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 for a newline after the final magic comment.

Example:

# good
# frozen_string_literal: true
 
# Some documentation for Person
class Person
  # Some code
end
 
# bad
# frozen_string_literal: true
# Some documentation for Person
class Person
  # Some code
end

Checks for a newline after the final magic comment.

Example:

# good
# frozen_string_literal: true
 
# Some documentation for Person
class Person
  # Some code
end
 
# bad
# frozen_string_literal: true
# Some documentation for Person
class Person
  # Some code
end

Dependencies in the gemspec should be alphabetically sorted.

Example:

# bad
spec.add_dependency 'rubocop'
spec.add_dependency 'rspec'
 
# good
spec.add_dependency 'rspec'
spec.add_dependency 'rubocop'
 
# good
spec.add_dependency 'rubocop'
 
spec.add_dependency 'rspec'
 
# bad
spec.add_development_dependency 'rubocop'
spec.add_development_dependency 'rspec'
 
# good
spec.add_development_dependency 'rspec'
spec.add_development_dependency 'rubocop'
 
# good
spec.add_development_dependency 'rubocop'
 
spec.add_development_dependency 'rspec'
 
# bad
spec.add_runtime_dependency 'rubocop'
spec.add_runtime_dependency 'rspec'
 
# good
spec.add_runtime_dependency 'rspec'
spec.add_runtime_dependency 'rubocop'
 
# good
spec.add_runtime_dependency 'rubocop'
 
spec.add_runtime_dependency 'rspec'
 
# good only if TreatCommentsAsGroupSeparators is true
# For code quality
spec.add_dependency 'rubocop'
# For tests
spec.add_dependency 'rspec'

Checks for a newline after the final magic comment.

Example:

# good
# frozen_string_literal: true
 
# Some documentation for Person
class Person
  # Some code
end
 
# bad
# frozen_string_literal: true
# Some documentation for Person
class Person
  # Some code
end

Checks for a newline after the final magic comment.

Example:

# good
# frozen_string_literal: true
 
# Some documentation for Person
class Person
  # Some code
end
 
# bad
# frozen_string_literal: true
# Some documentation for Person
class Person
  # Some code
end

Checks for a newline after the final magic comment.

Example:

# good
# frozen_string_literal: true
 
# Some documentation for Person
class Person
  # Some code
end
 
# bad
# frozen_string_literal: true
# Some documentation for Person
class Person
  # Some code
end

Checks for a newline after the final magic comment.

Example:

# good
# frozen_string_literal: true
 
# Some documentation for Person
class Person
  # Some code
end
 
# bad
# frozen_string_literal: true
# Some documentation for Person
class Person
  # Some code
end

This cop checks whether method definitions are separated by one empty line.

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

AllowAdjacentOneLineDefs can be used to configure is adjacent one line methods definitions are an offense

Example:

# bad
def a
end
def b
end

Example:

# good
def a
end
 
def b
end

Dependencies in the gemspec should be alphabetically sorted.

Example:

# bad
spec.add_dependency 'rubocop'
spec.add_dependency 'rspec'
 
# good
spec.add_dependency 'rspec'
spec.add_dependency 'rubocop'
 
# good
spec.add_dependency 'rubocop'
 
spec.add_dependency 'rspec'
 
# bad
spec.add_development_dependency 'rubocop'
spec.add_development_dependency 'rspec'
 
# good
spec.add_development_dependency 'rspec'
spec.add_development_dependency 'rubocop'
 
# good
spec.add_development_dependency 'rubocop'
 
spec.add_development_dependency 'rspec'
 
# bad
spec.add_runtime_dependency 'rubocop'
spec.add_runtime_dependency 'rspec'
 
# good
spec.add_runtime_dependency 'rspec'
spec.add_runtime_dependency 'rubocop'
 
# good
spec.add_runtime_dependency 'rubocop'
 
spec.add_runtime_dependency 'rspec'
 
# good only if TreatCommentsAsGroupSeparators is true
# For code quality
spec.add_dependency 'rubocop'
# For tests
spec.add_dependency 'rspec'

Checks for unnecessary require statement.

The following features are unnecessary require statement because they are already loaded.

ruby -ve 'p $LOADED_FEATURES.reject { |feature| %r|/| =~ feature }' ruby 2.2.8p477 (2017-09-14 revision 59906) [x86_64-darwin13] ["enumerator.so", "rational.so", "complex.so", "thread.rb"]

This cop targets Ruby 2.2 or higher containing these 4 features.

Example:

# bad
require 'unloaded_feature'
require 'thread'
 
# good
require 'unloaded_feature'

Checks for a newline after the final magic comment.

Example:

# good
# frozen_string_literal: true
 
# Some documentation for Person
class Person
  # Some code
end
 
# bad
# frozen_string_literal: true
# Some documentation for Person
class Person
  # Some code
end

Checks for a newline after the final magic comment.

Example:

# good
# frozen_string_literal: true
 
# Some documentation for Person
class Person
  # Some code
end
 
# bad
# frozen_string_literal: true
# Some documentation for Person
class Person
  # Some code
end

Dependencies in the gemspec should be alphabetically sorted.

Example:

# bad
spec.add_dependency 'rubocop'
spec.add_dependency 'rspec'
 
# good
spec.add_dependency 'rspec'
spec.add_dependency 'rubocop'
 
# good
spec.add_dependency 'rubocop'
 
spec.add_dependency 'rspec'
 
# bad
spec.add_development_dependency 'rubocop'
spec.add_development_dependency 'rspec'
 
# good
spec.add_development_dependency 'rspec'
spec.add_development_dependency 'rubocop'
 
# good
spec.add_development_dependency 'rubocop'
 
spec.add_development_dependency 'rspec'
 
# bad
spec.add_runtime_dependency 'rubocop'
spec.add_runtime_dependency 'rspec'
 
# good
spec.add_runtime_dependency 'rspec'
spec.add_runtime_dependency 'rubocop'
 
# good
spec.add_runtime_dependency 'rubocop'
 
spec.add_runtime_dependency 'rspec'
 
# good only if TreatCommentsAsGroupSeparators is true
# For code quality
spec.add_dependency 'rubocop'
# For tests
spec.add_dependency 'rspec'

This cops checks for two or more consecutive blank lines.

Example:

# bad - It has two empty lines.
some_method
# one empty line
# two empty lines
some_method
 
# good
some_method
# one empty line
some_method

Checks for a newline after the final magic comment.

Example:

# good
# frozen_string_literal: true
 
# Some documentation for Person
class Person
  # Some code
end
 
# bad
# frozen_string_literal: true
# Some documentation for Person
class Person
  # Some code
end

Checks for a newline after the final magic comment.

Example:

# good
# frozen_string_literal: true
 
# Some documentation for Person
class Person
  # Some code
end
 
# bad
# frozen_string_literal: true
# Some documentation for Person
class Person
  # Some code
end

Checks for a newline after the final magic comment.

Example:

# good
# frozen_string_literal: true
 
# Some documentation for Person
class Person
  # Some code
end
 
# bad
# frozen_string_literal: true
# Some documentation for Person
class Person
  # Some code
end