class RuboCop::Cop::RSpec::DescribedClass
Checks that tests use `described_class`.
If the first argument of describe is a class, the class is exposed to each example via described_class.
This cop can be configured using the `EnforcedStyle` and `SkipBlocks` options.
@example `EnforcedStyle: described_class`
# bad describe MyClass do subject { MyClass.do_something } end # good describe MyClass do subject { described_class.do_something } end
@example `EnforcedStyle: explicit`
# bad describe MyClass do subject { described_class.do_something } end # good describe MyClass do subject { MyClass.do_something } end
There's a known caveat with rspec-rails's `controller` helper that runs its block in a different context, and `described_class` is not available to it. `SkipBlocks` option excludes detection in all non-RSpec related blocks.
To narrow down this setting to only a specific directory, it is possible to use an overriding configuration file local to that directory.
@example `SkipBlocks: true`
# spec/controllers/.rubocop.yml # RSpec/DescribedClass: # SkipBlocks: true # acceptable describe MyConcern do controller(ApplicationController) do include MyConcern end end
Constants
- DESCRIBED_CLASS
- MSG
Public Instance Methods
# File lib/rubocop/cop/rspec/described_class.rb, line 85 def on_block(node) # In case the explicit style is used, we need to remember what's # being described. @described_class, body = described_constant(node) return unless body find_usage(body) do |match| msg = message(match.const_name) add_offense(match, message: msg) do |corrector| autocorrect(corrector, match) end end end
Private Instance Methods
# File lib/rubocop/cop/rspec/described_class.rb, line 102 def autocorrect(corrector, match) replacement = if style == :described_class DESCRIBED_CLASS else @described_class.const_name end corrector.replace(match, replacement) end
@param namespace [Array<Symbol>] @param const [Array<Symbol>] @return [Array<Symbol>] @example
# nil represents base constant collapse_namespace([], :C) # => [:C] collapse_namespace([:A, :B], [:C) # => [:A, :B, :C] collapse_namespace([:A, :B], [:B, :C) # => [:A, :B, :C] collapse_namespace([:A, :B], [nil, :C) # => [nil, :C] collapse_namespace([:A, :B], [nil, :B, :C) # => [nil, :B, :C]
# File lib/rubocop/cop/rspec/described_class.rb, line 180 def collapse_namespace(namespace, const) return const if namespace.empty? return const if const.first.nil? start = [0, (namespace.length - const.length)].max max = namespace.length intersection = (start..max).find do |shift| namespace[shift, max - shift] == const[0, max - shift] end [*namespace[0, intersection], *const] end
@param node [RuboCop::AST::Node] @return [Array<Symbol>] @example
const_name(s(:const, nil, :C)) # => [:C] const_name(s(:const, s(:const, nil, :M), :C)) # => [:M, :C] const_name(s(:const, s(:cbase), :C)) # => [nil, :C]
# File lib/rubocop/cop/rspec/described_class.rb, line 198 def const_name(node) # rubocop:disable InternalAffairs/NodeDestructuring namespace, name = *node # rubocop:enable InternalAffairs/NodeDestructuring if !namespace [name] elsif namespace.const_type? [*const_name(namespace), name] elsif %i[lvar cbase send].include?(namespace.type) [nil, name] end end
# File lib/rubocop/cop/rspec/described_class.rb, line 112 def find_usage(node, &block) yield(node) if offensive?(node) return if scope_change?(node) || node.const_type? node.each_child_node do |child| find_usage(child, &block) end end
# File lib/rubocop/cop/rspec/described_class.rb, line 166 def full_const_name(node) collapse_namespace(namespace(node), const_name(node)) end
# File lib/rubocop/cop/rspec/described_class.rb, line 122 def message(offense) if style == :described_class format(MSG, replacement: DESCRIBED_CLASS, src: offense) else format(MSG, replacement: @described_class.const_name, src: DESCRIBED_CLASS) end end
@param node [RuboCop::AST::Node] @return [Array<Symbol>] @example
namespace(node) # => [:A, :B, :C]
# File lib/rubocop/cop/rspec/described_class.rb, line 215 def namespace(node) node .each_ancestor(:class, :module) .reverse_each .flat_map { |ancestor| ancestor.defined_module_name.split('::') } .map(&:to_sym) end
# File lib/rubocop/cop/rspec/described_class.rb, line 145 def offensive?(node) if style == :described_class offensive_described_class?(node) else node.send_type? && node.method?(:described_class) end end
# File lib/rubocop/cop/rspec/described_class.rb, line 153 def offensive_described_class?(node) return unless node.const_type? # E.g. `described_class::CONSTANT` return if contains_described_class?(node) nearest_described_class, = node.each_ancestor(:block) .map { |ancestor| described_constant(ancestor) }.find(&:itself) return if nearest_described_class.equal?(node) full_const_name(nearest_described_class) == full_const_name(node) end
# File lib/rubocop/cop/rspec/described_class.rb, line 131 def scope_change?(node) scope_changing_syntax?(node) || common_instance_exec_closure?(node) || skippable_block?(node) end
# File lib/rubocop/cop/rspec/described_class.rb, line 141 def skip_blocks? cop_config['SkipBlocks'] end
# File lib/rubocop/cop/rspec/described_class.rb, line 137 def skippable_block?(node) node.block_type? && !rspec_block?(node) && skip_blocks? end