add async eth.chain_id and test

docs/providers.rst

@@ -415,6 +415,7 @@ Eth
 - :meth:`web3.eth.send_transaction() <web3.eth.Eth.send_transaction>`
 - :meth:`web3.eth.send_raw_transaction() <web3.eth.Eth.send_raw_transaction>`
 - :meth:`web3.eth.hashrate <web3.eth.Eth.hashrate>`
+- :meth:`web3.eth.chain_id <web3.eth.Eth.chain_id>`
 
 Net
 ***

newsfragments/2251.feature.rst

@@ -0,0 +1 @@
+Add async ``eth.chain_id`` method

web3/_utils/module_testing/eth_module.py

@@ -688,6 +688,15 @@ async def test_async_eth_hashrate(
         assert is_integer(hashrate)
         assert hashrate >= 0
 
+    @pytest.mark.asyncio
+    async def test_async_eth_chain_id(
+        self,
+        async_w3: "Web3"
+    ) -> None:
+        chain_id = await async_w3.eth.chain_id  # type: ignore
+        # chain id value from geth fixture genesis file
+        assert chain_id == 131277322940537
+
 
 class EthModuleTest:
     def test_eth_protocol_version(self, web3: "Web3") -> None:

web3/eth.py

@@ -267,6 +267,11 @@ def call_munger(
         mungers=None,
     )
 
+    _chain_id: Method[Callable[[], int]] = Method(
+        RPC.eth_chainId,
+        mungers=None,
+    )
+
 
 class AsyncEth(BaseEth):
     is_async = True
@@ -344,6 +349,10 @@ async def coinbase(self) -> ChecksumAddress:
     async def hashrate(self) -> int:
         return await self._get_hashrate()  # type: ignore
 
+    @property
+    async def chain_id(self) -> int:
+        return await self._chain_id()  # type: ignore
+
     _get_balance: Method[Callable[..., Awaitable[Wei]]] = Method(
         RPC.eth_getBalance,
         mungers=[BaseEth.block_id_munger],
@@ -485,11 +494,6 @@ def blockNumber(self) -> BlockNumber:
         )
         return self.block_number
 
-    _chain_id: Method[Callable[[], int]] = Method(
-        RPC.eth_chainId,
-        mungers=None,
-    )
-
     @property
     def chain_id(self) -> int:
         return self._chain_id()