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Class: RuboCop::Cop::Style::ReturnNilInPredicateMethodDefinition

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, ::RuboCop::Cop::AutoCorrector, ::RuboCop::Cop::Base, ::RuboCop::ExcludeLimit, NodePattern::Macros, RuboCop::AST::Sexp
Instance Chain:
self, ::RuboCop::Cop::AllowedPattern, ::RuboCop::Cop::AllowedMethods, ::RuboCop::Cop::Base, ::RuboCop::Cop::AutocorrectLogic, ::RuboCop::Cop::IgnoredNode, ::RuboCop::Util, RuboCop::AST::Sexp
Inherits: RuboCop::Cop::Base
Defined in: lib/rubocop/cop/style/return_nil_in_predicate_method_definition.rb

Overview

Checks for predicate method definitions that return nil. A predicate method should only return a boolean value.

Examples:

# bad
def foo?
  return if condition

  do_something?
end

# bad
def foo?
  return nil if condition

  do_something?
end

# good
def foo?
  return false if condition

  do_something?
end

# bad
def foo?
  if condition
    nil
  else
    true
  end
end

# good
def foo?
  if condition
    false
  else
    true
  end
end

AllowedMethods: ['foo?']

# good
def foo?
  return if condition

  do_something?
end

AllowedPatterns: [/foo/]

# good
def foo?
  return if condition

  do_something?
end

Cop Safety Information:

  • Autocorrection is marked as unsafe because the change of the return value from nil to false could potentially lead to incompatibility issues.

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

Class Attribute Summary

::RuboCop::Cop::AutoCorrector - Extended

support_autocorrect?

::RuboCop::Cop::Base - Inherited

.gem_requirements, .lint?,
.support_autocorrect?

Returns if class supports autocorrect.
.support_multiple_source?

Override if your cop should be called repeatedly for multiple investigations Between calls to on_new_investigation and on_investigation_end, the result of processed_source will remain constant.

Class Method Summary

::RuboCop::Cop::Base - Inherited

.autocorrect_incompatible_with

List of cops that should not try to autocorrect at the same time as this cop.
.badge

Naming.
.callbacks_needed, .cop_name, .department,
.documentation_url

Returns a url to view this cops documentation online.
.exclude_from_registry

Call for abstract Cop classes.
.inherited,
.joining_forces

Override and return the Force class(es) you need to join.
.match?

Returns true if the cop name or the cop namespace matches any of the given names.
.new,
.requires_gem

Register a version requirement for the given gem name.
.restrict_on_send

::RuboCop::ExcludeLimit - Extended

exclude_limit

Sets up a configuration option to have an exclude limit tracked.
transform

Instance Attribute Summary

::RuboCop::Cop::AllowedPattern - Included

#ignored_line?, #matches_ignored_pattern?

::RuboCop::Cop::AllowedMethods - Included

#ignored_method?

::RuboCop::Cop::Base - Inherited

#active_support_extensions_enabled?, #always_autocorrect?, #config, #config_to_allow_offenses, #config_to_allow_offenses=, #contextual_autocorrect?, #processed_source, #string_literals_frozen_by_default?, #target_satisfies_all_gem_version_requirements?

::RuboCop::Cop::AutocorrectLogic - Included

#autocorrect?, #autocorrect_enabled?, #autocorrect_requested?, #autocorrect_with_disable_uncorrectable?, #correctable?, #disable_uncorrectable?, #safe_autocorrect?

Instance Method Summary

::RuboCop::Cop::AllowedPattern - Included

#allowed_line?, #allowed_patterns, #cop_config_deprecated_methods_values, #cop_config_patterns_values, #matches_allowed_pattern?

::RuboCop::Cop::AllowedMethods - Included

#allowed_method?, #allowed_methods, #cop_config_allowed_methods, #cop_config_deprecated_values

::RuboCop::Cop::Base - Inherited

#add_global_offense

Adds an offense that has no particular location.
#add_offense

Adds an offense on the specified range (or node with an expression) Unless that offense is disabled for this range, a corrector will be yielded to provide the cop the opportunity to autocorrect the offense.
#begin_investigation

Called before any investigation.
#callbacks_needed,
#cop_config

Configuration Helpers.
#cop_name, #excluded_file?,
#external_dependency_checksum

This method should be overridden when a cop’s behavior depends on state that lives outside of these locations:
#inspect,
#message

