Add Signer.signMessage()

ethers/providers/jsonrpc.nim

@@ -102,6 +102,12 @@ method getAddress*(signer: JsonRpcSigner): Future[Address] {.async.} =
 
   raiseProviderError "no address found"
 
+method signMessage*(signer: JsonRpcSigner,
+                    message: seq[byte]): Future[seq[byte]] {.async.} =
+  let client = await signer.provider.client
+  let address = await signer.getAddress()
+  return await client.eth_sign(address, message)
+
 method sendTransaction*(signer: JsonRpcSigner,
                         transaction: Transaction) {.async.} =
   let client = await signer.provider.client

ethers/providers/rpccalls/signatures.nim

@@ -7,3 +7,4 @@ proc eth_getTransactionCount(address: Address, blockTag: BlockTag): UInt256
 proc eth_estimateGas(transaction: Transaction): UInt256
 proc eth_chainId(): UInt256
 proc eth_sendTransaction(transaction: Transaction): array[32, byte]
+proc eth_sign(account: Address, message: seq[byte]): seq[byte]

ethers/signer.nim

@@ -15,6 +15,10 @@ method provider*(signer: Signer): Provider {.base.} =
 method getAddress*(signer: Signer): Future[Address] {.base.} =
   doAssert false, "not implemented"
 
+method signMessage*(signer: Signer,
+                    message: seq[byte]): Future[seq[byte]] {.base, async.} =
+  doAssert false, "not implemented"
+
 method sendTransaction*(signer: Signer,
                         transaction: Transaction) {.base, async.} =
   doAssert false, "not implemented"

testmodule/testJsonRpcSigner.nim

@@ -1,5 +1,6 @@
 import pkg/asynctest
 import pkg/ethers
+import pkg/stew/byteutils
 import ./examples
 
 suite "JsonRpcSigner":
@@ -39,6 +40,11 @@ suite "JsonRpcSigner":
     let chainId = await signer.getChainId()
     check chainId == 31337.u256 # hardhat chain id
 
+  test "can sign messages":
+    let signer = provider.getSigner()
+    let message = "hello".toBytes
+    check (await signer.signMessage(message)).len == 65
+
   test "can populate missing fields in a transaction":
     let signer = provider.getSigner()
     let transaction = Transaction.example