feat: add serde derives for CacheDB under "serde" flag

crates/revm/src/db/emptydb.rs

@@ -10,6 +10,7 @@ pub type EmptyDB = EmptyDBTyped<Infallible>;
 /// An empty database that always returns default values when queried.
 ///
 /// This is generic over a type which is used as the database error type.
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub struct EmptyDBTyped<E> {
     _phantom: PhantomData<E>,
 }

crates/revm/src/db/in_memory_db.rs

@@ -18,6 +18,7 @@ pub type InMemoryDB = CacheDB<EmptyDB>;
 /// whereas contracts are identified by their code hash, and are stored in the `contracts` map.
 /// The [DbAccount] holds the code hash of the contract, which is used to look up the contract in the `contracts` map.
 #[derive(Debug, Clone)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub struct CacheDB<ExtDB: DatabaseRef> {
     /// Account info where None means it is not existing. Not existing state is needed for Pre TANGERINE forks.
     /// `code` is always `None`, and bytecode can be found in `contracts`.
@@ -288,6 +289,7 @@ impl<ExtDB: DatabaseRef> DatabaseRef for CacheDB<ExtDB> {
 }
 
 #[derive(Debug, Clone, Default)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub struct DbAccount {
     pub info: AccountInfo,
     /// If account is selfdestructed or newly created, storage will be cleared.
@@ -330,6 +332,7 @@ impl From<AccountInfo> for DbAccount {
 }
 
 #[derive(Debug, Clone, Default, PartialEq, Eq, Hash)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub enum AccountState {
     /// Before Spurious Dragon hardfork there was a difference between empty and not existing.
     /// And we are flagging it here.
@@ -453,4 +456,28 @@ mod tests {
         assert_eq!(new_state.storage(account, key0), Ok(U256::ZERO));
         assert_eq!(new_state.storage(account, key1), Ok(value1));
     }
+
+    #[cfg(feature = "serde")]
+    #[test]
+    fn test_serialize_deserialize_cachedb() {
+        let account = Address::with_last_byte(69);
+        let nonce = 420;
+        let mut init_state = CacheDB::new(EmptyDB::default());
+        init_state.insert_account_info(
+            account,
+            AccountInfo {
+                nonce,
+                ..Default::default()
+            },
+        );
+
+        let serialized = serde_json::to_string(&init_state).unwrap();
+        let deserialized: CacheDB<EmptyDB> = serde_json::from_str(&serialized).unwrap();
+
+        assert!(deserialized.accounts.get(&account).is_some());
+        assert_eq!(
+            deserialized.accounts.get(&account).unwrap().info.nonce,
+            nonce
+        );
+    }
 }