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# frozen_string_literal: true
module RuboCop
module Cop
module RSpec
# Checks for instance variable usage in specs.
#
# This cop can be configured with the option `AssignmentOnly` which
# will configure the cop to only register offenses on instance
# variable usage if the instance variable is also assigned within
# the spec
#
# @example
# # bad
# describe MyClass do
# before { @foo = [] }
# it { expect(@foo).to be_empty }
# end
#
# # good
# describe MyClass do
# let(:foo) { [] }
# it { expect(foo).to be_empty }
# end
#
# @example with AssignmentOnly configuration
# # rubocop.yml
# # RSpec/InstanceVariable:
# # AssignmentOnly: false
#
# # bad
# describe MyClass do
# before { @foo = [] }
# it { expect(@foo).to be_empty }
# end
#
# # allowed
# describe MyClass do
# it { expect(@foo).to be_empty }
# end
#
# # good
# describe MyClass do
# let(:foo) { [] }
# it { expect(foo).to be_empty }
# end
#
class InstanceVariable < Base
include TopLevelGroup
MSG = 'Avoid instance variables – use let, ' \
'a method call, or a local variable (if possible).'
# @!method dynamic_class?(node)
def_node_matcher :dynamic_class?, <<-PATTERN
(block (send (const nil? :Class) :new ...) ...)
PATTERN
# @!method custom_matcher?(node)
def_node_matcher :custom_matcher?, <<-PATTERN
(block {
(send nil? :matcher sym)
(send (const (const nil? :RSpec) :Matchers) :define sym)
} ...)
PATTERN
# @!method ivar_usage(node)
def_node_search :ivar_usage, '$(ivar $_)'
# @!method ivar_assigned?(node)
def_node_search :ivar_assigned?, '(ivasgn % ...)'
def on_top_level_group(node)
ivar_usage(node) do |ivar, name|
next if valid_usage?(ivar)
next if assignment_only? && !ivar_assigned?(node, name)
add_offense(ivar)
end
end
private
def valid_usage?(node)
node.each_ancestor(:block).any? do |block|
dynamic_class?(block) || custom_matcher?(block)
end
end
def assignment_only?
cop_config['AssignmentOnly']
end
end
end
end
end
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