RSpec: How to test for a boolean return type?

Question

I'm using RSpec to test an API. I want to specify that one particular endpoint returns a boolean value, either true or false. This is an API to be used by other systems and languages, and so it's important for it to be an actual boolean, not merely something that Ruby will evaluate to false or true.

But I don't see a way to do this because there's no Boolean type in Ruby.

Answer 1

expect(variable).to be_in([true, false]) 

Answer 2

I had the same problem. This is what I came up with:

RSpec::Matchers.define :be_boolean do   match do |actual|     expect(actual).to be_in([true, false])   end end 

See: https://www.relishapp.com/rspec/rspec-expectations/v/3-4/docs/custom-matchers

It can be used like so:

it 'is boolean' do   expect(true).to be_boolean end