DRYSpec introduces the let_context, subject_should_raise, and subject_should_not_raise helpers into RSpec which can allow you to have shorter, easier to read spec files.


Add this line to your application's Gemfile:

gem 'dryspec'

And then execute:

$ bundle

Or install it yourself as:

$ gem install dryspec

Then add config.extend DRYSpec::Helpers to your RSpec configuration like so:

RSpec.configure do |config|
  # ... configuration ...

  config.extend DRYSpec::Helpers

  # ... configuration ...



The let_context helper allows you to easily create a context block with one or more let variables like so:

# Before
context 'The foo is 1' do
  let(:foo) { 1 }

# After
let_context foo: 1 do

In some cases, this case even allow you to have one line per example. For example, let's say you were testing an #add_two method. You could do:

subject { add_two(value) }

let_context(value: 10) { it { should eq 12 } }
let_context(value: 1) { it { should eq 3 } }
let_context(value: 0) { it { should eq 2 } }

By default when you give let_context a Hash, the #inspect of the Hash becomes the description for your example which you see in your test output. If you'd like something more specific you can add a string like so:

let_context('Negative number', value: -1) { it { should eq 1 } }
let_context('Big negative number', value: -10) { it { should eq -8 } }


A shortcut for a combination of context and subject

let(:foo) { 55 }
let(:bar) { 66 }

# Before
context 'subject: foo' do
  subject { foo }

  it { should eq(55) }

context 'subject: bar' do
  subject { bar }

  it { should eq(66) }

# After
for_subject(:foo) { it { should eq(55) } }
for_subject(:bar) { it { should eq(66) } }

In the above the before and after are equivilent. The for_subject helper automatically generates a context with the string "subject: #{argument}".


The subject_should_raise and subject_should_not_raise are simply helpers which allow you to create an RSpec example which asserts if the subject of your tests will raise an exception. For example:

# Before
subject { fail 'Test' }
it "should raise 'Test'" do
  expect { subject }.to raise_error 'Test'

# After
subject { fail 'Test' }
subject_should_raise 'Test'

There is also a subject_should_not_raise:

subject { 1 }


See the documentation for more details


After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.


Bug reports and pull requests are welcome on GitHub at https://github.com/northwoodspd/dryspec. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.


The gem is available as open source under the terms of the MIT License.