Contracts::Rspec

Plugin for contracts.ruby that fixes issues with rspec-mocks.

Installation

Add this line to your application's Gemfile:

gem 'contracts-rspec'

And then execute:

$ bundle

Or install it yourself as:

$ gem install contracts-rspec

Usage

Just require 'contracts/rspec' and include Contracts::RSpec::Mocks into your example group and you will be able to use enhanced instance_double:

require 'contracts'
require 'contracts/rspec'

class Example
  include Contracts

  Contract Something => Any
  def do_something(something)
    something.call
  end
end

RSpec.describe Example do
  # If you not include this, you will get ContractError, telling you
  # that `RSpec::Mocks::InstanceVerifyingDouble` is not a `Something`.
  include Contracts::RSpec::Mocks

  subject(:example) { Example.new }
  let(:something) { instance_double(Something) }

  it "works" do
    expect { example.do_something(something) }.not_to raise_error
  end
end

How it works

When you include Contracts::RSpec::Mocks, you basically make your instance_double calls additionally stub out :is_a? message, when received with specified class to return true. Which makes contract succeed.

You can do it yourself simply:

something = instance_double(Something)
allow(something).to receive(:is_a?).with(Something).and_return(true)

This library only provides a shortcut.

Contributing

1. Fork it ( https://github.com/waterlink/contracts-rspec/fork )
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 a new Pull Request