Move RNG code to its own module

src/movegen/moves.rs

@@ -5,10 +5,10 @@ use crate::{
     movegen::{
         naive,
         wizardry::{
-            generate_bishop_magics, generate_rook_magics, MagicMoves, RandGen, BISHOP_SEED,
-            ROOK_SEED,
+            generate_bishop_magics, generate_rook_magics, MagicMoves, BISHOP_SEED, ROOK_SEED,
         },
     },
+    utils::RandGen,
 };
 
 // A pre-rolled RNG for magic bitboard generation, using pre-determined values.

src/movegen/wizardry/generation.rs

@@ -1,14 +1,10 @@
 use crate::board::{Bitboard, Square};
 use crate::movegen::naive::{bishop_moves, rook_moves};
+use crate::utils::RandGen;
 
 use super::mask::{generate_bishop_mask, generate_rook_mask};
 use super::Magic;
 
-/// A trait to represent RNG for u64 values.
-pub(crate) trait RandGen {
-    fn gen(&mut self) -> u64;
-}
-
 type MagicGenerationType = (Vec<Magic>, Vec<Bitboard>);
 
 pub fn generate_bishop_magics(rng: &mut dyn RandGen) -> MagicGenerationType {

src/movegen/wizardry/mod.rs

@@ -200,35 +200,7 @@ mod test {
     use std::fmt::Write as _;
 
     use super::*;
-
-    // A simple XOR-shift RNG implementation.
-    struct SimpleRng(u64);
-
-    impl SimpleRng {
-        pub fn new() -> Self {
-            Self(4) // https://xkcd.com/221/
-        }
-    }
-
-    impl RandGen for SimpleRng {
-        fn gen(&mut self) -> u64 {
-            self.0 ^= self.0 >> 12;
-            self.0 ^= self.0 << 25;
-            self.0 ^= self.0 >> 27;
-            self.0
-        }
-    }
-
-    #[test]
-    fn rng() {
-        let mut rng = SimpleRng::new();
-
-        assert_eq!(rng.gen(), 134217733);
-        assert_eq!(rng.gen(), 4504699139039237);
-        assert_eq!(rng.gen(), 13512173405898766);
-        assert_eq!(rng.gen(), 9225626310854853124);
-        assert_eq!(rng.gen(), 29836777971867270);
-    }
+    use crate::utils::SimpleRng;
 
     fn split_twice<'a>(
         text: &'a str,

src/utils/mod.rs

@@ -1,2 +1,5 @@
+pub(crate) mod rand;
+pub(crate) use rand::*;
+
 pub mod static_assert;
 pub use static_assert::*;

src/utils/rand.rs

@@ -0,0 +1,45 @@
+/// A trait to represent RNG for u64 values.
+pub trait RandGen {
+    fn gen(&mut self) -> u64;
+}
+
+// A simple XOR-shift RNG implementation, for code-generation.
+#[cfg(test)]
+pub struct SimpleRng(u64);
+
+#[cfg(test)]
+impl SimpleRng {
+    pub fn new() -> Self {
+        Self(4) // https://xkcd.com/221/
+    }
+
+    pub fn gen(&mut self) -> u64 {
+        self.0 ^= self.0 >> 12;
+        self.0 ^= self.0 << 25;
+        self.0 ^= self.0 >> 27;
+        self.0
+    }
+}
+
+#[cfg(test)]
+impl RandGen for SimpleRng {
+    fn gen(&mut self) -> u64 {
+        self.gen()
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn rng() {
+        let mut rng = SimpleRng::new();
+
+        assert_eq!(rng.gen(), 134217733);
+        assert_eq!(rng.gen(), 4504699139039237);
+        assert_eq!(rng.gen(), 13512173405898766);
+        assert_eq!(rng.gen(), 9225626310854853124);
+        assert_eq!(rng.gen(), 29836777971867270);
+    }
+}