feat(chain): add arbitrum support (#869)

* feat: add arbitrum chainid & block explorer

* chore: update changelog

* feat: add arbitrum to is_legacy

Co-authored-by: Georgios Konstantopoulos <me@gakonst.com>

CHANGELOG.md

@@ -30,6 +30,7 @@
   [#854](https://github.com/gakonst/ethers-rs/pull/852)
 - Refactor `ethers-contract-abigen` to use `eyre` instead of `anyhow` via
   [#858](https://github.com/gakonst/ethers-rs/pull/858)
+- Add Arbitrum mainnet and testnet to the list of known chains
 
 ## ethers-contract-abigen
 

ethers-core/src/types/chain.rs

@@ -34,6 +34,8 @@ pub enum Chain {
     OptimismKovan = 69,
     BinanceSmartChain = 56,
     BinanceSmartChainTestnet = 97,
+    Arbitrum = 42161,
+    ArbitrumTestnet = 421611,
 }
 
 impl fmt::Display for Chain {
@@ -83,6 +85,8 @@ impl TryFrom<u64> for Chain {
             69 => Chain::OptimismKovan,
             56 => Chain::BinanceSmartChain,
             97 => Chain::BinanceSmartChainTestnet,
+            42161 => Chain::Arbitrum,
+            421611 => Chain::ArbitrumTestnet,
             _ => return Err(ParseChainError(chain.to_string())),
         })
     }
@@ -112,6 +116,8 @@ impl FromStr for Chain {
             "fantom-testnet" => Chain::FantomTestnet,
             "bsc" => Chain::BinanceSmartChain,
             "bsc-testnet" => Chain::BinanceSmartChainTestnet,
+            "arbitrum" => Chain::Arbitrum,
+            "arbitrum-testnet" => Chain::ArbitrumTestnet,
             _ => return Err(ParseChainError(chain.to_owned())),
         })
     }
@@ -129,7 +135,9 @@ impl Chain {
                 Chain::Fantom |
                 Chain::FantomTestnet |
                 Chain::BinanceSmartChain |
-                Chain::BinanceSmartChainTestnet
+                Chain::BinanceSmartChainTestnet |
+                Chain::Arbitrum |
+                Chain::ArbitrumTestnet,
         )
     }
 }

ethers-etherscan/src/lib.rs

@@ -80,6 +80,13 @@ impl Client {
                 Url::parse("https://api-testnet.bscscan.com/api"),
                 Url::parse("https://testnet.bscscan.com"),
             ),
+            Chain::Arbitrum => {
+                (Url::parse("https://api.arbiscan.io/api"), Url::parse("https://arbiscan.io"))
+            }
+            Chain::ArbitrumTestnet => (
+                Url::parse("https://api-testnet.arbiscan.io/api"),
+                Url::parse("https://testnet.arbiscan.io"),
+            ),
             chain => return Err(EtherscanError::ChainNotSupported(chain)),
         };
 
@@ -107,7 +114,9 @@ impl Client {
             Chain::Fantom |
             Chain::FantomTestnet |
             Chain::BinanceSmartChain |
-            Chain::BinanceSmartChainTestnet => std::env::var("ETHERSCAN_API_KEY")?,
+            Chain::BinanceSmartChainTestnet |
+            Chain::Arbitrum |
+            Chain::ArbitrumTestnet => std::env::var("ETHERSCAN_API_KEY")?,
 
             Chain::XDai | Chain::Sepolia => String::default(),
             Chain::Moonbeam | Chain::MoonbeamDev | Chain::Moonriver => {