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

Inherits:
Base
  • Object
show all
Extended by:
AutoCorrector
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 collapse

MSG =
'Use `ENV.fetch(%<key>s)` or `ENV.fetch(%<key>s, nil)` instead of `ENV[%<key>s]`.'

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, 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, 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

#env_with_bracket?(node) ⇒ Object


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

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

#on_send(node) ⇒ Object


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# 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