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Class: RuboCop::Cop::Lint::MissingSuper

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::ProjectIndexHelp, ::RuboCop::Cop::Base, ::RuboCop::Cop::AutocorrectLogic, ::RuboCop::Cop::IgnoredNode, ::RuboCop::Util, RuboCop::AST::Sexp
Inherits: RuboCop::Cop::Base
Defined in: lib/rubocop/cop/lint/missing_super.rb

Overview

Checks for the presence of constructors and lifecycle callbacks without calls to super.

This cop does not consider method_missing (and respond_to_missing?) because in some cases it makes sense to overtake what is considered a missing method. In other cases, the theoretical ideal handling could be challenging or verbose for no actual gain.

Autocorrection is not supported because the position of super cannot be determined automatically.

Object and BasicObject are allowed by this cop because of their stateless nature. However, sometimes you might want to allow other parent classes from this cop, for example in the case of an abstract class that is not meant to be called with super. In those cases, you can use the AllowedParentClasses option to specify which classes should be allowed in addition to Object and BasicObject.

When AllCops/UseProjectIndex is enabled and the rubydex gem is installed, the constructor check additionally consults the project-wide index: if the class' entire ancestry is resolvable and no ancestor defines initialize, no offense is registered, since super would only reach the no-op Object#initialize. Classes whose ancestry contains an unresolvable superclass or mixin (e.g. one defined in a gem) are still reported.

Examples:

# bad
class Employee < Person
  def initialize(name, salary)
    @salary = salary
  end
end

# good
class Employee < Person
  def initialize(name, salary)
    super(name)
    @salary = salary
  end
end

# bad
Employee = Class.new(Person) do
  def initialize(name, salary)
    @salary = salary
  end
end

# good
Employee = Class.new(Person) do
  def initialize(name, salary)
    super(name)
    @salary = salary
  end
end

# bad
class Parent
  def self.inherited(base)
    do_something
  end
end

# good
class Parent
  def self.inherited(base)
    super
    do_something
  end
end

# good
class ClassWithNoParent
  def initialize
    do_something
  end
end

AllowedParentClasses: [MyAbstractClass]

# good
class MyConcreteClass < MyAbstractClass
  def initialize
    do_something
  end
end

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

::RuboCop::Cop::ProjectIndexHelp - Included

BUILTIN_DOCUMENT_URI, FILE_URI_PREFIX, WINDOWS_DRIVE_PREFIX

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::Base - Inherited

#active_support_extensions_enabled?, #always_autocorrect?, #config, #config_to_allow_offenses, #config_to_allow_offenses=, #contextual_autocorrect?, #processed_source, #project_index, #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::ProjectIndexHelp - Included

#external_dependency_checksum, #compute_project_index_signature,
#definitions_in_other_files

Returns the definitions among definitions that live in a file other than the one being inspected, ordered by path and line.
#indexed_singleton_member

A namespace without any singleton method has no singleton-class declaration of its own, so the lookup starts from the first ancestor that has one; its find_member covers the rest of the chain.
#indexed_singleton_of

The declaration of `declaration’s singleton class, or nil when no singleton method is defined on it anywhere in the project.
#inherited_index_member?

Whether an ancestor of scope other than scope itself defines member_name.
#lexical_nesting_of

The lexical nesting the node’s constants resolve through, outermost first.
#prior_definition_in_other_file, #project_index_signature,
#resolve_constant_in_index

Resolves a constant node the way Ruby does: the first segment through the lexical nesting and every following segment inside the previous one.
#same_file?