Gets called if no message is specified when calling add_offense or add_global_offense Cops are discouraged to override this; instead pass your message directly.
#name

Alias for Base#cop_name.
#offenses,
#on_investigation_end

Called after all on_…​
#on_new_investigation

Called before all on_…​
#on_other_file

Called instead of all on_…​
#parse

There should be very limited reasons for a Cop to do it’s own parsing.
#parser_engine,
#ready

Called between investigations.
#relevant_file?,
#target_gem_version

Returns a gems locked versions (i.e.
#target_rails_version, #target_ruby_version, #annotate, #apply_correction, #attempt_correction,
#callback_argument

Reserved for Cop::Cop.
#complete_investigation

Called to complete an investigation.
#correct, #current_corrector,
#current_offense_locations

Reserved for Commissioner:
#current_offenses, #currently_disabled_lines, #custom_severity, #default_severity, #disable_uncorrectable, #enabled_line?, #file_name_matches_any?, #find_message, #find_severity, #range_for_original, #range_from_node_or_range,
#reset_investigation

Actually private methods.
#use_corrector

::RuboCop::Cop::AutocorrectLogic - Included

#disable_offense, #disable_offense_at_end_of_line, #disable_offense_before_and_after, #disable_offense_with_eol_or_surround_comment, #heredoc_range, #max_line_length, #multiline_ranges, #multiline_string?,
#range_by_lines

Expand the given range to include all of any lines it covers.
#range_of_first_line, #range_overlaps_offense?, #string_continuation?, #surrounding_heredoc?, #surrounding_percent_array?

::RuboCop::Cop::IgnoredNode - Included

#ignore_node, #ignored_node?, #part_of_ignored_node?, #ignored_nodes

Constructor Details

This class inherits a constructor from RuboCop::Cop::Base

Instance Method Details

#handle_if(if_node) (private)

[ GitHub ] 

  


# File 'lib/rubocop/cop/style/return_nil_in_predicate_method_definition.rb', line 128



def handle_if(if_node)
  return unless if_node

  handle_implicit_return_values(if_node.if_branch)
  handle_implicit_return_values(if_node.else_branch)
end


  








  

    #handle_implicit_return_values(node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/return_nil_in_predicate_method_definition.rb', line 113



def handle_implicit_return_values(node)
  handle_if(last_node_of_type(node, :if))
  handle_nil(last_node_of_type(node, :nil))
end


  








  

    #handle_nil(nil_node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/return_nil_in_predicate_method_definition.rb', line 122



def handle_nil(nil_node)
  return unless nil_node

  register_offense(nil_node, 'false')
end


  








  

    #handle_return(return_node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/return_nil_in_predicate_method_definition.rb', line 118



def handle_return(return_node)
  register_offense(return_node, 'return false') if return_nil?(return_node)
end


  








  

    #last_node_of_type(node, type)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/return_nil_in_predicate_method_definition.rb', line 94



def last_node_of_type(node, type)
  return unless node
  return node if node_type?(node, type)
  return unless node.begin_type?
  return unless (last_child = node.children.last)

  last_child if last_child.is_a?(AST::Node) && node_type?(last_child, type)
end


  








  

    #node_type?(node, type)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/return_nil_in_predicate_method_definition.rb', line 103



def node_type?(node, type)
  node.type == type.to_sym
end


  








  

    #on_def(node)  
    Also known as: #on_defs
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/return_nil_in_predicate_method_definition.rb', line 81



def on_def(node)
  return unless node.predicate_method?
  return if allowed_method?(node.method_name) || matches_allowed_pattern?(node.method_name)
  return unless (body = node.body)

  body.each_descendant(:return) { |return_node| handle_return(return_node) }

  handle_implicit_return_values(body)
end


  








  

    #on_defs(node)  
  



  

    


Alias for #on_def.



  



  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/return_nil_in_predicate_method_definition.rb', line 90



alias on_defs on_def


  








  

    #register_offense(offense_node, replacement)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/return_nil_in_predicate_method_definition.rb', line 107



def register_offense(offense_node, replacement)
  add_offense(offense_node) do |corrector|
    corrector.replace(offense_node, replacement)
  end
end


  








  

    #return_nil?(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/style/return_nil_in_predicate_method_definition.rb', line 77



def_node_matcher :return_nil?, <<~PATTERN
  {(return) (return (nil))}
PATTERN