Passing parameters to an rspec shared example

Question

I have a process that returns a result set that I want to test for validity using rspec. The process will return different results based on parameters but there are many examples that are common to all of them so I would like to create a set of common examples that I can run against all of them.

I know that the preferred practice is to use let to build the result. The problem is that each process takes a minute or two to generate a result and I have probably 30 examples. With all of the permutations based on different parameters I am running about 500 examples.If I had to rebuild the result for each example the test would run more than a day.

So instead I am building a result in a before(:all) block and assigning it to an attribute something like this:

RSpec.describe 'Test Description' do
  attr_reader :result

  before(:all)
    @result = build_result({some_parameters})
  end

  context 'Some context' do
    it 'Looks lik a result' do 
      expect(result.something).to ...
    end

    it 'Feels lik a result' do 
      expect(result.something).to ...
    end
  end
end

Maybe there is a better way than using an attribute. I want to do something like this:

RSpec.describe 'Test Description' do
  attr_reader :result

  before(:all)
    @result = build_result({some_parameters})
  end

  context 'Some context' do
    it_behaves_like "A result" result
  end
end

Using an attribute in this context fails. Is there a different way to do this?

Answer 1

You can pass arguments to shared examples like this:

shared_examples_for "A result" do |argument|
 # some tests with argument
end

And then pass in my_argument like this:

it_behaves_like "A result", my_argument