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Class: RuboCop::Cop::Style::FetchEnvVar

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:
Inherits: RuboCop::Cop::Base
Defined in: lib/rubocop/cop/style/fetch_env_var.rb

Overview

Suggests ENV.fetch for the replacement of ENV[]. ENV[] silently fails and returns nil when the environment variable is unset, which may cause unexpected behaviors when the developer forgets to set it. On the other hand, ENV.fetch raises KeyError or returns the explicitly specified default value.

Examples:

# bad
ENV['X']
x = ENV['X']

# good
ENV.fetch('X')
x = ENV.fetch('X')

# also good
!ENV['X']
ENV['X'].some_method # (e.g. `.nil?`)

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

Class Attribute Summary

::RuboCop::Cop::AutoCorrector - Extended

::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 an 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

Instance Method Summary

::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_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

::RuboCop::Cop::IgnoredNode - Included

Constructor Details

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

Instance Method Details

#allowable_use?(node) ⇒ Boolean (private)

The following are allowed cases:

  • Used as a flag (e.g., if ENV['X'] or !ENV['X']) because it simply checks whether the variable is set.

  • Receiving a message with dot syntax, e.g. ENV['X'].nil?.

  • ENV['key'] assigned by logical AND/OR assignment.

  • ENV['key'] is the LHS of a ||.

[ GitHub ]

  
# File 'lib/rubocop/cop/style/fetch_env_var.rb', line 105

def allowable_use?(node)
  used_as_flag?(node) || message_chained_with_dot?(node) || assigned?(node) || or_lhs?(node)
end

#allowed_var?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/fetch_env_var.rb', line 48

def allowed_var?(node)
  env_key_node = node.children.last
  env_key_node.str_type? && cop_config['AllowedVars'].include?(env_key_node.value)
end

#assigned?(node) ⇒ Boolean (private)

The following are allowed cases:

  • ENV['key'] is a receiver of ||=, e.g. ENV['X'] ||= y.

  • ENV['key'] is a receiver of &&=, e.g. ENV['X'] &&= y.

[ GitHub ]

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

def assigned?(node)
  return false unless (parent = node.parent)&.assignment?

  lhs, _method, _rhs = *parent
  node == lhs
end

#env_with_bracket?(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/fetch_env_var.rb', line 31

def_node_matcher :env_with_bracket?, <<~PATTERN
  (send (const nil? :ENV) :[] $_)
PATTERN

#message_chained_with_dot?(node) ⇒ Boolean (private)

Check if the node is a receiver and receives a message with dot syntax.

[ GitHub ]

  
# File 'lib/rubocop/cop/style/fetch_env_var.rb', line 89

def message_chained_with_dot?(node)
  return false if node.root?

  parent = node.parent
  return false if !parent.call_type? || parent.children.first != node

  parent.dot? || parent.safe_navigation?
end

#new_code(name_node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/fetch_env_var.rb', line 126

def new_code(name_node)
  "ENV.fetch(#{name_node.source}, nil)"
end

#offensive?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/fetch_env_var.rb', line 84

def offensive?(node)
  !(allowed_var?(node) || allowable_use?(node))
end

#on_send(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/fetch_env_var.rb', line 35

def on_send(node)
  env_with_bracket?(node) do |name_node|
    break unless offensive?(node)

    message = format(MSG, key: name_node.source)
    add_offense(node, message: message) do |corrector|
      corrector.replace(node, new_code(name_node))
    end
  end
end

#or_lhs?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/fetch_env_var.rb', line 120

def or_lhs?(node)
  return false unless (parent = node.parent)&.or_type?

  parent.lhs == node || parent.parent&.or_type?
end

#partial_matched?(node, condition) ⇒ Boolean (private)

Avoid offending in the following cases: ENV['key'] if ENV['key'] = x

[ GitHub ]

  
# File 'lib/rubocop/cop/style/fetch_env_var.rb', line 80

def partial_matched?(node, condition)
  node.child_nodes == node.child_nodes & condition.child_nodes
end

#used_as_flag?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/fetch_env_var.rb', line 53

def used_as_flag?(node)
  return false if node.root?
  return true if used_if_condition_in_body(node)

  node.parent.send_type? && (node.parent.prefix_bang? || node.parent.comparison_method?)
end

#used_if_condition_in_body(node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/fetch_env_var.rb', line 60

def used_if_condition_in_body(node)
  if_node = node.ancestors.find(&:if_type?)

  return false unless (condition = if_node&.condition)
  return true if condition.send_type? && (condition.child_nodes == node.child_nodes)

  used_in_condition?(node, condition)
end

#used_in_condition?(node, condition) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/style/fetch_env_var.rb', line 69

def used_in_condition?(node, condition)
  if condition.send_type?
    return true if condition.assignment_method? && partial_matched?(node, condition)
    return false if !condition.comparison_method? && !condition.predicate_method?
  end

  condition.child_nodes.any?(node)
end