined in terms of length. If there is a non-standard class that redefines length or empty?, the cop may register a false positive.

Example:

# bad
[1, 2, 3].length == 0
0 == "foobar".length
array.length < 1
{a: 1, b: 2}.length != 0
string.length > 0
hash.size > 0

# good
[1, 2, 3].empty?
"foobar".empty?
array.empty?
!{a: 1, b: 2}.empty?
!string.empty?
!hash.empty?

Checks whether the end keywords are aligned properly.

Three modes are supported through the EnforcedStyleAlignWith configuration parameter:

If it's set to keyword (which is the default), the end shall be aligned with the start of the keyword (if, class, etc.).

If it's set to variable the end shall be aligned with the left-hand-side of the variable assignment, if there is one.

If it's set to start_of_line, the end shall be aligned with the start of the line where the matching keyword appears.

This Layout/EndAlignment cop aligns with keywords (e.g. if, while, case) by default. On the other hand, Layout/BeginEndAlignment cop aligns with EnforcedStyleAlignWith: start_of_line by default due to ||= begin tends to align with the start of the line. Layout/DefEndAlignment cop also aligns with EnforcedStyleAlignWith: start_of_line by default. These style can be configured by each cop.

Example: EnforcedStyleAlignWith: keyword (default)

# bad

variable = if true
    end

# good

variable = if true
           end

variable =
  if true
  end

Example: EnforcedStyleAlignWith: variable

# bad

variable = if true
    end

# good

variable = if true
end

variable =
  if true
  end

Example: EnforcedStyleAlignWith: startofline

# bad

variable = if true
    end

puts(if true
     end)

# good

variable = if true
end

puts(if true
end)

variable =
  if true
  end

Checks for inconsistent indentation.

The difference between indented_internal_methods and normal is that the indented_internal_methods style prescribes that in classes and modules the protected and private modifier keywords shall be indented the same as public methods and that protected and private members shall be indented one step more than the modifiers. Other than that, both styles mean that entities on the same logical depth shall have the same indentation.

Example: EnforcedStyle: normal (default)

# bad
class A
  def test
    puts 'hello'
     puts 'world'
  end
end

# bad
class A
  def test
    puts 'hello'
    puts 'world'
  end

  protected

    def foo
    end

  private

    def bar
    end
end

# good
class A
  def test
    puts 'hello'
    puts 'world'
  end
end

# good
class A
  def test
    puts 'hello'
    puts 'world'
  end

  protected

  def foo
  end

  private

  def bar
  end
end

Example: EnforcedStyle: indentedinternalmethods

# bad
class A
  def test
    puts 'hello'
     puts 'world'
  end
end

# bad
class A
  def test
    puts 'hello'
    puts 'world'
  end

  protected

  def foo
  end

  private

  def bar
  end
end

# good
class A
  def test
    puts 'hello'
    puts 'world'
  end
end

# good
class A
  def test
    puts 'hello'
    puts 'world'
  end

  protected

    def foo
    end

  private

    def bar
    end
end

Checks that the indentation method is consistent. Either tabs only or spaces only are used for indentation.

Example: EnforcedStyle: spaces (default)

# bad
# This example uses a tab to indent bar.
def foo
  bar
end

# good
# This example uses spaces to indent bar.
def foo
  bar
end

Example: EnforcedStyle: tabs

# bad
# This example uses spaces to indent bar.
def foo
  bar
end

# good
# This example uses a tab to indent bar.
def foo
  bar
end

Checks that quotes inside string, symbol, and regexp interpolations match the configured preference.

Example: EnforcedStyle: single_quotes (default)

# bad
string = "Tests #{success ? "PASS" : "FAIL"}"
symbol = :"Tests #{success ? "PASS" : "FAIL"}"
heredoc = <<~TEXT
  Tests #{success ? "PASS" : "FAIL"}
TEXT
regexp = /Tests #{success ? "PASS" : "FAIL"}/

# good
string = "Tests #{success ? 'PASS' : 'FAIL'}"
symbol = :"Tests #{success ? 'PASS' : 'FAIL'}"
heredoc = <<~TEXT
  Tests #{success ? 'PASS' : 'FAIL'}
TEXT
regexp = /Tests #{success ? 'PASS' : 'FAIL'}/

