RSpec-Param

An RSpec helper module for writing parameterized tests with less boilerplate.

Quick Start

Add the following to your spec_helper.rb:

require 'rspec-param'
RSpec.configure do |config|
  config.include RSpecParam
end

and then use it in tests like:

define MyThing do
  param(:some_value)
  subject { MyThing.new(some_value) }

  context 'with some_value 1' do
    some_value 1
    it { ... }
  end

  context 'with some_value 2' do
    some_value 2
    it { ... }
  end
end

Using Params

Example params are super-charged let() variables. Declaring a param works like a let, either using a block to set the default value, or a normal value:

define MyThing do
  param(:with_a_block) { 'some default' }
  param(:with_a_value, 42)
end

Once set up, a param can be set in any nested context using a shorter syntax as compared to normal let variables:

define MyThing do
  param(:some_value)
  context 'with a block' do
    some_value { 1 }
  end
  context 'with a value' do
    some_value 1
  end
end

Anywhere inside an example or RSpec helper that you would use a let variable, you can use a param instead.

Accumulators

As a special mode, you can tell a param to accumulate all values from each context rather than overriding the value:

define MyThing do
  param(:some_value)
  context 'inner' do
    some_value 1
    it { expect(some_value).to eq [1] }
    context 'more inner' do
      some_value { 2 }
      it { expect(some_value).to eq [1, 2] }
    end
  end
end

Sponsors

Development sponsored by Bloomberg.

License

Copyright 2016, Noah Kantrowitz

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.