This entire book is outdated and no longer maintained. I am keeping it online, in case anyone still finds any of the information in it useful. To adapt to newer versions of Bevy, please consult Bevy's migration guides.

Writing Tests for Systems

You might want to write and run automated tests for your systems.

You can use the regular Rust testing features (cargo test) with Bevy.

To do this, you can create an empty ECS World in your tests, and then, using direct World access, insert whatever entities and resources you need for testing. Create a standalone stage with the systems you want to run, and manually run it on the World.

Bevy’s official repository has a fantastic example of how to do this.