chore: add testcase to seeded_state

Author: konippi

src/seeded_state.rs

@@ -43,6 +43,16 @@ mod tests {
 
     use crate::FxSeededState;
 
+    #[test]
+    fn same_seed_produces_same_hasher() {
+        let seed = 1;
+        let a = FxSeededState::with_seed(seed);
+        let b = FxSeededState::with_seed(seed);
+
+        // The hashers should be the same, as they have the same seed.
+        assert_eq!(a.build_hasher().hash, b.build_hasher().hash);
+    }
+
     #[test]
     fn different_states_are_different() {
         let a = FxSeededState::with_seed(1);