⚪ ️5.4 Parallelize test execution
:white_check_mark: Do: When done right, testing is your 24/7 friend providing almost instant feedback. In practice, executing 500 CPU-bounded unit test on a single thread can take too long. Luckily, modern test runners and CI platforms (like Jest, AVA and Mocha extensions) can parallelize the test into multiple processes and achieve significant improvement in feedback time. Some CI vendors do also parallelize tests across containers (!) which shortens the feedback loop even further. Whether locally over multiple processes, or over some cloud CLI using multiple machines — parallelizing demand keeping the tests autonomous as each might run on different processes
❌ Otherwise: Getting test results 1 hour long after pushing new code, as you already code the next features, is a great recipe for making testing less relevant
✏ Code Examples
:clap: Doing It Right Example: Mocha parallel & Jest easily outrun the traditional Mocha thanks to testing parallelization (Credit: JavaScript Test-Runners Benchmark)
