For teams making frequent changes to a single codebase, CI quickly becomes a bottleneck. It's common for tests on a large codebase to take 30 min

How to Make CI Fast and Cheap with Test Impact Analysis

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2024-07-08 16:00:06

For teams making frequent changes to a single codebase, CI quickly becomes a bottleneck. It's common for tests on a large codebase to take 30 minutes, or even hours to run. Developers need this feedback as fast as possible to iterate quickly.

Teams typically do one of two things to speed up their CI pipelines: - Pay for faster machines - Pay for more machines (parallelism & test splitting)

It speeds up CI pipelines by reducing the number of tests which run on a given PR. For example, if you can determine that an incoming change to the source code only impacts one of your test files, you don't need to re-run your entire suite to validate the change.

This can lead to dramatic speedups, especially for large teams working on a single codebase, since a typical change has a relatively small impact.

Tach is a tool that lets you enforce boundaries between modules, as well as define strict interfaces for a given module. Since it understands the boundaries between your modules along with their dependencies, it can easily figure out the impact of your changes.