# Objective
- Make the example deterministic when run with CI, so that the
[screenshot
comparison](https://thebevyflock.github.io/bevy-example-runner/) is
stable
- Preserve the "truly random on each run" behavior so that every page
load in the example showcase shows a different contributor first
## Solution
- Fall back to the static default contributor list in CI
- Store contributors in a `Vec` so that we can show repeats of the
fallback contributor list, giving the appearance of lots of overlapping
contributors in CI
- Use a shared seeded RNG throughout the app
- Give contributor birds a `z` value so that their depth is stable
- Remove the shuffle, which was redundant because contributors are first
collected into a hashmap
- `chain` the systems so that the physics is deterministic from run to
run
## Testing
```bash
echo '(setup: (fixed_frame_time: Some(0.05)), events: [(100, Screenshot), (500, AppExit)])' > config.ron
CI_TESTING_CONFIG=config.ron cargo run --example contributors --features=bevy_ci_testing
mv screenshot-100.png screenshot-100-a.png
CI_TESTING_CONFIG=config.ron cargo run --example contributors --features=bevy_ci_testing
diff screenshot-100.png screenshot-100-a.png
```
## Alternatives
I'd also be fine with removing this example from the list of examples
that gets screenshot-tested in CI. Coverage from other 2d examples is
probably adequate.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
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