wtf is bevy_mod_screenshot_test?

bevy_mod_screenshot_test is a testing plugin for Bevy, a game engine written in Rust. It solves a specific problem: catching visual bugs in a game or app that regular automated tests cannot catch, especially bugs related to how things are rendered on screen. Normally, checking rendering by hand is slow and easy to get wrong, so this tool automates it with screenshot comparisons instead. Here is how it works in practice. A developer writes a short sequence of steps for the plugin to run inside the Bevy app, such as placing objects in a 3D scene and deciding exactly when to snap a picture. The plugin then launches the app, walks through those steps in order, and shuts the app down automatically once finished. The very first time a test runs, the plugin saves the screenshots it captured into an expected folder, and the developer looks at these images once to confirm they look correct before committing them to the project. On every run after that, the plugin takes new screenshots and compares them against the saved expected ones. If anything differs, the test fails, which signals that either the code broke something by accident or the visual change was intentional and the saved expected image needs to be updated. Using it requires writing Rust test files with a special configuration, since Bevy applications cannot run under Rust's normal test setup. The README includes a full code example showing how to spawn a scene, wait for shaders and assets to load, pause for a number of frames, take a screenshot, then repeat with a camera rotation change before finally validating the results. This tool is aimed at developers already building games or 3D applications with the Bevy engine who want a reliable way to catch rendering regressions in continuous integration.