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Class: RuboCop::Cop::Naming::PredicatePrefix

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, ::RuboCop::Cop::Base, ::RuboCop::ExcludeLimit, NodePattern::Macros, RuboCop::AST::Sexp
Instance Chain:
self, ::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/naming/predicate_prefix.rb

Overview

Checks that predicate method names end with a question mark and do not start with a forbidden prefix.

A method is determined to be a predicate method if its name starts with one of the prefixes listed in the NamePrefix configuration. The list defaults to is_, has_, and have_ but may be overridden.

Predicate methods must end with a question mark.

When ForbiddenPrefixes is also set (as it is by default), predicate methods which begin with a forbidden prefix are not allowed, even if they end with a ?. These methods should be changed to remove the prefix.

When UseSorbetSigs set to true (optional), the cop will only report offenses if the method has a Sorbet sig with a return type of T::Boolean. Dynamic methods are not supported with this configuration.

Examples:

NamePrefix: ['is_', 'has_', 'have_'] (default)

# bad
def is_even(value)
end

# When ForbiddenPrefixes: ['is_', 'has_', 'have_'] (default)
# good
def even?(value)
end

# When ForbiddenPrefixes: []
# good
def is_even?(value)
end

NamePrefix: ['seems_to_be_']

# bad
def seems_to_be_even(value)
end

# When ForbiddenPrefixes: ['seems_to_be_']
# good
def even?(value)
end

# When ForbiddenPrefixes: []
# good
def seems_to_be_even?(value)
end

AllowedMethods: ['is_a?'] (default)

# Despite starting with the {is_} prefix, this method is allowed
# good
def is_a?(value)
end

AllowedMethods: ['is_even?']

# good
def is_even?(value)
end

UseSorbetSigs: false (default)

# bad
sig { returns(String) }
def is_this_thing_on
  "yes"
end

# good - Sorbet signature is not evaluated
sig { returns(String) }
def is_this_thing_on?
  "yes"
end

UseSorbetSigs: true

# bad
sig { returns(T::Boolean) }
def odd(value)
end

# good
sig { returns(T::Boolean) }
def odd?(value)
end

MethodDefinitionMacros: ['define_method', 'define_singleton_method'] (default)

# bad
define_method(:is_even) { |value| }

# good
define_method(:even?) { |value| }

MethodDefinitionMacros: ['def_node_matcher']

# bad
def_node_matcher(:is_even) { |value| }

# good
def_node_matcher(:even?) { |value| }

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

Class Attribute Summary

::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::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::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, #eol_comment, #eol_comment_would_be_inside_literal?, #heredoc_range, #line_with_eol_comment_too_long?, #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, #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 Attribute Details

#use_sorbet_sigs? ⇒ Boolean (readonly, private)

[ GitHub ] 

  


# File 'lib/rubocop/cop/naming/predicate_prefix.rb', line 194



def use_sorbet_sigs?
  cop_config['UseSorbetSigs']
end


  







Instance Method Details



  

    #allowed_method_name?(method_name, prefix)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/naming/predicate_prefix.rb', line 164



def allowed_method_name?(method_name, prefix)
  !(method_name.start_with?(prefix) && # cheap check to avoid allocating Regexp
      method_name.match?(/^#{prefix}[^0-9]/)) ||
    method_name == expected_name(method_name, prefix) ||
    method_name.end_with?('=') ||
    allowed_method?(method_name)
end


  








  

    #dynamic_method_define(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/naming/predicate_prefix.rb', line 107



def_node_matcher :dynamic_method_define, <<~PATTERN
  (send nil? #method_definition_macro?
    (sym $_)
    ...)
PATTERN


  








  

    #expected_name(method_name, prefix)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/naming/predicate_prefix.rb', line 172



def expected_name(method_name, prefix)
  new_name = if forbidden_prefixes.include?(prefix)
               method_name.sub(prefix, '')
             else
               method_name.dup
             end
  new_name << '?' unless method_name.end_with?('?')
  new_name
end


  








  

    #forbidden_prefixes   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/naming/predicate_prefix.rb', line 186



def forbidden_prefixes
  cop_config['ForbiddenPrefixes']
end


  








  

    #message(method_name, new_name)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/naming/predicate_prefix.rb', line 182



def message(method_name, new_name)
  "Rename `#{method_name}` to `#{new_name}`."
end


  








  

    #method_definition_macro?(macro_name)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/naming/predicate_prefix.rb', line 198



def method_definition_macro?(macro_name)
  cop_config['MethodDefinitionMacros'].include?(macro_name.to_s)
end


  








  

    #on_def(node)  
    Also known as: #on_defs
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/naming/predicate_prefix.rb', line 126



def on_def(node)
  predicate_prefixes.each do |prefix|
    method_name = node.method_name.to_s

    next if allowed_method_name?(method_name, prefix)
    next if use_sorbet_sigs? && !sorbet_sig?(node, return_type: 'T::Boolean')

    add_offense(
      node.loc.name,
      message: message(method_name, expected_name(method_name, prefix))
    )
  end
end


  








  

    #on_defs(node)  
  



  

    


Alias for #on_def.



  



  [ GitHub ]


  

  


# File 'lib/rubocop/cop/naming/predicate_prefix.rb', line 139



alias on_defs on_def


  








  

    #on_send(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/naming/predicate_prefix.rb', line 113



def on_send(node)
  dynamic_method_define(node) do |method_name|
    predicate_prefixes.each do |prefix|
      next if allowed_method_name?(method_name.to_s, prefix)

      add_offense(
        node.first_argument,
        message: message(method_name, expected_name(method_name.to_s, prefix))
      )
    end
  end
end


  








  

    #predicate_prefixes   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/naming/predicate_prefix.rb', line 190



def predicate_prefixes
  cop_config['NamePrefix']
end


  








  

    #sorbet_return_type(node)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/naming/predicate_prefix.rb', line 154



def_node_matcher :sorbet_return_type, <<~PATTERN
  (block (send nil? :sig) args (send _ :returns $_type))
PATTERN


  








  

    #sorbet_sig?(node, return_type: nil)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/naming/predicate_prefix.rb', line 158



def sorbet_sig?(node, return_type: nil)
  return false unless (type = sorbet_return_type(node.left_sibling))

  type.source == return_type
end


  








  

    #validate_config  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/naming/predicate_prefix.rb', line 141



def validate_config
  forbidden_prefixes.each do |forbidden_prefix|
    next if predicate_prefixes.include?(forbidden_prefix)

    raise ValidationError, <<~MSG.chomp
      The `Naming/PredicatePrefix` cop is misconfigured. Prefix #{forbidden_prefix} must be included in NamePrefix because it is included in ForbiddenPrefixes.
    MSG
  end
end