Parallel testing with Ractors - Putting CPU's to work by Vinicius Stock Parallelizing tests is an opportune way of reducing the total runtime for a test suite. Rails achieves this by forking multiple separate workers that fetch tests from a queue. In Ruby 3, Ractors introduced new mechanisms for executing code in parallel. Can they be leveraged by a test framework? And how would that compare to current parallelization solutions? Let’s find the answers to these questions by building a test framework built on Ractors, from scratch. We’ll compare the current solutions for parallelization and what advantages or limitations Ractors bring when used in this context.