When working on a larger project, you may struggle with the problem of an increasingly growing set of tests, which over time begins to perform slower on your continuous integration (CI) server. I had this problem while working on a project in Ruby on Rails, where RSpec tests on CircleCI took about 15 minutes.
As it was bothering me, I decided to do something about it, which resulted in building an open-source Knapsack Ruby gem library (the name derives from the knapsack problem), which deals with distributing tests between parallel CI servers. In this article, you will learn about two approaches to split tests on parallel continuous integration servers - static and dynamic.