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|
# frozen_string_literal: true
module RuboCop
module Cop
module RSpec
# Checks for explicitly referenced test subjects.
#
# RSpec lets you declare an "implicit subject" using `subject { ... }`
# which allows for tests like `it { is_expected.to be_valid }`.
# If you need to reference your test subject you should explicitly
# name it using `subject(:your_subject_name) { ... }`. Your test subjects
# should be the most important object in your tests so they deserve
# a descriptive name.
#
# This cop can be configured in your configuration using `EnforcedStyle`,
# and `IgnoreSharedExamples` which will not report offenses for implicit
# subjects in shared example groups.
#
# @example `EnforcedStyle: always` (default)
# # bad
# RSpec.describe User do
# subject { described_class.new }
#
# it 'is valid' do
# expect(subject.valid?).to be(true)
# end
# end
#
# # good
# RSpec.describe User do
# subject(:user) { described_class.new }
#
# it 'is valid' do
# expect(user.valid?).to be(true)
# end
# end
#
# # also good
# RSpec.describe User do
# subject(:user) { described_class.new }
#
# it { is_expected.to be_valid }
# end
#
# @example `EnforcedStyle: named_only`
# # bad
# RSpec.describe User do
# subject(:user) { described_class.new }
#
# it 'is valid' do
# expect(subject.valid?).to be(true)
# end
# end
#
# # good
# RSpec.describe User do
# subject(:user) { described_class.new }
#
# it 'is valid' do
# expect(user.valid?).to be(true)
# end
# end
#
# # also good
# RSpec.describe User do
# subject { described_class.new }
#
# it { is_expected.to be_valid }
# end
#
# # acceptable
# RSpec.describe User do
# subject { described_class.new }
#
# it 'is valid' do
# expect(subject.valid?).to be(true)
# end
# end
class NamedSubject < Base
include ConfigurableEnforcedStyle
MSG = 'Name your test subject if you need to reference it explicitly.'
# @!method example_or_hook_block?(node)
def_node_matcher :example_or_hook_block?,
block_pattern('{#Examples.all #Hooks.all}')
# @!method shared_example?(node)
def_node_matcher :shared_example?,
block_pattern('#SharedGroups.examples')
# @!method subject_usage(node)
def_node_search :subject_usage, '$(send nil? :subject)'
def on_block(node) # rubocop:disable InternalAffairs/NumblockHandler
if !example_or_hook_block?(node) || ignored_shared_example?(node)
return
end
subject_usage(node) do |subject_node|
check_explicit_subject(subject_node)
end
end
private
def ignored_shared_example?(node)
cop_config['IgnoreSharedExamples'] &&
node.each_ancestor(:block).any?(&method(:shared_example?))
end
def check_explicit_subject(node)
return if allow_explicit_subject?(node)
add_offense(node.loc.selector)
end
def allow_explicit_subject?(node)
!always? && !named_only?(node)
end
def always?
style == :always
end
def named_only?(node)
style == :named_only &&
subject_definition_is_named?(node)
end
def subject_definition_is_named?(node)
subject = nearest_subject(node)
subject&.send_node&.arguments?
end
def nearest_subject(node)
node
.each_ancestor(:block)
.lazy
.map { |block_node| find_subject(block_node) }
.find(&:itself)
end
def find_subject(block_node)
block_node.body.child_nodes.find { |send_node| subject?(send_node) }
end
end
end
end
end
|