Example: EnforcedStyle: double_quotes

# bad
string = "Tests #{success ? 'PASS' : 'FAIL'}"
symbol = :"Tests #{success ? 'PASS' : 'FAIL'}"
heredoc = <<~TEXT
  Tests #{success ? 'PASS' : 'FAIL'}
TEXT
regexp = /Tests #{success ? 'PASS' : 'FAIL'}/

# good
string = "Tests #{success ? "PASS" : "FAIL"}"
symbol = :"Tests #{success ? "PASS" : "FAIL"}"
heredoc = <<~TEXT
  Tests #{success ? "PASS" : "FAIL"}
TEXT
regexp = /Tests #{success ? "PASS" : "FAIL"}/

Checks that quotes inside string, symbol, and regexp interpolations match the configured preference.

Example: EnforcedStyle: single_quotes (default)

# bad
string = "Tests #{success ? "PASS" : "FAIL"}"
symbol = :"Tests #{success ? "PASS" : "FAIL"}"
heredoc = <<~TEXT
  Tests #{success ? "PASS" : "FAIL"}
TEXT
regexp = /Tests #{success ? "PASS" : "FAIL"}/

# good
string = "Tests #{success ? 'PASS' : 'FAIL'}"
symbol = :"Tests #{success ? 'PASS' : 'FAIL'}"
heredoc = <<~TEXT
  Tests #{success ? 'PASS' : 'FAIL'}
TEXT
regexp = /Tests #{success ? 'PASS' : 'FAIL'}/

Example: EnforcedStyle: double_quotes

# bad
string = "Tests #{success ? 'PASS' : 'FAIL'}"
symbol = :"Tests #{success ? 'PASS' : 'FAIL'}"
heredoc = <<~TEXT
  Tests #{success ? 'PASS' : 'FAIL'}
TEXT
regexp = /Tests #{success ? 'PASS' : 'FAIL'}/

# good
string = "Tests #{success ? "PASS" : "FAIL"}"
symbol = :"Tests #{success ? "PASS" : "FAIL"}"
heredoc = <<~TEXT
  Tests #{success ? "PASS" : "FAIL"}
TEXT
regexp = /Tests #{success ? "PASS" : "FAIL"}/

Checks for redundant begin blocks.

Currently it checks for code like this:

Example:

# bad
def redundant
  begin
    ala
    bala
  rescue StandardError => e
    something
  end
end

# good
def preferred
  ala
  bala
rescue StandardError => e
  something
end

# bad
begin
  do_something
end

# good
do_something

# bad
# When using Ruby 2.5 or later.
do_something do
  begin
    something
  rescue => ex
    anything
  end
end

# good
# In Ruby 2.5 or later, you can omit `begin` in `do-end` block.
do_something do
  something
rescue => ex
  anything
end

# good
# Stabby lambdas don't support implicit `begin` in `do-end` blocks.
-> do
  begin
    foo
  rescue Bar
    baz
  end
end

Checks for extra/unnecessary whitespace.

Example:

# good if AllowForAlignment is true
name      = "RuboCop"
# Some comment and an empty line

website  += "/rubocop/rubocop" unless cond
puts        "rubocop"          if     debug

# bad for any configuration
set_app("RuboCop")
website  = "https://github.com/rubocop/rubocop"

# good only if AllowBeforeTrailingComments is true
object.method(arg)  # this is a comment

# good even if AllowBeforeTrailingComments is false or not set
object.method(arg) # this is a comment

# good with either AllowBeforeTrailingComments or AllowForAlignment
object.method(arg)         # this is a comment
another_object.method(arg) # this is another comment
some_object.method(arg)    # this is some comment

Checks for missing top-level documentation of classes and modules. Classes with no body are exempt from the check and so are namespace modules - modules that have nothing in their bodies except classes, other modules, constant definitions or constant visibility declarations.

The documentation requirement is annulled if the class or module has a #:nodoc: comment next to it. Likewise, #:nodoc: all does the same for all its children.

