Class: RuboCop::Cop::Lint::RedundantSafeNavigation

Inherits:
Base
  • Object
show all
Extended by:
AutoCorrector
Includes:
AllowedMethods, RangeHelp
Defined in:
lib/rubocop/cop/lint/redundant_safe_navigation.rb

Overview

Checks for redundant safe navigation calls. Use cases where a constant, named in camel case for classes and modules is nil are rare, and an offense is not detected when the receiver is a snake case constant.

For all receivers, the instance_of?, kind_of?, is_a?, eql?, respond_to?, and equal? methods are checked by default. These are customizable with AllowedMethods option.

The AllowedMethods option specifies nil-safe methods, in other words, it is a method that is allowed to skip safe navigation. Note that the AllowedMethod option is not an option that specifies methods for which to suppress (allow) this cop’s check.

In the example below, the safe navigation operator (&.) is unnecessary because NilClass has methods like respond_to? and is_a?.

Examples:

# bad
CamelCaseConst&.do_something

# bad
do_something if attrs&.respond_to?(:[])

# good
do_something if attrs.respond_to?(:[])

# bad
while node&.is_a?(BeginNode)
  node = node.parent
end

# good
CamelCaseConst.do_something

# good
while node.is_a?(BeginNode)
  node = node.parent
end

# good - without `&.` this will always return `true`
foo&.respond_to?(:to_a)

AllowedMethods: [nil_safe_method]

# bad
do_something if attrs&.nil_safe_method(:[])

# good
do_something if attrs.nil_safe_method(:[])
do_something if attrs&.not_nil_safe_method(:[])

Cop Safety Information:

  • This cop is unsafe, because autocorrection can change the return type of the expression. An offending expression that previously could return nil will be autocorrected to never return nil.

Constant Summary collapse

MSG = 
'Redundant safe navigation detected.'
NIL_SPECIFIC_METHODS = 
(nil.methods - Object.new.methods).to_set.freeze
SNAKE_CASE = 
/\A[[:digit:][:upper:]_]+\z/.freeze

Constants inherited from Base

Base::RESTRICT_ON_SEND

Instance Attribute Summary

Attributes inherited from Base

#config, #processed_source

Instance Method Summary collapse

Methods included from AutoCorrector

support_autocorrect?

Methods inherited from Base

#active_support_extensions_enabled?, #add_global_offense, #add_offense, autocorrect_incompatible_with, badge, #begin_investigation, callbacks_needed, #callbacks_needed, #config_to_allow_offenses, #config_to_allow_offenses=, #cop_config, cop_name, #cop_name, department, documentation_url, exclude_from_registry, #excluded_file?, #external_dependency_checksum, inherited, #initialize, #inspect, joining_forces, lint?, match?, #message, #offenses, #on_investigation_end, #on_new_investigation, #on_other_file, #parse, #ready, #relevant_file?, support_autocorrect?, support_multiple_source?, #target_rails_version, #target_ruby_version

Methods included from ExcludeLimit

#exclude_limit

Methods included from AutocorrectLogic

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

Methods included from IgnoredNode

#ignore_node, #ignored_node?, #part_of_ignored_node?

Methods included from Util

silence_warnings

Constructor Details

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

Instance Method Details

#on_csend(node) ⇒ Object

rubocop:disable Metrics/AbcSize



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# File 'lib/rubocop/cop/lint/redundant_safe_navigation.rb', line 78

def on_csend(node)
  unless node.receiver.const_type? && !node.receiver.source.match?(SNAKE_CASE)
    return unless check?(node) && allowed_method?(node.method_name)
    return if respond_to_nil_specific_method?(node)
  end

  range = range_between(node.loc.dot.begin_pos, node.source_range.end_pos)
  add_offense(range) { |corrector| corrector.replace(node.loc.dot, '.') }
end

#respond_to_nil_specific_method?(node) ⇒ Object 



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# File 'lib/rubocop/cop/lint/redundant_safe_navigation.rb', line 73

def_node_matcher :respond_to_nil_specific_method?, <<~PATTERN
  (csend _ :respond_to? (sym %NIL_SPECIFIC_METHODS))
PATTERN