RSpec::Its provides the its method as a short-hand to specify the expected value of an attribute.

Add this line to your application's Gemfile:

gem 'rspec-its'

And then execute:

$ bundle

Or install it yourself as:

$ gem install rspec-its

And require it as:

require 'rspec/its'

Use the its method to generate a nested example group with a single example that specifies the expected value of an attribute of the subject using is_expected. The its method can also specify the block expectations of an attribute of the subject using will or will_not.

its accepts a symbol or a string, and a block representing the example.

its(:size)    { is_expected.to eq(1) }
its("length") { is_expected.to eq(1) }

You can use a string with dots to specify a nested attribute (i.e. an attribute of the attribute of the subject).

its("phone_numbers.size") { is_expected.to_not eq(0) }

The following should-style method is also available:

its(:size) { should eq(1) }

as is an alias of is_expected for pluralized use:

its(:keys) { are_expected.to eq([:key1, :key2]) }

The following block expect-style method is also available:

its(:size) { will_not raise_error }

as is this alias for pluralized use:

its(:keys) { will raise_error(NoMethodError) }

When the subject implements the [] operator, you can pass in an array with a single key to refer to the value returned by that operator when passed that key as an argument.

its([:key]) { is_expected.to eq(value) }

For hashes, multiple keys within the array will result in successive accesses into the hash. For example:

subject { {key1: {key2: 3} } }
its([:key1, :key2]) { is_expected.to eq(3) }

For other objects, multiple keys within the array will be passed as separate arguments in a single method call to [], as in:

subject { Matrix[ [:a, :b], [:c, :d] ] }
its([1,1]) { is_expected.to eq(:d) }

Metadata arguments are supported.

its(:size, focus: true) { is_expected.to eq(1) }

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