Example:

# bad
class Person
  # ...
end

module Math
end

# good
# Description/Explanation of Person class
class Person
  # ...
end

# allowed
  # Class without body
  class Person
  end

  # Namespace - A namespace can be a class or a module
  # Containing a class
  module Namespace
    # Description/Explanation of Person class
    class Person
      # ...
    end
  end

  # Containing constant visibility declaration
  module Namespace
    class Private
    end

    private_constant :Private
  end

  # Containing constant definition
  module Namespace
    Public = Class.new
  end

  # Macro calls
  module Namespace
    extend Foo
  end

Example: AllowedConstants: ['ClassMethods']

# good
 module A
   module ClassMethods
     # ...
   end
  end

Helps you transition from mutable string literals to frozen string literals. It will add the # frozen_string_literal: true magic comment to the top of files to enable frozen string literals. Frozen string literals may be default in future Ruby. The comment will be added below a shebang and encoding comment. The frozen string literal comment is only valid in Ruby 2.3+.

Note that the cop will accept files where the comment exists but is set to false instead of true.

To require a blank line after this comment, please see Layout/EmptyLineAfterMagicComment cop.

Safety:

This cop's autocorrection is unsafe since any strings mutations will change from being accepted to raising FrozenError, as all strings will become frozen by default, and will need to be manually refactored.

Example: EnforcedStyle: always (default)

# The `always` style will always add the frozen string literal comment
# to a file, regardless of the Ruby version or if `freeze` or `<<` are
# called on a string literal.
# bad
module Bar
  # ...
end

# good
# frozen_string_literal: true

module Bar
  # ...
end

# good
# frozen_string_literal: false

module Bar
  # ...
end

Example: EnforcedStyle: never

# The `never` will enforce that the frozen string literal comment does
# not exist in a file.
# bad
# frozen_string_literal: true

module Baz
  # ...
end

# good
module Baz
  # ...
end

Example: EnforcedStyle: always_true

# The `always_true` style enforces that the frozen string literal
# comment is set to `true`. This is a stricter option than `always`
# and forces projects to use frozen string literals.
# bad
# frozen_string_literal: false

module Baz
  # ...
end

# bad
module Baz
  # ...
end

# good
# frozen_string_literal: true

module Bar
  # ...
end

Checks if uses of quotes match the configured preference.

Example: EnforcedStyle: single_quotes (default)

# bad
"No special symbols"
"No string interpolation"
"Just text"

# good
'No special symbols'
'No string interpolation'
'Just text'
"Wait! What's #{this}!"

Example: EnforcedStyle: double_quotes

# bad
'Just some text'
'No special chars or interpolation'

# good
"Just some text"
"No special chars or interpolation"
"Every string in #{project} uses double_quotes"

Checks for indentation that doesn't use the specified number of spaces.

See also the IndentationConsistency cop which is the companion to this one.

Example:

# bad
class A
 def test
  puts 'hello'
 end
end

# good
class A
  def test
    puts 'hello'
  end
end

Example: AllowedPatterns: ['^\s*module']

# bad
module A
class B
  def test
  puts 'hello'
  end
end
end

# good
module A
class B
  def test
    puts 'hello'
  end
end
end

Checks for the use of local variable names from an outer scope in block arguments or block-local variables. This mirrors the warning given by ruby -cw prior to Ruby 2.6: "shadowing outer local variable - foo".

NOTE: Shadowing of variables in block passed to Ractor.new is allowed because Ractor should not access outer variables. eg. following style is encouraged:

```ruby
worker_id, pipe = env
Ractor.new(worker_id, pipe) do |worker_id, pipe|
end
```

Example:

# bad

def some_method
  foo = 1

  2.times do |foo| # shadowing outer `foo`
    do_something(foo)
  end
end

Example:

# good

def some_method
  foo = 1

  2.times do |bar|
    do_something(bar)
  end
end

Checks for grouping of accessors in class and module bodies. By default it enforces accessors to be placed in grouped declarations, but it can be configured to enforce separating them in multiple declarations.

NOTE: If there is a method call before the accessor method it is always allowed as it might be intended like Sorbet.

Example: EnforcedStyle: grouped (default)

# bad
class Foo
  attr_reader :bar
  attr_reader :bax
  attr_reader :baz
end

# good
class Foo
  attr_reader :bar, :bax, :baz
end

# good
class Foo
  # may be intended comment for bar.
  attr_reader :bar

  sig { returns(String) }
  attr_reader :bax

  may_be_intended_annotation :baz
  attr_reader :baz
end

Example: EnforcedStyle: separated

# bad
class Foo
  attr_reader :bar, :baz
end

# good
class Foo
  attr_reader :bar
  attr_reader :baz
end

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.

From Ruby 3.0, this cop honours the magic comment 'shareableconstantvalue'. When this magic comment is set to any acceptable value other than none, it will suppress the offenses raised by this cop. It enforces frozen state.