::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, #matches_absolute_include_pattern?, #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 Method Details

#allowed_class?(node) ⇒ Boolean (private)

[ GitHub ] 

  


# File 'lib/rubocop/cop/lint/missing_super.rb', line 159



def allowed_class?(node)
  allowed_classes.include?(node.const_name)
end


  








  

    #allowed_classes   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/missing_super.rb', line 163



def allowed_classes
  @allowed_classes ||= STATELESS_CLASSES + cop_config.fetch('AllowedParentClasses', [])
end


  








  

    #callback_method_def?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/missing_super.rb', line 136



def callback_method_def?(node)
  return false unless CALLBACKS.include?(node.method_name)

  node.each_ancestor(:class, :sclass, :module).first
end


  








  

    #class_new_block(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/missing_super.rb', line 108



def_node_matcher :class_new_block, <<~RUBY
  (any_block
    (send
      (const {nil? cbase} :Class) :new $_) ...)
RUBY


  








  

    #contains_super?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/missing_super.rb', line 142



def contains_super?(node)
  node.each_descendant(:super, :zsuper).any?
end


  








  

    #index_verified_stateless_ancestry?(class_node)  ⇒ Boolean  (private)
  



  

    


With the project index, the offense is skipped when the class' whole ancestry
is resolvable and none of the inherited ancestors defines initialize —
super would only reach the no-op Object#initialize. An unresolvable
superclass or mixin anywhere in the chain (e.g. a class from a gem) means
the ancestry cannot be verified and the offense is kept.



  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/missing_super.rb', line 172



def index_verified_stateless_ancestry?(class_node)
  return false unless project_index

  declaration = resolve_constant_in_index(class_node.identifier)
  return false unless declaration.is_a?(Rubydex::Class)

  ancestors = declaration.ancestors.to_a
  inherited = ancestors.reject { |ancestor| ancestor.name == declaration.name }
  return false if inherited.any? { |ancestor| ancestor.member('initialize()') }

  ancestors.all? { |ancestor| resolved_ancestry_definitions?(ancestor) }
end


  








  

    #inside_class_with_stateful_parent?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/missing_super.rb', line 146



def inside_class_with_stateful_parent?(node)
  if (block_node = node.each_ancestor(:any_block).first)
    return false unless (super_class = class_new_block(block_node))

    !allowed_class?(super_class)
  elsif (class_node = node.each_ancestor(:class).first)
    class_node.parent_class && !allowed_class?(class_node.parent_class) &&
      !index_verified_stateless_ancestry?(class_node)
  else
    false
  end
end


  








  

    #mixin_references_resolved?(definition)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/missing_super.rb', line 197



def mixin_references_resolved?(definition)
  return true unless definition.respond_to?(:mixins)

  definition.mixins.none? do |mixin|
    # `extend` affects the singleton class and cannot introduce an
    # inherited `initialize`.
    next false if mixin.is_a?(Rubydex::Extend)

    mixin.constant_reference.is_a?(Rubydex::UnresolvedConstantReference)
  end
end


  








  

    #offender?(node)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/missing_super.rb', line 132



def offender?(node)
  (node.method?(:initialize) || callback_method_def?(node)) && !contains_super?(node)
end


  








  

    #on_def(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/missing_super.rb', line 114



def on_def(node)
  return unless offender?(node)

  if node.method?(:initialize) && inside_class_with_stateful_parent?(node)
    add_offense(node, message: CONSTRUCTOR_MSG)
  elsif callback_method_def?(node)
    add_offense(node, message: CALLBACK_MSG)
  end
end


  








  

    #on_defs(node)  
  

  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/missing_super.rb', line 124



def on_defs(node)
  return if !callback_method_def?(node) || contains_super?(node)

  add_offense(node, message: CALLBACK_MSG)
end


  








  

    #resolved_ancestry_definitions?(declaration)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/missing_super.rb', line 185



def resolved_ancestry_definitions?(declaration)
  declaration.definitions.all? do |definition|
    superclass_reference_resolved?(definition) && mixin_references_resolved?(definition)
  end
end


  








  

    #superclass_reference_resolved?(definition)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'lib/rubocop/cop/lint/missing_super.rb', line 191



def superclass_reference_resolved?(definition)
  return true unless definition.is_a?(Rubydex::ClassDefinition)

  !definition.superclass.is_a?(Rubydex::UnresolvedConstantReference)
end