Spark Joy by Running Fewer Tests – Shopify Engineering

Developers write tests to ensure correctness and allow future changes to be made safely. However, as the number of features grows, so does the number of tests. Tests are a double-edged sword. On one hand, well-written ones catch bugs and maintain a program’s stability, but as the code base grows, a high number of tests impedes scalability because they take a long time to run and increase the likelihood of intermittently failing tests. Software projects often require all tests to pass before merging to master. This adds overhead to all developers. Intermittently failing tests worsen the problem. Some causes of intermittently failing tests are.