# File lib/mocha/mock.rb, line 51
51:     def expects(method_name_or_hash, backtrace = nil)
52:       iterator = ArgumentIterator.new(method_name_or_hash)
53:       iterator.each { |*args|
54:         method_name = args.shift
55:         ensure_method_not_already_defined(method_name)
56:         expectation = Expectation.new(self, method_name, backtrace)
57:         expectation.returns(args.shift) if args.length > 0
58:         @expectations.add(expectation)
59:       }
60:     end