respond_to.rb

RSpec::Support.require_rspec_support "method_signature_verifier"

module RSpec
  module Matchers
    module BuiltIn
      # @api private
      # Provides the implementation for `respond_to`.
      # Not intended to be instantiated directly.
      class RespondTo < BaseMatcher
        def initialize(*names)
          @names = names
          @expected_arity = nil
          @expected_keywords = []
          @ignoring_method_signature_failure = false
          @unlimited_arguments = nil
          @arbitrary_keywords = nil
        end

        # @api public
        # Specifies the number of expected arguments.
        #
        # @example
        #   expect(obj).to respond_to(:message).with(3).arguments
        def with(n)
          @expected_arity = n
          self
        end

        # @api public
        # Specifies keyword arguments, if any.
        #
        # @example
        #   expect(obj).to respond_to(:message).with_keywords(:color, :shape)
        # @example with an expected number of arguments
        #   expect(obj).to respond_to(:message).with(3).arguments.and_keywords(:color, :shape)
        def with_keywords(*keywords)
          @expected_keywords = keywords
          self
        end
        alias :and_keywords :with_keywords

        # @api public
        # Specifies that the method accepts any keyword, i.e. the method has
        #   a splatted keyword parameter of the form **kw_args.
        #
        # @example
        #   expect(obj).to respond_to(:message).with_any_keywords
        def with_any_keywords
          @arbitrary_keywords = true
          self
        end
        alias :and_any_keywords :with_any_keywords

        # @api public
        # Specifies that the number of arguments has no upper limit, i.e. the
        #   method has a splatted parameter of the form *args.
        #
        # @example
        #   expect(obj).to respond_to(:message).with_unlimited_arguments
        def with_unlimited_arguments
          @unlimited_arguments = true
          self
        end
        alias :and_unlimited_arguments :with_unlimited_arguments

        # @api public
        # No-op. Intended to be used as syntactic sugar when using `with`.
        #
        # @example
        #   expect(obj).to respond_to(:message).with(3).arguments
        def argument
          self
        end
        alias :arguments :argument

        # @private
        def matches?(actual)
          find_failing_method_names(actual, :reject).empty?
        end

        # @private
        def does_not_match?(actual)
          find_failing_method_names(actual, :select).empty?
        end

        # @api private
        # @return [String]
        def failure_message
          "expected #{actual_formatted} to respond to #{@failing_method_names.map { |name| description_of(name) }.join(', ')}#{with_arity}"
        end

        # @api private
        # @return [String]
        def failure_message_when_negated
          failure_message.sub(/to respond to/, 'not to respond to')
        end

        # @api private
        # @return [String]
        def description
          "respond to #{pp_names}#{with_arity}"
        end

        # @api private
        # Used by other matchers to suppress a check
        def ignoring_method_signature_failure!
          @ignoring_method_signature_failure = true
        end

      private

        def find_failing_method_names(actual, filter_method)
          @actual = actual
          @failing_method_names = @names.__send__(filter_method) do |name|
            @actual.respond_to?(name) && matches_arity?(actual, name)
          end
        end

        def matches_arity?(actual, name)
          ArityCheck.new(@expected_arity, @expected_keywords, @arbitrary_keywords, @unlimited_arguments).matches?(actual, name)
        rescue NameError
          return true if @ignoring_method_signature_failure
          raise ArgumentError, "The #{matcher_name} matcher requires that " \
                               "the actual object define the method(s) in " \
                               "order to check arity, but the method " \
                               "`#{name}` is not defined. Remove the arity " \
                               "check or define the method to continue."
        end

        def with_arity
          str = ''.dup
          str << " with #{with_arity_string}" if @expected_arity
          str << " #{str.length == 0 ? 'with' : 'and'} #{with_keywords_string}" if @expected_keywords && @expected_keywords.count > 0
          str << " #{str.length == 0 ? 'with' : 'and'} unlimited arguments" if @unlimited_arguments
          str << " #{str.length == 0 ? 'with' : 'and'} any keywords" if @arbitrary_keywords
          str
        end

        def with_arity_string
          "#{@expected_arity} argument#{@expected_arity == 1 ? '' : 's'}"
        end

        def with_keywords_string
          kw_str = case @expected_keywords.count
                   when 1
                     @expected_keywords.first.inspect
                   when 2
                     @expected_keywords.map(&:inspect).join(' and ')
                   else
                     "#{@expected_keywords[0...-1].map(&:inspect).join(', ')}, and #{@expected_keywords.last.inspect}"
                   end

          "keyword#{@expected_keywords.count == 1 ? '' : 's'} #{kw_str}"
        end

        def pp_names
          @names.length == 1 ? "##{@names.first}" : description_of(@names)
        end

        # @private
        class ArityCheck
          def initialize(expected_arity, expected_keywords, arbitrary_keywords, unlimited_arguments)
            expectation = Support::MethodSignatureExpectation.new

            if expected_arity.is_a?(Range)
              expectation.min_count = expected_arity.min
              expectation.max_count = expected_arity.max
            else
              expectation.min_count = expected_arity
            end

            expectation.keywords = expected_keywords
            expectation.expect_unlimited_arguments = unlimited_arguments
            expectation.expect_arbitrary_keywords  = arbitrary_keywords
            @expectation = expectation
          end

          def matches?(actual, name)
            return true if @expectation.empty?
            verifier_for(actual, name).with_expectation(@expectation).valid?
          end

          def verifier_for(actual, name)
            Support::StrictSignatureVerifier.new(method_signature_for(actual, name))
          end

          def method_signature_for(actual, name)
            method_handle = Support.method_handle_for(actual, name)

            if name == :new && method_handle.owner === ::Class && ::Class === actual
              Support::MethodSignature.new(actual.instance_method(:initialize))
            else
              Support::MethodSignature.new(method_handle)
            end
          end
        end
      end
    end
  end
end