fix(TXL-399): Use contract abi to decode the amounts of token balance changes

packages/transaction-controller/jest.config.js

@@ -18,9 +18,9 @@ module.exports = merge(baseConfig, {
   coverageThreshold: {
     global: {
       branches: 94.42,
-      functions: 97.46,
-      lines: 98.44,
-      statements: 98.46,
+      functions: 97.45,
+      lines: 98.37,
+      statements: 98.38,
     },
   },
 

packages/transaction-controller/src/utils/simulation.test.ts

@@ -1,5 +1,6 @@
 import type { LogDescription } from '@ethersproject/abi';
 import { Interface } from '@ethersproject/abi';
+import { type Hex } from '@metamask/utils';
 
 import {
   SimulationInvalidResponseError,
@@ -11,27 +12,45 @@ import {
   SupportedToken,
   type GetSimulationDataRequest,
 } from './simulation';
-import type { SimulationResponseLog } from './simulation-api';
+import type {
+  SimulationResponseLog,
+  SimulationResponseTransaction,
+} from './simulation-api';
 import {
   simulateTransactions,
   type SimulationResponse,
 } from './simulation-api';
 
 jest.mock('./simulation-api');
 
-const USER_ADDRESS_MOCK = '0x123';
-const OTHER_ADDRESS_MOCK = '0x456';
-const CONTRACT_ADDRESS_1_MOCK = '0x789';
-const CONTRACT_ADDRESS_2_MOCK = '0xDEF';
-const BALANCE_1_MOCK = '0x0';
-const BALANCE_2_MOCK = '0x1';
-const DIFFERENCE_MOCK = '0x1';
-const VALUE_MOCK = '0x4';
-const TOKEN_ID_MOCK = '0x5';
-const OTHER_TOKEN_ID_MOCK = '0x6';
+// Utility function to encode addresses and values to 32-byte ABI format
+const encodeTo32ByteHex = (value: string | number): Hex => {
+  // Pad to 32 bytes (64 characters) and add '0x' prefix
+  return `0x${BigInt(value).toString(16).padStart(64, '0')}`;
+};
+
+// getSimulationData returns values in hex format with leading zeros trimmed.
+const trimLeadingZeros = (hexString: Hex): Hex => {
+  const trimmed = hexString.replace(/^0x0+/u, '0x') as Hex;
+  return trimmed === '0x' ? '0x0' : trimmed;
+};
+
+const USER_ADDRESS_MOCK = '0x123' as Hex;
+const OTHER_ADDRESS_MOCK = '0x456' as Hex;
+const CONTRACT_ADDRESS_1_MOCK = '0x789' as Hex;
+const CONTRACT_ADDRESS_2_MOCK = '0xDEF' as Hex;
+const BALANCE_1_MOCK = '0x0' as Hex;
+const BALANCE_2_MOCK = '0x1' as Hex;
+const DIFFERENCE_MOCK = '0x1' as Hex;
+const VALUE_MOCK = '0x4' as Hex;
+const TOKEN_ID_MOCK = '0x5' as Hex;
+const OTHER_TOKEN_ID_MOCK = '0x6' as Hex;
 const ERROR_CODE_MOCK = 123;
 const ERROR_MESSAGE_MOCK = 'Test Error';
 
+// Regression test – leading zero in user address
+const USER_ADDRESS_WITH_LEADING_ZEROS = '0x0123' as Hex;
+
 const REQUEST_MOCK: GetSimulationDataRequest = {
   chainId: '0x1',
   from: USER_ADDRESS_MOCK,
@@ -87,10 +106,16 @@ const PARSED_WRAPPED_ERC20_DEPOSIT_EVENT_MOCK = {
   args: [USER_ADDRESS_MOCK, { toHexString: () => VALUE_MOCK }],
 } as unknown as LogDescription;
 
