Implement respond_to? in module Monad

Resolves #2, as previous had no
tests.

See details in #2 PR, breifly:
Prompted by @tomstuart statement: "If this was production code, we should remember to implement #respond_to? as well."

Author: sclinede

.travis.yml

@@ -5,3 +5,6 @@ rvm:
   - 2.0.0
   - 2.1.2
 script: bundle exec rspec
+before_install:
+  - gem update --system 2.4.8
+  - gem install bundler -v 1.7.14

lib/monads/monad.rb

@@ -12,6 +12,12 @@ def method_missing(*args, &block)
       end
     end
 
+    def respond_to_missing?(method_name, include_private=false)
+      super || within do |value|
+        value.respond_to?(method_name, include_private)
+      end
+    end
+
     private
 
     def ensure_monadic_result(&block)

monads.gemspec

@@ -2,18 +2,19 @@ lib = File.expand_path('../lib', __FILE__)
 $LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
 require 'monads/version'
 
-Gem::Specification.new do |spec|
-  spec.name          = 'monads'
-  spec.version       = Monads::VERSION
-  spec.author        = 'Tom Stuart'
-  spec.email         = 'tom@codon.com'
-  spec.summary       = 'Simple Ruby implementations of some common monads.'
-  spec.homepage      = 'https://github.com/tomstuart/monads'
-  spec.license       = 'MIT'
+Gem::Specification.new do |gem|
+  gem.name          = 'monads'
+  gem.version       = Monads::VERSION
+  gem.author        = 'Tom Stuart'
+  gem.email         = 'tom@codon.com'
+  gem.summary       = 'Simple Ruby implementations of some common monads.'
+  gem.homepage      = 'https://github.com/tomstuart/monads'
+  gem.license       = 'MIT'
 
-  spec.files         = `git ls-files -z`.split("\x0")
-  spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
-  spec.require_paths = ['lib']
+  gem.files         = `git ls-files -z`.split("\x0")
+  gem.test_files    = gem.files.grep(%r{^(test|spec|features)/})
+  gem.require_paths = ['lib']
 
-  spec.add_development_dependency 'rspec', '~> 3.0', '>= 3.0.0'
+  gem.add_runtime_dependency 'bundler', '~> 1.7'
+  gem.add_development_dependency 'rspec', '~> 3.0', '>= 3.0.0'
 end

spec/monads/eventually_spec.rb

@@ -102,6 +102,8 @@ module Monads
       it 'forwards any unrecognised message to the block’s value' do
         expect(value).to receive(:challenge)
         Eventually.new { |success| success.call(value) }.challenge.run {}
+        expect { Eventually.new { |success| success.call(value) }.method(:challenge) }.not_to raise_error
+        expect(Eventually.new { |success| success.call(value) }.respond_to?(:challenge)).to be_truthy
       end
 
       it 'returns the message’s result wrapped in an Eventually' do

spec/monads/many_spec.rb

@@ -87,6 +87,8 @@ module Monads
           expect(value).to receive(:challenge)
         end
         many.challenge
+        expect { many.method(:challenge) }.not_to raise_error
+        expect(many.respond_to?(:challenge)).to be_truthy
       end
 
       it 'returns the messages’ results wrapped in a Many' do

spec/monads/optional_spec.rb

@@ -89,6 +89,8 @@ module Monads
       it 'forwards any unrecognised message to the value' do
         expect(value).to receive(:challenge)
         optional.challenge
+        expect { optional.method(:challenge) }.not_to raise_error
+        expect(optional.respond_to?(:challenge)).to be_truthy
       end
 
       it 'returns the message’s result wrapped in an Optional' do