RSpec::CollectionMatchers

RSpec::CollectionMatchers lets you express expected outcomes on collections of an object in an example.

expect(account.shopping_cart).to have_exactly(3).items

Install

Add this line to your application's Gemfile:

gem 'rspec-collection_matchers'

And then execute:

$ bundle

Or install it yourself as:

$ gem install rspec-collection_matchers

Basic usage

First of all, you need to require rspec-collection matchers. Add the following line to your spec_helper.rb:

require 'rspec/collection_matchers'

Using rspec-collection_matchers you can match the number of items in a collection directly, e.g.:

it 'matches number of items in a collection' do
  expect([1,2,3]).to have_at_least(3).items
end

You can also match the number of items returned by a method on an object, e.g.:

class Cart
  def initialize(*products)
    @products = products
  end
  attr_reader :products
end

it 'matches number of items returned from a method' do
  cart = Cart.new('product a', 'product b')
  expect(cart).to have_at_most(2).products
end

The last line of the example expresses an expected outcome: if cart.products.size <= 2 then the example passes, otherwise it fails with a message like:

expected at most 2 products, got 3

Available matchers

expect(collection).to have(n).items
expect(collection).to have_exactly(n).items
expect(collection).to have_at_most(n).items
expect(collection).to have_at_least(n).items
expect(collection).to have(:no).items