From f9d115ae75846d6bbe578ca14eb7e36f8c98917a Mon Sep 17 00:00:00 2001
From: Mark Spanbroek <mark@spanbroek.net>
Date: Mon, 14 Apr 2025 12:51:54 +0200
Subject: [PATCH] Use pending block for gas estimations

---
 ethers/contracts/gas.nim         | 11 +++++++---
 testmodule/testGasEstimation.nim | 36 +++++++++++++++++++++++++++++++-
 2 files changed, 43 insertions(+), 4 deletions(-)

diff --git a/ethers/contracts/gas.nim b/ethers/contracts/gas.nim
index 7ef3ec3..703b1c5 100644
--- a/ethers/contracts/gas.nim
+++ b/ethers/contracts/gas.nim
@@ -5,6 +5,7 @@ import ../signer
 import ./contract
 import ./contractcall
 import ./transactions
+import ./overrides
 import ./errors
 import ./syntax
 
@@ -16,11 +17,15 @@ func estimateGas*[C: Contract](contract: C): ContractGasEstimations[C] =
 proc estimateGas(
   call: ContractCall
 ): Future[UInt256] {.async: (raises: [CancelledError, ProviderError, EthersError]).} =
-  var transaction = createTransaction(call)
+  let transaction = createTransaction(call)
+  var blockTag = BlockTag.pending
+  if call.overrides of CallOverrides:
+    if tag =? CallOverrides(call.overrides).blockTag:
+      blockTag = tag
   if signer =? call.contract.signer:
-    await signer.estimateGas(transaction)
+    await signer.estimateGas(transaction, blockTag)
   else:
-    await call.contract.provider.estimateGas(transaction)
+    await call.contract.provider.estimateGas(transaction, blockTag)
 
 func wrapFirstParameter(procedure: var NimNode) =
   let contractType = procedure.params[1][1]
diff --git a/testmodule/testGasEstimation.nim b/testmodule/testGasEstimation.nim
index 7efdd50..3b01a35 100644
--- a/testmodule/testGasEstimation.nim
+++ b/testmodule/testGasEstimation.nim
@@ -28,7 +28,7 @@ suite "gas estimation":
     discard await provider.send("evm_revert", @[snapshot])
     await provider.close()
 
-  test "uses pending block for gas estimations":
+  test "contract function calls use pending block for gas estimations":
     let latest = CallOverrides(blockTag: some BlockTag.latest)
     let pending = CallOverrides(blockTag: some BlockTag.pending)
 
@@ -41,3 +41,37 @@ suite "gas estimation":
     # fails with "Transaction ran out of gas" when gas estimation
     # is not done using the pending block
     await contract.checkTimeEquals(time)
+
+  test "contract gas estimation uses pending block":
+    let latest = CallOverrides(blockTag: some BlockTag.latest)
+    let pending = CallOverrides(blockTag: some BlockTag.pending)
+
+    # retrieve time of pending block
+    let time = await contract.getTime(overrides=pending)
+
+    # ensure that time of latest block and pending block differ
+    check (await contract.getTime(overrides=latest)) != time
+
+    # estimate gas
+    let gas = await contract.estimateGas.checkTimeEquals(time)
+    let overrides = TransactionOverrides(gasLimit: some gas)
+
+    # fails with "Transaction ran out of gas" when gas estimation
+    # was not done using the pending block
+    await contract.checkTimeEquals(time, overrides)
+
+  test "contract gas estimation honors a block tag override":
+    let latest = CallOverrides(blockTag: some BlockTag.latest)
+    let pending = CallOverrides(blockTag: some BlockTag.pending)
+
+    # retrieve time of pending block
+    let time = await contract.getTime(overrides=pending)
+
+    # ensure that time of latest block and pending block differ
+    check (await contract.getTime(overrides=latest)) != time
+
+    # estimate gas
+    let gasLatest = await contract.estimateGas.checkTimeEquals(time, latest)
+    let gasPending = await contract.estimateGas.checkTimeEquals(time, pending)
+
+    check gasLatest != gasPending