rspec/rspec-expectations

module RSpec
  module Matchers
    module BuiltIn
      # @api private
      # Provides the implementation for `throw_symbol`.
      # Not intended to be instantiated directly.
      class ThrowSymbol
        include Composable

        def initialize(expected_symbol=nil, expected_arg=nil)
          @expected_symbol = expected_symbol
          @expected_arg = expected_arg
          @caught_symbol = @caught_arg = nil
        end

        # rubocop:disable MethodLength
        # @private
        def matches?(given_proc)
          @block = given_proc
          return false unless Proc === given_proc

          begin
            if @expected_symbol.nil?
              given_proc.call
            else
              @caught_arg = catch :proc_did_not_throw_anything do
                catch @expected_symbol do
                  given_proc.call
                  throw :proc_did_not_throw_anything, :nothing_thrown
                end
              end

              if @caught_arg == :nothing_thrown
                @caught_arg = nil
              else
                @caught_symbol = @expected_symbol
              end
            end

            # Ruby 1.8 uses NameError with `symbol'
            # Ruby 1.9 uses ArgumentError with :symbol
          rescue NameError, ArgumentError => e
            unless (match_data = e.message.match(/uncaught throw (`|\:)([a-zA-Z0-9_]*)(')?/))
              other_exception = e
              raise
            end
            @caught_symbol = match_data.captures[1].to_sym
          rescue => other_exception
            raise
          ensure
            # rubocop:disable EnsureReturn
            unless other_exception
              if @expected_symbol.nil?
                return !!@caught_symbol
              else
                if @expected_arg.nil?
                  return @caught_symbol == @expected_symbol
                else
                  return (@caught_symbol == @expected_symbol) && values_match?(@expected_arg, @caught_arg)
                end
              end
            end
            # rubocop:enable EnsureReturn
          end
        end
        # rubocop:enable MethodLength

        def does_not_match?(given_proc)
          !matches?(given_proc) && Proc === given_proc
        end

        # @api private
        # @return [String]
        def failure_message
          "expected #{expected} to be thrown, #{actual_result}"
        end

        # @api private
        # @return [String]
        def failure_message_when_negated
          "expected #{expected('no Symbol')}#{' not' if @expected_symbol} to be thrown, #{actual_result}"
        end

        # @api private
        # @return [String]
        def description
          "throw #{expected}"
        end

        # @api private
        # Indicates this matcher matches against a block.
        # @return [True]
        def supports_block_expectations?
          true
        end

        def expects_call_stack_jump?
          true
        end

      private

        def actual_result
          return "but was not a block" unless Proc === @block
          "got #{caught}"
        end

        def expected(symbol_desc='a Symbol')
          throw_description(@expected_symbol || symbol_desc, @expected_arg)
        end

        def caught
          throw_description(@caught_symbol || 'nothing', @caught_arg)
        end

        def throw_description(symbol, arg)
          symbol_description = symbol.is_a?(String) ? symbol : description_of(symbol)

          arg_description = if arg
                              " with #{description_of arg}"
                            elsif @expected_arg && @caught_symbol == @expected_symbol
                              " with no argument"
                            else
                              ""
                            end

          symbol_description + arg_description
        end
      end
    end
  end
end