Integration Tests incorrect

[gschup]

I deleted the integration tests I previously merged. While I like the idea of having more testing not only on ggrs, but also the plugin, these tests did not correctly test what should happen. This should be fixed at some point.

[donedgardo]

I'd love to contribute for this. In general can we get a conversation going on what should be tested instead?

As a person integrating this library into their bevy game I'd like to see that:

• Systems in the Rollback stage should run.
• Rollback Components get synced between two applications with active session between each other.
• Test simple integration (great for documentation) between bevy and the plugin.
• Enough test that make us feel confident on improving the code and internal systems.

The test in the link provided would be a good start, I would remove line https://github.com/gschup/bevy_ggrs/blob/de326196cd484bbe74a0c0b7d25219fe304d7d19/tests/example_integration.rs#L29 It is not expected that the two systems are completely in sync only that both system are being scheduled and executed.

Additionally the second test would be a good candidate for the integration test and rollback behavior's: https://github.com/gschup/bevy_ggrs/blob/de326196cd484bbe74a0c0b7d25219fe304d7d19/tests/example_integration.rs#L35

Now with thanks to this helper function or something very similar, we can now also test frame by frame scenarios/edge cases:

https://github.com/johanhelsing/bevy_xpbd_jondolf/blob/0d2582fc9fb6a5324d50f922d933612a76461d30/src/tests.rs#L33

fn tick_60_fps(app: &mut App) {
    let mut update_strategy = app.world.resource_mut::<TimeUpdateStrategy>();
    let TimeUpdateStrategy::ManualInstant(prev_time) = *update_strategy else { unimplemented!() };
    *update_strategy =
        TimeUpdateStrategy::ManualInstant(prev_time + Duration::from_secs_f64(1. / 60.));
    app.update();
}

[gschup]

solved in #69 . we now have a nice basis to extend integration tests from if we wish to do so!