From a29e86bfc8f2cfafa055259fa9b902bc16f161a3 Mon Sep 17 00:00:00 2001
From: Mark Spanbroek <mark@spanbroek.net>
Date: Thu, 10 Apr 2025 09:47:16 +0200
Subject: [PATCH] Handle custom errors when estimating gas

---
 ethers/contracts/gas.nim        |  3 ++-
 testmodule/testCustomErrors.nim | 14 +++++++++++++-
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/ethers/contracts/gas.nim b/ethers/contracts/gas.nim
index e90bb89..7ef3ec3 100644
--- a/ethers/contracts/gas.nim
+++ b/ethers/contracts/gas.nim
@@ -5,6 +5,7 @@ import ../signer
 import ./contract
 import ./contractcall
 import ./transactions
+import ./errors
 import ./syntax
 
 type ContractGasEstimations[C] = distinct C
@@ -42,4 +43,4 @@ func createGasEstimationCall*(procedure: NimNode): NimNode =
   result.addAsyncPragma()
   result.addUsedPragma()
   result.addEstimateCall()
-
+  result.addErrorHandling()
diff --git a/testmodule/testCustomErrors.nim b/testmodule/testCustomErrors.nim
index f35abfd..884bc31 100644
--- a/testmodule/testCustomErrors.nim
+++ b/testmodule/testCustomErrors.nim
@@ -97,7 +97,7 @@ suite "Contract custom errors":
     expect ErrorWithArguments:
       await contract.revertsMultipleErrors(simple = false)
 
-  test "handles gas estimation errors":
+  test "handles gas estimation errors when calling a contract function":
     proc revertsTransaction(contract: TestCustomErrors)
       {.contract, errors:[ErrorWithArguments].}
 
@@ -109,6 +109,18 @@ suite "Contract custom errors":
       check error.arguments.one == 1.u256
       check error.arguments.two == true
 
+  test "handles errors when only doing gas estimation":
+    proc revertsTransaction(contract: TestCustomErrors)
+      {.contract, errors:[ErrorWithArguments], used.}
+
+    let contract = contract.connect(provider.getSigner())
+    try:
+      discard await contract.estimateGas.revertsTransaction()
+      fail()
+    except ErrorWithArguments as error:
+      check error.arguments.one == 1.u256
+      check error.arguments.two == true
+
   test "handles transaction submission errors":
     proc revertsTransaction(contract: TestCustomErrors)
       {.contract, errors:[ErrorWithArguments].}