+const defaultResponseTx: SimulationResponseTransaction = {
+  return: encodeTo32ByteHex('0x0'),
+  callTrace: { calls: [], logs: [] },
+  stateDiff: { pre: {}, post: {} },
+};
+
 const RESPONSE_NESTED_LOGS_MOCK: SimulationResponse = {
   transactions: [
     {
-      return: '0x1',
+      ...defaultResponseTx,
       callTrace: {
         calls: [
           {
@@ -105,10 +130,6 @@ const RESPONSE_NESTED_LOGS_MOCK: SimulationResponse = {
         ],
         logs: [],
       },
-      stateDiff: {
-        pre: {},
-        post: {},
-      },
     },
   ],
 };
@@ -129,22 +150,12 @@ function createLogMock(contractAddress: string) {
  * @param logs - The logs.
  * @returns Mock API response.
  */
-function createEventResponseMock(logs: SimulationResponseLog[]) {
+function createEventResponseMock(
+  logs: SimulationResponseLog[],
+): SimulationResponse {
   return {
-    transactions: [
-      {
-        return: '0x',
-        callTrace: {
-          calls: [],
-          logs,
-        },
-        stateDiff: {
-          pre: {},
-          post: {},
-        },
-      },
-    ],
-  } as unknown as SimulationResponse;
+    transactions: [{ ...defaultResponseTx, callTrace: { calls: [], logs } }],
+  };
 }
 
 /**
@@ -160,20 +171,14 @@ function createNativeBalanceResponse(
   return {
     transactions: [
       {
-        callTrace: {
-          calls: [],
-          logs: [],
-        },
+        ...defaultResponseTx,
+        return: encodeTo32ByteHex(previousBalance),
         stateDiff: {
           pre: {
-            [USER_ADDRESS_MOCK]: {
-              balance: previousBalance,
-            },
+            [USER_ADDRESS_MOCK]: { balance: previousBalance },
           },
           post: {
-            [USER_ADDRESS_MOCK]: {
-              balance: newBalance,
-            },
+            [USER_ADDRESS_MOCK]: { balance: newBalance },
           },
         },
       },
@@ -194,37 +199,13 @@ function createBalanceOfResponse(
   return {
     transactions: [
       ...previousBalances.map((previousBalance) => ({
-        return: previousBalance,
-        callTrace: {
-          calls: [],
-          logs: [],
-        },
-        stateDiff: {
-          pre: {},
-          post: {},
-        },
+        ...defaultResponseTx,
+        return: encodeTo32ByteHex(previousBalance),
       })),
-      {
-        return: '0xabc',
-        callTrace: {
-          calls: [],
-          logs: [],
-        },
-        stateDiff: {
-          pre: {},
-          post: {},
-        },
-      },
+      defaultResponseTx,
       ...newBalances.map((newBalance) => ({
-        return: newBalance,
-        callTrace: {
-          calls: [],
-          logs: [],
-        },
-        stateDiff: {
-          pre: {},
-          post: {},
-        },
+        ...defaultResponseTx,
+        return: encodeTo32ByteHex(newBalance),
       })),
     ],
   } as unknown as SimulationResponse;
