fix: serialize eth_getStorageAt position param as quantity (gakonst#1281

)

* fix: serialize eth_getStorageAt position param as quantity

* test: add quantity test

ethers-providers/src/provider.rs

@@ -728,12 +728,15 @@ impl<P: JsonRpcClient> Middleware for Provider<P> {
  NameOrAddress::Address(addr) => addr,
  };
 
+ // position is a QUANTITY according to the [spec](https://eth.wiki/json-rpc/API#eth_getstorageat): integer of the position in the storage, converting this to a U256
+ // will make sure the number is formatted correctly as [quantity](https://eips.ethereum.org/EIPS/eip-1474#quantity)
+ let position = U256::from_big_endian(location.as_bytes());
+ let position = utils::serialize(&position);
  let from = utils::serialize(&from);
- let location = utils::serialize(&location);
  let block = utils::serialize(&block.unwrap_or_else(|| BlockNumber::Latest.into()));
 
  // get the hex encoded value.
- let value: String = self.request("eth_getStorageAt", [from, location, block]).await?;
+ let value: String = self.request("eth_getStorageAt", [from, position, block]).await?;
  // get rid of the 0x prefix and left pad it with zeroes.
  let value = format!("{:0>64}", value.replace("0x", ""));
  Ok(H256::from_slice(&Vec::from_hex(value)?))
@@ -1526,6 +1529,22 @@ mod tests {
  };
  use futures_util::StreamExt;
 
+ #[test]
+ fn convert_h256_u256_quantity() {
+ let hash: H256 = H256::zero();
+ let quantity = U256::from_big_endian(hash.as_bytes());
+ assert_eq!(format!("{quantity:#x}"), "0x0");
+ assert_eq!(utils::serialize(&quantity).to_string(), "\"0x0\"");
+
+ let address: Address = "0x295a70b2de5e3953354a6a8344e616ed314d7251".parse().unwrap();
+ let block = BlockNumber::Latest;
+ let params =
+ [utils::serialize(&address), utils::serialize(&quantity), utils::serialize(&block)];
+
+ let params = serde_json::to_string(&params).unwrap();
+ assert_eq!(params, r#"["0x295a70b2de5e3953354a6a8344e616ed314d7251","0x0","latest"]"#);
+ }
+
  #[tokio::test]
  // Test vector from: https://docs.ethers.io/ethers.js/v5-beta/api-providers.html#id2
  async fn mainnet_resolve_name() {