fix: Lockstep versioning and test different PRNG conversions

Cargo.toml

@@ -30,8 +30,15 @@ serde = { version = "1.0", features = ["derive"], optional = true }
 rand_core = { version = "0.6", features = ["std"] }
 rand_chacha = { version = "0.3", optional = true }
 
+# This cfg cannot be enabled, but it forces Cargo to keep bevy_prng's
+# version in lockstep with bevy_rand, so that even minor versions
+# cannot be out of step with bevy_rand due to dependencies on traits
+# and implementations between the two crates.
+[target.'cfg(any())'.dependencies]
+bevy_prng = { path = "bevy_prng", version = "=0.2" }
+
 [dev-dependencies]
-bevy_prng = { path = "bevy_prng", version = "0.2", features = ["rand_chacha"] }
+bevy_prng = { path = "bevy_prng", version = "0.2", features = ["rand_chacha", "wyrand"] }
 rand = "0.8"
 ron = { version = "0.8.0", features = ["integer128"] }
 

src/resource.rs

@@ -162,7 +162,7 @@ where
 #[cfg(test)]
 mod tests {
     use bevy::reflect::TypePath;
-    use bevy_prng::{ChaCha8Rng, ChaCha12Rng};
+    use bevy_prng::{ChaCha8Rng, ChaCha12Rng, WyRand};
 
     use super::*;
 
@@ -196,7 +196,7 @@ mod tests {
     fn forking_as() {
         let mut rng1 = GlobalEntropy::<ChaCha12Rng>::default();
 
-        let rng2 = rng1.fork_as::<ChaCha8Rng>();
+        let rng2 = rng1.fork_as::<WyRand>();
 
         let rng1 = format!("{:?}", rng1);
         let rng2 = format!("{:?}", rng2);

tests/determinism.rs

@@ -1,10 +1,11 @@
 #![allow(clippy::type_complexity)]
 
 use bevy::prelude::*;
-use bevy_prng::ChaCha8Rng;
+use bevy_prng::{ChaCha8Rng, WyRand, ChaCha12Rng};
 use bevy_rand::prelude::*;
 use rand::prelude::Rng;
 
+use rand_core::RngCore;
 #[cfg(target_arch = "wasm32")]
 use wasm_bindgen_test::*;
 
@@ -23,6 +24,9 @@ struct SourceC;
 #[derive(Component)]
 struct SourceD;
 
+#[derive(Component)]
+struct SourceE;
+
 fn random_output_a(mut q_source: Query<&mut EntropyComponent<ChaCha8Rng>, With<SourceA>>) {
     let mut rng = q_source.single_mut();
 
@@ -49,24 +53,40 @@ fn random_output_c(mut q_source: Query<&mut EntropyComponent<ChaCha8Rng>, With<S
     );
 }
 
-fn random_output_d(mut q_source: Query<&mut EntropyComponent<ChaCha8Rng>, With<SourceD>>) {
+fn random_output_d(mut q_source: Query<&mut EntropyComponent<ChaCha12Rng>, With<SourceD>>) {
     let mut rng = q_source.single_mut();
 
     assert_eq!(
         rng.gen::<(u16, u16)>(),
-        (61569, 26940),
+        (41421, 7891),
         "SourceD does not match expected output"
     );
 }
 
+fn random_output_e(mut q_source: Query<&mut EntropyComponent<WyRand>, With<SourceE>>) {
+    let mut rng = q_source.single_mut();
+
+    let mut bytes = [0u8; 8];
+
+    rng.fill_bytes(bytes.as_mut());
+
+    assert_eq!(
+        &bytes,
+        &[195, 159, 73, 157, 39, 99, 104, 111],
+        "SourceE does not match expected output"
+    );
+}
+
 fn setup_sources(mut commands: Commands, mut rng: ResMut<GlobalEntropy<ChaCha8Rng>>) {
-    commands.spawn((SourceA, rng.fork_as::<ChaCha8Rng>()));
+    commands.spawn((SourceA, rng.fork_rng()));
 
     commands.spawn((SourceB, rng.fork_rng()));
 
     commands.spawn((SourceC, rng.fork_rng()));
 
-    commands.spawn((SourceD, rng.fork_rng()));
+    commands.spawn((SourceD, rng.fork_as::<ChaCha12Rng>()));
+
+    commands.spawn((SourceE, rng.fork_as::<WyRand>()));
 }
 
 /// Entities having their own sources side-steps issues with parallel execution and scheduling
@@ -91,6 +111,7 @@ fn test_parallel_determinism() {
                 random_output_b,
                 random_output_c,
                 random_output_d,
+                random_output_e,
             ),
         )
         .run();