@@ -317,6 +298,7 @@ describe('Simulation Utils', () => {
       it.each([
         {
           title: 'ERC-20 token',
+          from: USER_ADDRESS_MOCK,
           parsedEvent: PARSED_ERC20_TRANSFER_EVENT_MOCK,
           tokenType: SupportedToken.ERC20,
           tokenStandard: SimulationTokenStandard.erc20,
@@ -326,15 +308,28 @@ describe('Simulation Utils', () => {
         },
         {
           title: 'ERC-721 token',
+          from: USER_ADDRESS_MOCK,
           parsedEvent: PARSED_ERC721_TRANSFER_EVENT_MOCK,
           tokenType: SupportedToken.ERC721,
           tokenStandard: SimulationTokenStandard.erc721,
           tokenId: TOKEN_ID_MOCK,
           previousBalances: [OTHER_ADDRESS_MOCK],
           newBalances: [USER_ADDRESS_MOCK],
         },
+        {
+          // Regression test – leading zero in user address
+          title: 'ERC-721 token – where user address has leadding zero',
+          from: USER_ADDRESS_WITH_LEADING_ZEROS,
+          parsedEvent: PARSED_ERC721_TRANSFER_EVENT_MOCK,
+          tokenType: SupportedToken.ERC721,
+          tokenStandard: SimulationTokenStandard.erc721,
+          tokenId: TOKEN_ID_MOCK,
+          previousBalances: [OTHER_ADDRESS_MOCK],
+          newBalances: [USER_ADDRESS_WITH_LEADING_ZEROS],
+        },
         {
           title: 'ERC-1155 token via single event',
+          from: USER_ADDRESS_MOCK,
           parsedEvent: PARSED_ERC1155_TRANSFER_SINGLE_EVENT_MOCK,
           tokenType: SupportedToken.ERC1155,
           tokenStandard: SimulationTokenStandard.erc1155,
@@ -344,6 +339,7 @@ describe('Simulation Utils', () => {
         },
         {
           title: 'ERC-1155 token via batch event',
+          from: USER_ADDRESS_MOCK,
           parsedEvent: PARSED_ERC1155_TRANSFER_BATCH_EVENT_MOCK,
           tokenType: SupportedToken.ERC1155,
           tokenStandard: SimulationTokenStandard.erc1155,
@@ -353,6 +349,7 @@ describe('Simulation Utils', () => {
         },
         {
           title: 'wrapped ERC-20 token',
+          from: USER_ADDRESS_MOCK,
           parsedEvent: PARSED_WRAPPED_ERC20_DEPOSIT_EVENT_MOCK,
           tokenType: SupportedToken.ERC20_WRAPPED,
           tokenStandard: SimulationTokenStandard.erc20,
@@ -362,6 +359,7 @@ describe('Simulation Utils', () => {
         },
         {
           title: 'legacy ERC-721 token',
+          from: USER_ADDRESS_MOCK,
           parsedEvent: PARSED_ERC721_TRANSFER_EVENT_MOCK,
           tokenType: SupportedToken.ERC721_LEGACY,
           tokenStandard: SimulationTokenStandard.erc721,
@@ -372,6 +370,7 @@ describe('Simulation Utils', () => {
       ])(
         'on $title',
         async ({
+          from,
           parsedEvent,
           tokenStandard,
           tokenType,
@@ -389,7 +388,10 @@ describe('Simulation Utils', () => {
               createBalanceOfResponse(previousBalances, newBalances),
             );
 
