From 8166d5057860cc11e03342e37e9a64a9647cb61c Mon Sep 17 00:00:00 2001
From: Daniel <80175477+dan437@users.noreply.github.com>
Date: Tue, 8 Feb 2022 19:14:50 +0100
Subject: [PATCH] Resolve a BigNumber issue (#13555)

* Do not call `decimalToHex` for `minimumGasLimit`, which is already in hex

* Add `0x` prefix when returning a gas estimate

* Fix UTs

Co-authored-by: Dan J Miller <danjm.com@gmail.com>
---
 app/scripts/controllers/swaps.js        | 2 +-
 app/scripts/controllers/swaps.test.js   | 6 ++++--
 ui/hooks/gasFeeInput/useGasEstimates.js | 2 +-
 3 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/app/scripts/controllers/swaps.js b/app/scripts/controllers/swaps.js
index 5e8fb6990..e3d0198e4 100644
--- a/app/scripts/controllers/swaps.js
+++ b/app/scripts/controllers/swaps.js
@@ -55,7 +55,7 @@ function calculateGasEstimateWithRefund(
 
   const gasEstimateWithRefund =
     !isMaxGasMinusRefundNegative && maxGasMinusRefund.lt(estimatedGas, 16)
-      ? maxGasMinusRefund.toString(16)
+      ? `0x${maxGasMinusRefund.toString(16)}`
       : estimatedGas;
 
   return gasEstimateWithRefund;
diff --git a/app/scripts/controllers/swaps.test.js b/app/scripts/controllers/swaps.test.js
index 3bc5b4e0d..85890eeb2 100644
--- a/app/scripts/controllers/swaps.test.js
+++ b/app/scripts/controllers/swaps.test.js
@@ -372,7 +372,9 @@ describe('SwapsController', function () {
         assert.strictEqual(gasEstimate, bufferedGasLimit);
         assert.strictEqual(
           gasEstimateWithRefund,
-          new BigNumber(maxGas, 10).minus(estimatedRefund, 10).toString(16),
+          `0x${new BigNumber(maxGas, 10)
+            .minus(estimatedRefund, 10)
+            .toString(16)}`,
         );
       });
 
@@ -690,7 +692,7 @@ describe('SwapsController', function () {
           isBestQuote: true,
           // TODO: find a way to calculate these values dynamically
           gasEstimate: 2000000,
-          gasEstimateWithRefund: 'b8cae',
+          gasEstimateWithRefund: '0xb8cae',
           savings: {
             fee: '0',
             metaMaskFee: '0.5050505050505050505',
diff --git a/ui/hooks/gasFeeInput/useGasEstimates.js b/ui/hooks/gasFeeInput/useGasEstimates.js
index 5466ec584..0eb0c65e9 100644
--- a/ui/hooks/gasFeeInput/useGasEstimates.js
+++ b/ui/hooks/gasFeeInput/useGasEstimates.js
@@ -111,7 +111,7 @@ export function useGasEstimates({
   const maximumCostInHexWei = getMaximumGasTotalInHexWei(gasSettings);
 
   if (editGasMode === EDIT_GAS_MODES.SWAPS) {
-    gasSettings = { ...gasSettings, gasLimit: decimalToHex(minimumGasLimit) };
+    gasSettings = { ...gasSettings, gasLimit: minimumGasLimit };
   }
 
   // The minimum amount this transaction will cost