Add replay for failed txs to get revert reason

ethers/contract.nim

@@ -252,7 +252,24 @@ proc confirm*(tx: Future[?TransactionResponse],
       "Transaction hash required. Possibly was a call instead of a send?"
     )
 
-  return await response.confirm(confirmations, timeout)
+  let receipt = await response.confirm(confirmations, timeout)
+
+  echo "[ether/contract.confirm] receipt.status: ", receipt.status
+  if receipt.status != TransactionStatus.Success:
+    without blockNumber =? receipt.blockNumber:
+      raiseContractError "Transaction reverted with unknown reason"
+
+    let provider = response.provider
+    without transaction =? await provider.getTransaction(receipt.transactionHash):
+      raiseContractError "Transaction reverted with unknown reason"
+
+    try:
+      await provider.replay(transaction, blockNumber)
+    except ProviderError as e:
+      # should contain the revert reason
+      raiseContractError e.msg
+
+  return receipt
 
 proc queryFilter[E: Event](contract: Contract,
                             _: type E,

ethers/provider.nim

@@ -79,6 +79,11 @@ method getTransactionCount*(provider: Provider,
                            Future[UInt256] {.base, gcsafe.} =
   doAssert false, "not implemented"
 
+method getTransaction*(provider: Provider,
+                       txHash: TransactionHash):
+                      Future[?Transaction] {.base, gcsafe.} =
+  doAssert false, "not implemented"
+
 method getTransactionReceipt*(provider: Provider,
                             txHash: TransactionHash):
                            Future[?TransactionReceipt] {.base, gcsafe.} =
@@ -114,6 +119,16 @@ method subscribe*(provider: Provider,
 method unsubscribe*(subscription: Subscription) {.base, async.} =
   doAssert false, "not implemented"
 
+proc replay*(provider: Provider, tx: Transaction, blockNumber: UInt256) {.async.} =
+  # Replay transaction at block. Useful for fetching revert reasons, which will
+  # be present in the raised error message. The replayed block number should
+  # include the state of the chain in the block previous to the block in which
+  # the transaction was mined. This means that transactions that were mined in
+  # the same block BEFORE this transaction will not have their state transitions
+  # included in the replay.
+  # More information: https://snakecharmers.ethereum.org/web3py-revert-reason-parsing/
+  discard await provider.call(tx, BlockTag.init(blockNumber - 1))
+
 proc confirm*(tx: TransactionResponse,
               confirmations = EthersDefaultConfirmations,
               timeout = EthersReceiptTimeoutBlks):

ethers/providers/jsonrpc.nim

@@ -152,6 +152,13 @@ method getTransactionCount*(provider: JsonRpcProvider,
     let client = await provider.client
     return await client.eth_getTransactionCount(address, blockTag)
 
+method getTransaction*(provider: JsonRpcProvider,
+                       txHash: TransactionHash):
+                      Future[?Transaction] {.async.} =
+  convertError:
+    let client = await provider.client
+    return await client.eth_getTransactionByHash(txHash)
+
 method getTransactionReceipt*(provider: JsonRpcProvider,
                               txHash: TransactionHash):
                              Future[?TransactionReceipt] {.async.} =

ethers/providers/jsonrpc/signatures.nim

@@ -5,6 +5,7 @@ proc eth_call(transaction: Transaction, blockTag: BlockTag): seq[byte]
 proc eth_gasPrice(): UInt256
 proc eth_getBlockByNumber(blockTag: BlockTag, includeTransactions: bool): ?Block
 proc eth_getLogs(filter: EventFilter | Filter | FilterByBlockHash): JsonNode
+proc eth_getTransactionByHash(hash: BlockHash): ?Transaction
 proc eth_getBlockByHash(hash: BlockHash, includeTransactions: bool): ?Block
 proc eth_getTransactionCount(address: Address, blockTag: BlockTag): UInt256
 proc eth_estimateGas(transaction: Transaction): UInt256

testmodule/testContracts.nim

@@ -5,6 +5,7 @@ import pkg/questionable
 import pkg/stint
 import pkg/ethers
 import pkg/ethers/erc20
+import pkg/ethers/testing
 import ./hardhat
 import ./helpers
 import ./miner