fix(wallet-service): we must return zero-balances for tokens the user…

packages/wallet-service/src/api/balances.ts

@@ -13,6 +13,7 @@ import { closeDbAndGetError, warmupMiddleware } from '@src/api/utils';
 import { getWalletBalances, walletIdProxyHandler } from '@src/commons';
 import {
   getWallet,
+  getTokenInformation,
 } from '@src/db';
 import {
   closeDbConnection,
@@ -24,6 +25,7 @@ import cors from '@middy/http-cors';
 import Joi from 'joi';
 import errorHandler from '@src/api/middlewares/errorHandler';
 import { bigIntUtils } from '@hathor/wallet-lib';
+import { WalletTokenBalance, Balance } from '@src/types';
 
 const mysql = getDbConnection();
 
@@ -74,7 +76,15 @@ export const get: APIGatewayProxyHandler = middy(walletIdProxyHandler(async (wal
     tokenIds.push(tokenId);
   }
 
-  const balances = await getWalletBalances(mysql, getUnixTimestamp(), walletId, tokenIds);
+  let balances = await getWalletBalances(mysql, getUnixTimestamp(), walletId, tokenIds);
+
+  // If a specific token was requested but wallet has no balance, return zero balance
+  if (value.token_id && balances.length === 0) {
+    const tokenInfo = await getTokenInformation(mysql, value.token_id);
+    if (tokenInfo) {
+      balances = [new WalletTokenBalance(tokenInfo, new Balance(), 0)];
+    }
+  }
 
   await closeDbConnection(mysql);
 

packages/wallet-service/tests/api.test.ts

@@ -635,6 +635,33 @@ test('GET /balances', async () => {
     lockExpires: null,
     tokenAuthorities: { unlocked: { mint: false, melt: false }, locked: { mint: false, melt: false } },
   });
+
+  // request balance for a token the wallet doesn't have - should return zero balance
+  const tokenNotOwned = { id: 'tokennotowned', name: 'NotOwnedToken', symbol: 'NOT' };
+  await addToTokenTable(mysql, [
+    { id: tokenNotOwned.id, name: tokenNotOwned.name, symbol: tokenNotOwned.symbol, transactions: 0 },
+  ]);
+  event = makeGatewayEventWithAuthorizer('my-wallet', { token_id: 'tokennotowned' });
+  result = await balancesGet(event, null, null) as APIGatewayProxyResult;
+  returnBody = JSON.parse(result.body as string);
+  expect(result.statusCode).toBe(200);
+  expect(returnBody.success).toBe(true);
+  expect(returnBody.balances).toHaveLength(1);
+  expect(returnBody.balances).toContainEqual({
+    token: tokenNotOwned,
+    transactions: 0,
+    balance: { unlocked: 0, locked: 0 },
+    lockExpires: null,
+    tokenAuthorities: { unlocked: { mint: false, melt: false }, locked: { mint: false, melt: false } },
+  });
+
+  // request balance for a token that doesn't exist - should return empty array
+  event = makeGatewayEventWithAuthorizer('my-wallet', { token_id: 'nonexistenttoken' });
+  result = await balancesGet(event, null, null) as APIGatewayProxyResult;
+  returnBody = JSON.parse(result.body as string);
+  expect(result.statusCode).toBe(200);
+  expect(returnBody.success).toBe(true);
+  expect(returnBody.balances).toHaveLength(0);
 });
 
 test('GET /txhistory', async () => {