fix(middleware): no need to multiply again with GWEI_TO_WEI_U256 (#…

…2326)

* fix(middleware): no need to multiply again with `GWEI_TO_WEI_U256`

* add tests to make sure that bug never happens again

* use the helper method to convert `f64` gwei to `U256`

* lint: make clippy happy

ethers-middleware/src/gas_oracle/etherscan.rs

@@ -1,6 +1,6 @@
-use super::{GasCategory, GasOracle, GasOracleError, Result, GWEI_TO_WEI_U256};
+use super::{GasCategory, GasOracle, GasOracleError, Result};
 use async_trait::async_trait;
-use ethers_core::{types::U256, utils::parse_units};
+use ethers_core::types::U256;
 use ethers_etherscan::Client;
 use std::ops::{Deref, DerefMut};
 
@@ -45,8 +45,8 @@ impl GasOracle for Etherscan {
             _ => unreachable!(),
         };
         // returned gas prices are f64 value in gwei
-        let gas_price = parse_units(gas_price, "gwei")?;
-        Ok(U256::from(gas_price) * GWEI_TO_WEI_U256)
+        let gas_price = super::from_gwei_f64(gas_price);
+        Ok(gas_price)
     }
 
     async fn estimate_eip1559_fees(&self) -> Result<(U256, U256)> {

ethers-middleware/tests/it/gas_oracle.rs

@@ -1,5 +1,8 @@
 use async_trait::async_trait;
-use ethers_core::{types::*, utils::Anvil};
+use ethers_core::{
+    types::*,
+    utils::{parse_ether, Anvil},
+};
 use ethers_etherscan::Client;
 use ethers_middleware::gas_oracle::{
     BlockNative, Etherchain, Etherscan, GasCategory, GasNow, GasOracle, GasOracleError,
@@ -102,6 +105,8 @@ async fn etherscan() {
 
     let gas_price = etherscan_oracle.fetch().await.unwrap();
     assert!(gas_price > U256::zero());
+    let ten_ethers = parse_ether(10).unwrap();
+    assert!(gas_price < ten_ethers, "gas calculation is wrong (too high)");
 }
 
 #[tokio::test]