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

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

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 

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 

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

• http://github.com/rspec/rspec
• http://github.com/rspec/rspec-core
• http://github.com/rspec/rspec-expectations