NOTE: Regexp and Range literals are frozen objects since Ruby 3.0.

NOTE: From Ruby 3.0, interpolated strings are not frozen when # frozen-string-literal: true is used, so this cop enforces explicit freezing for such strings.

NOTE: From Ruby 3.0, this cop allows explicit freezing of constants when the shareable_constant_value directive is used.

Safety:

This cop's autocorrection is unsafe since any mutations on objects that are made frozen will change from being accepted to raising FrozenError, and will need to be manually refactored.

Example: EnforcedStyle: literals (default)

# bad
CONST = [1, 2, 3]

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

# good
CONST = <<~TESTING.freeze
  This is a heredoc
TESTING

# good
CONST = Something.new

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

Example:

# Magic comment - shareable_constant_value: literal

# bad
CONST = [1, 2, 3]

# good
# shareable_constant_value: literal
CONST = [1, 2, 3]

Checks for usage of comparison operators (==, >, <) to test numbers as zero, positive, or negative. These can be replaced by their respective predicate methods. This cop can also be configured to do the reverse.

This cop can be customized allowed methods with AllowedMethods. By default, there are no methods to allowed.

This cop disregards #nonzero? as its value is truthy or falsey, but not true and false, and thus not always interchangeable with != 0.

This cop allows comparisons to global variables, since they are often populated with objects which can be compared with integers, but are not themselves Integer polymorphic.

Safety:

This cop is unsafe because it cannot be guaranteed that the receiver defines the predicates or can be compared to a number, which may lead to a false positive for non-standard classes.

Example: EnforcedStyle: predicate (default)

# bad
foo == 0
0 > foo
bar.baz > 0

# good
foo.zero?
foo.negative?
bar.baz.positive?

Example: EnforcedStyle: comparison

# bad
foo.zero?
foo.negative?
bar.baz.positive?

# good
foo == 0
0 > foo
bar.baz > 0

Example: AllowedMethods: [] (default) with EnforcedStyle: predicate

# bad
foo == 0
0 > foo
bar.baz > 0

Example: AllowedMethods: [==] with EnforcedStyle: predicate

# good
foo == 0

# bad
0 > foo
bar.baz > 0

Example: AllowedPatterns: [] (default) with EnforcedStyle: comparison

# bad
foo.zero?
foo.negative?
bar.baz.positive?

Example: AllowedPatterns: ['zero'] with EnforcedStyle: predicate

# good
# bad
foo.zero?

# bad
foo.negative?
bar.baz.positive?

Checks that quotes inside string, symbol, and regexp interpolations match the configured preference.

Example: EnforcedStyle: single_quotes (default)

# bad
string = "Tests #{success ? "PASS" : "FAIL"}"
symbol = :"Tests #{success ? "PASS" : "FAIL"}"
heredoc = <<~TEXT
  Tests #{success ? "PASS" : "FAIL"}
TEXT
regexp = /Tests #{success ? "PASS" : "FAIL"}/

# good
string = "Tests #{success ? 'PASS' : 'FAIL'}"
symbol = :"Tests #{success ? 'PASS' : 'FAIL'}"
heredoc = <<~TEXT
  Tests #{success ? 'PASS' : 'FAIL'}
TEXT
regexp = /Tests #{success ? 'PASS' : 'FAIL'}/

Example: EnforcedStyle: double_quotes

# bad
string = "Tests #{success ? 'PASS' : 'FAIL'}"
symbol = :"Tests #{success ? 'PASS' : 'FAIL'}"
heredoc = <<~TEXT
  Tests #{success ? 'PASS' : 'FAIL'}
TEXT
regexp = /Tests #{success ? 'PASS' : 'FAIL'}/

# good
string = "Tests #{success ? "PASS" : "FAIL"}"
symbol = :"Tests #{success ? "PASS" : "FAIL"}"
heredoc = <<~TEXT
  Tests #{success ? "PASS" : "FAIL"}
TEXT
regexp = /Tests #{success ? "PASS" : "FAIL"}/

Checks for uses of do in multi-line while/until statements.

Example:

# bad
while x.any? do
  do_something(x.pop)
end

# good
while x.any?
  do_something(x.pop)
end

Example:

# bad
until x.empty? do
  do_something(x.pop)
end

# good
until x.empty?
  do_something(x.pop)
end