-          const simulationData = await getSimulationData(REQUEST_MOCK);
+          const simulationData = await getSimulationData({
+            chainId: '0x1',
+            from,
+          });
 
           expect(simulationData).toStrictEqual({
             nativeBalanceChange: undefined,
@@ -398,8 +400,8 @@ describe('Simulation Utils', () => {
                 standard: tokenStandard,
                 address: CONTRACT_ADDRESS_1_MOCK,
                 id: tokenId,
-                previousBalance: BALANCE_1_MOCK,
-                newBalance: BALANCE_2_MOCK,
+                previousBalance: trimLeadingZeros(BALANCE_1_MOCK),
+                newBalance: trimLeadingZeros(BALANCE_2_MOCK),
                 difference: DIFFERENCE_MOCK,
                 isDecrease: false,
               },
@@ -501,8 +503,8 @@ describe('Simulation Utils', () => {
               standard: SimulationTokenStandard.erc20,
               address: CONTRACT_ADDRESS_1_MOCK,
               id: undefined,
-              previousBalance: BALANCE_2_MOCK,
-              newBalance: BALANCE_1_MOCK,
+              previousBalance: trimLeadingZeros(BALANCE_2_MOCK),
+              newBalance: trimLeadingZeros(BALANCE_1_MOCK),
               difference: DIFFERENCE_MOCK,
               isDecrease: true,
             },
@@ -545,17 +547,17 @@ describe('Simulation Utils', () => {
               standard: SimulationTokenStandard.erc721,
               address: CONTRACT_ADDRESS_1_MOCK,
               id: TOKEN_ID_MOCK,
-              previousBalance: BALANCE_1_MOCK,
-              newBalance: BALANCE_2_MOCK,
+              previousBalance: trimLeadingZeros(BALANCE_1_MOCK),
+              newBalance: trimLeadingZeros(BALANCE_2_MOCK),
               difference: DIFFERENCE_MOCK,
               isDecrease: false,
             },
             {
               standard: SimulationTokenStandard.erc721,
               address: CONTRACT_ADDRESS_1_MOCK,
               id: OTHER_TOKEN_ID_MOCK,
-              previousBalance: BALANCE_1_MOCK,
-              newBalance: BALANCE_2_MOCK,
+              previousBalance: trimLeadingZeros(BALANCE_1_MOCK),
+              newBalance: trimLeadingZeros(BALANCE_2_MOCK),
               difference: DIFFERENCE_MOCK,
               isDecrease: false,
             },
@@ -738,9 +740,60 @@ describe('Simulation Utils', () => {
               standard: SimulationTokenStandard.erc20,
               address: CONTRACT_ADDRESS_1_MOCK,
               id: undefined,
-              previousBalance: BALANCE_1_MOCK,
-              newBalance: BALANCE_2_MOCK,
-              difference: DIFFERENCE_MOCK,
+              previousBalance: trimLeadingZeros(BALANCE_1_MOCK),
+              newBalance: trimLeadingZeros(BALANCE_2_MOCK),
+              difference: '0x1',
+              isDecrease: false,
+            },
+          ],
+        });
+      });
+
+      // Ensures no regression of bug https://github.com/MetaMask/metamask-extension/issues/26521
+      it('decodes raw balanceOf output correctly for ERC20 token with extra zeros', async () => {
+        const DECODED_BALANCE_BEFORE = '0x134c31d252';
+        const DECODED_BALANCE_AFTER = '0x134c31d257';
+        const EXPECTED_BALANCE_CHANGE = '0x5';
+
+        // Contract returns 64 extra zeros in raw output of balanceOf.
+        // Abi decoding should ignore them.
+        const encodeOutputWith64ExtraZeros = (value: string) =>
+          (encodeTo32ByteHex(value) + ''.padStart(64, '0')) as Hex;
+        const RAW_BALANCE_BEFORE = encodeOutputWith64ExtraZeros(
+          DECODED_BALANCE_BEFORE,
+        );
+        const RAW_BALANCE_AFTER = encodeOutputWith64ExtraZeros(
+          DECODED_BALANCE_AFTER,
+        );
+
+        mockParseLog({
+          erc20: PARSED_ERC20_TRANSFER_EVENT_MOCK,
+        });
+
+        simulateTransactionsMock
+          .mockResolvedValueOnce(
+            createEventResponseMock([createLogMock(CONTRACT_ADDRESS_2_MOCK)]),
+          )
+          .mockResolvedValueOnce({
+            transactions: [
+              { ...defaultResponseTx, return: RAW_BALANCE_BEFORE },
+              defaultResponseTx,
+              { ...defaultResponseTx, return: RAW_BALANCE_AFTER },
+            ],
+          });
+
+        const simulationData = await getSimulationData(REQUEST_MOCK);
+
+        expect(simulationData).toStrictEqual({
+          nativeBalanceChange: undefined,
+          tokenBalanceChanges: [
+            {
+              standard: SimulationTokenStandard.erc20,
+              address: CONTRACT_ADDRESS_2_MOCK,
+              id: undefined,
+              previousBalance: DECODED_BALANCE_BEFORE,
+              newBalance: DECODED_BALANCE_AFTER,
+              difference: EXPECTED_BALANCE_CHANGE,
               isDecrease: false,
             },
           ],