From 5f9ca7de3386ea7f48a74ca97594100e6e53847c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Nedim=20Salki=C4=87?= <nedim.salkic@fuel.sh>
Date: Mon, 13 Nov 2023 14:21:51 +0100
Subject: [PATCH] fix: `calculateTxChargeableBytes` when transaction has no
 witnesses (#1428)

fix: `calculateTxChargeableBytes` when transaction has no witnesses
---
 .changeset/chatty-trains-smoke.md             |  5 ++++
 .../providers/src/utils/calculate-fee.test.ts | 25 ++++++++++---------
 packages/providers/src/utils/calculate-fee.ts |  4 +--
 3 files changed, 20 insertions(+), 14 deletions(-)
 create mode 100644 .changeset/chatty-trains-smoke.md

diff --git a/.changeset/chatty-trains-smoke.md b/.changeset/chatty-trains-smoke.md
new file mode 100644
index 00000000000..55c7b29974b
--- /dev/null
+++ b/.changeset/chatty-trains-smoke.md
@@ -0,0 +1,5 @@
+---
+"@fuel-ts/providers": patch
+---
+
+Fixed calculation of chargeable bytes when transaction has no witnesses
diff --git a/packages/providers/src/utils/calculate-fee.test.ts b/packages/providers/src/utils/calculate-fee.test.ts
index eee2a652c5a..eeddb9a1c13 100644
--- a/packages/providers/src/utils/calculate-fee.test.ts
+++ b/packages/providers/src/utils/calculate-fee.test.ts
@@ -120,33 +120,34 @@ describe(__filename, () => {
   describe('calculateTxChargeableBytes', () => {
     it('should calculate properly transaction chargeable bytes just fine', () => {
       const transactionBytes = getBytesCopy(MOCK_TX_BYTES_HEX);
-      const transactionWitnesses: Witness[] = [{ dataLength: 0, data: '0x' }];
+
+      const dataLengthOffset = 8;
+      const witnessOffset = transactionBytes.length - dataLengthOffset;
+      const transactionWitnesses: Witness[] = [
+        {
+          dataLength: 0,
+          data: '0x',
+          offset: witnessOffset,
+        },
+      ];
 
       const chargeableBytesFee = calculateTxChargeableBytes({
         transactionBytes,
         transactionWitnesses,
       });
 
-      expect(chargeableBytesFee.toNumber()).toEqual(0);
+      expect(chargeableBytesFee.toNumber()).toEqual(witnessOffset);
     });
 
     it('should handle an empty witnesses array', () => {
       const transactionBytes = getBytesCopy(MOCK_TX_BYTES_HEX);
-      const offset = 520;
-      const transactionWitnesses: Witness[] = [
-        {
-          dataLength: 64,
-          data: '0x3d8943b87436d54d7f1282ed9b01d38633f8003a37676276bbaf0560390d21f826b5f6e9ea85b1bca435af2bec4982436c20c1294876025f78aaa0143867eb7f',
-          offset,
-        },
-      ];
 
       const chargeableBytesFee = calculateTxChargeableBytes({
         transactionBytes,
-        transactionWitnesses,
+        transactionWitnesses: [],
       });
 
-      expect(chargeableBytesFee.toNumber()).toEqual(520);
+      expect(chargeableBytesFee.toNumber()).toEqual(transactionBytes.length);
     });
 
     it('should round up the result', () => {
diff --git a/packages/providers/src/utils/calculate-fee.ts b/packages/providers/src/utils/calculate-fee.ts
index 0bf43246f34..8f31a856367 100644
--- a/packages/providers/src/utils/calculate-fee.ts
+++ b/packages/providers/src/utils/calculate-fee.ts
@@ -31,9 +31,9 @@ export interface CalculateTxChargeableBytesParams {
 
 /** @hidden */
 export const calculateTxChargeableBytes = (params: CalculateTxChargeableBytesParams): BN => {
-  const { transactionWitnesses } = params;
+  const { transactionWitnesses, transactionBytes } = params;
 
-  const txChargeableBytes = bn(transactionWitnesses?.[0]?.offset || 0);
+  const txChargeableBytes = bn(transactionWitnesses?.[0]?.offset || transactionBytes.length);
 
   return txChargeableBytes;
 };