Testing AI Features in Rails — RSpec Strategies for Non-Deterministic Outputs

Welcome back to the Ruby for AI series. You've built AI features — chat interfaces, RAG pipelines, image generation, voice transcription. Now comes the part most tutorials skip: how do you test code that returns different results every time you call it? AI outputs are non-deterministic. Ask the same question twice, get two different answers. Traditional "assert equals" testing breaks down. But that doesn't mean you skip tests. It means you test smarter. Let's set up a proper testing strategy for AI-powered Rails apps. Setting Up RSpec If you haven't already: bundle add rspec-rails --group "development, test" bundle add webmock --group test bundle add vcr --group test rails generate rspec:install Add to spec/rails_helper.rb : require 'webmock/rspec' require 'vcr' VCR . configure do | config | config . cassette_library_dir = 'spec/cassettes' config . hook_into :webmock config . filter_sensitive_data ( '<OPENAI_KEY>' ) { ENV [ 'OPENAI_API_KEY' ] } config . default_cassette_options = { rec