no_moss

Provides a means of defining object role APIs that should be consistent between test subjects (objects under test) and test doubles (AKA mock objects).

A role provides data that can be used to verify that a test subject implements the role API. A role also provides a wrapper around a test double that prevents unsupported interactions.

Installation

Add this line to your application's Gemfile:

gem "no_moss"

And then execute:

$ bundle

Or install it yourself as:

$ gem install no_moss

Usage

Basic

Define a Role API using the NoMoss.define_role method as follows:

PersonRole = NoMoss.define_role do
  implements :id, :name, :email
end

Identify any of a role API's methods not implemented by an object (usually for unit testing purposes) using the role's unimplemented_methods_of method as follows:

PersonRole.unimplemented_methods_of(object)

Define a Role-restricted proxy to a test subject (object under test) or a test double (AKA mock object) as follows:

PersonRole.restrict(test_double)

Rspec

Enable no_moss rspec matchers by adding the following to your spec_helper file:

require 'no_moss/rspec/matchers'

... or for no_moss rspec matchers and shared examples, ...

require 'no_moss/rspec/all'

To verify that an object under test implements a role API...

it "acts like a person" do
  expect( someobject ).to play_role( RoleAPIs::Person )
end

To use a shared example to verify that the current subject implements a role API...

subject{ Fruit }
include_examples "plays the role of", RoleAPIs::FruitRepository

To enforce the role API for an object under test...

subject{ FruitRepository.restrict(Fruit) }

To enforce the role API for a test double (AKA mock object) being used as a dependency...

let(:fruit_repository){ double(:fruit_repository) }
subject{ Farm.new(
  :fruit_repository => RoleAPIs::FruitRepository.restrict(fruit_repository)
) }

Contributing

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