A DSL for validating input for methods

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Add this line to your application’s Gemfile:

gem 'expects'

And then execute:

$ bundle

Or install it yourself as:

$ gem install expects


Include Expects in your class and then call it in your methods eg:

ruby class YourClass include Expects

def initialize(name) expects name, String end end You can pass an array instead of one class to accept multiple types e.g.

ruby expects number, [Fixnum, Float]

If you try to pass anything other than a string to YourClass.new expects will raise an exception which you can catch like so:

ruby begin YourClass.new(1234) rescue UnexpectedInput => e e.message # Expected 1234 to be String e.subject # 1234 e.expected # [String] end

All exceptions thrown by expects are instances of UnexpectedInput


  1. Fork it
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request