Output validations when help is invoked

lib/thor/base.rb

@@ -524,6 +524,7 @@ def print_options(shell, options, group_name = nil)
             list << item
             list << ["", "# Default: #{option.default}"] if option.show_default?
             list << ["", "# Possible values: #{option.enum.join(', ')}"] if option.enum
+            list << ["", "# Validation: #{option.validator_description}"] if option.validator_description
           end
         end
 

spec/fixtures/script.thor

@@ -91,6 +91,12 @@ END
     [name, options, args]
   end
 
+  method_option :my_option, :type => :string, :validator => proc { |v| v == 'hello world' }, :validator_desc => 'Needs to be "hello world"'
+  desc 'with_validator', 'Check option with validator'
+  def with_validator
+    [options]
+  end
+
   class AnotherScript < Thor
     desc "baz", "do some bazing"
     def baz

spec/thor_spec.rb

@@ -384,6 +384,10 @@ def shell
 END
       end
 
+      it "outputs information about validations as well" do
+        expect(capture(:stdout) { MyScript.command_help(shell, "with_validator") }).to include 'Validation'
+      end
+
       it "raises an error if the command can't be found" do
         expect do
           MyScript.command_help(shell, "unknown")