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

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

Use a guard clause instead of wrapping the code inside a conditional expression

Example:

# bad
def test
  if something
    work
  end
end

# good
def test
  return unless something
  work
end

# also good
def test
  work if something
end

# bad
if something
  raise 'exception'
else
  ok
end

# good
raise 'exception' if something
ok

Use a guard clause instead of wrapping the code inside a conditional expression

Example:

# bad
def test
  if something
    work
  end
end

# good
def test
  return unless something
  work
end

# also good
def test
  work if something
end

# bad
if something
  raise 'exception'
else
  ok
end

# good
raise 'exception' if something
ok

This cops checks the indentation of the here document bodies. The bodies are indented one step. In Ruby 2.3 or newer, squiggly heredocs (<<~) should be used. If you use the older rubies, you should introduce some library to your project (e.g. ActiveSupport, Powerpack or Unindent). Note: When Metrics/LineLength's AllowHeredoc is false(not default), this cop does not add any offenses for long here documents to avoid Metrics/LineLength's offenses.

Example:

# bad
<<-RUBY
something
RUBY

# good
# When EnforcedStyle is squiggly, bad code is auto-corrected to the
# following code.
<<~RUBY
  something
RUBY

# good
# When EnforcedStyle is active_support, bad code is auto-corrected to
# the following code.
<<-RUBY.strip_heredoc
  something
RUBY

This cop checks for non-ascii (non-English) characters in comments. You could set an array of allowed non-ascii chars in AllowedChars attribute (empty by default).

Example:

# bad
# Translates from English to 日本語。

# good
# Translates from English to Japanese

This cop 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, or constant definitions.

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

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

This cop checks that your heredocs are using meaningful delimiters. By default it disallows END and EO*, and can be configured through blacklisting additional delimiters.

Example:

# good
<<-SQL
  SELECT * FROM foo
SQL

# bad
<<-END
  SELECT * FROM foo
END

# bad
<<-EOS
  SELECT * FROM foo
EOS

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

Example:

# bad
CONST = [1, 2, 3]

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

Use a guard clause instead of wrapping the code inside a conditional expression

Example:

# bad
def test
  if something
    work
  end
end

# good
def test
  return unless something
  work
end

# also good
def test
  work if something
end

# bad
if something
  raise 'exception'
else
  ok
end

# good
raise 'exception' if something
ok

This cop checks for non-ascii (non-English) characters in comments. You could set an array of allowed non-ascii chars in AllowedChars attribute (empty by default).

Example:

# bad
# Translates from English to 日本語。

# good
# Translates from English to Japanese

This cop checks for non-ascii (non-English) characters in comments. You could set an array of allowed non-ascii chars in AllowedChars attribute (empty by default).

Example:

# bad
# Translates from English to 日本語。

# good
# Translates from English to Japanese