Add poseidon-lengths test

poseidon-lengths/rs/src/lib.rs

@@ -0,0 +1,17 @@
+#[cfg(test)]
+mod tests {
+    use poseidon_rs::Poseidon;
+    use rustc_hex::ToHex;
+
+    #[test]
+    fn test_output_size() {
+        let poseidon = Poseidon::new();
+        let msg = "45";
+        let h = poseidon.hash_bytes(msg.as_bytes().to_vec()).unwrap();
+        println!("bigint {:?}", h.to_string());
+        println!("length {:?}", h.to_bytes_be().1.len());
+        println!("bytes {:?}", h.to_bytes_be().1);
+        assert_eq!(h.to_bytes_be().1.len(), 31);
+        println!("hex {:?}", h.to_bytes_be().1.to_hex());
+    }
+}