fix(sdk-coin-stx): remove array iteration from verifyTransaction

Replace the map() loops over recipients and outputs — and lodash isEqual —
with direct index-0 access. STX enforces single-recipient at the top of
the method, so iterating an array of one was misleading. Compare the
single recipient address, amount, and memo directly against the single
decoded output.

Ticket: CSHLD-839
Session-Id: 7de30368-fc1b-4b09-9d2e-55be78e462dc
Task-Id: 2203e736-35f2-4e2f-8cde-6cdbd0d3e2b6

Author: prajwalu142

modules/sdk-coin-stx/src/stx.ts

@@ -1,4 +1,3 @@
-import _ from 'lodash';
 import {
   AuditDecryptedKeyParams,
   BaseCoin,
@@ -116,39 +115,27 @@ export class Stx extends BaseCoin {
       throw new Error('missing required tx prebuild property txHex');
     }
     const explainedTx = await this.explainTransaction({ txHex: rawTx, feeInfo: { fee: '' } });
-    if (txParams.recipients !== undefined && explainedTx) {
-      const filteredRecipients = txParams.recipients.map((recipient) => {
-        const addressDetails = getMemoIdAndBaseAddressFromAddress(recipient.address);
-        return {
-          address: addressDetails.address,
-          amount: BigInt(recipient.amount),
-        };
-      });
-      const filteredOutputs = explainedTx.outputs.map((output) => ({
-        address: output.address,
-        amount: BigInt(output.amount),
-      }));
-      if (!_.isEqual(filteredOutputs, filteredRecipients)) {
+    const recipient = txParams.recipients?.[0];
+    if (recipient !== undefined && explainedTx) {
+      const txOutput = explainedTx.outputs[0];
+      const recipientAddress = getMemoIdAndBaseAddressFromAddress(recipient.address).address;
+      if (txOutput?.address !== recipientAddress || BigInt(txOutput?.amount) !== BigInt(recipient.amount)) {
         throw new Error('Tx outputs does not match with expected txParams recipients');
       }
       // compare memo
       let memoInput = '';
-      let memoOutput = '';
       if (memo && memo.value) {
         memoInput = memo.value;
-      } else if (txParams.recipients.length) {
-        const addressDetails = getMemoIdAndBaseAddressFromAddress(txParams.recipients[0].address);
-        memoInput = addressDetails.memoId ? addressDetails.memoId : '';
-      }
-      if (explainedTx.memo) {
-        memoOutput = explainedTx.memo;
+      } else {
+        const addressDetails = getMemoIdAndBaseAddressFromAddress(recipient.address);
+        memoInput = addressDetails.memoId ?? '';
       }
-      if (!_.isEqual(memoInput, memoOutput)) {
+      const memoOutput = explainedTx.memo ?? '';
+      if (memoInput !== memoOutput) {
         throw new Error('Tx memo does not match with expected txParams recipient memo');
       }
-      // compare send amount — STX supports only one recipient, validated above
-      const recipientAmount = txParams.recipients.length ? new BigNumber(txParams.recipients[0].amount) : new BigNumber(0);
-      if (!recipientAmount.isEqualTo(explainedTx.outputAmount)) {
+      // compare amount
+      if (!new BigNumber(recipient.amount).isEqualTo(explainedTx.outputAmount)) {
         throw new Error('Tx total amount does not match with expected total amount field');
       }
     }

modules/sdk-coin-stx/test/unit/stx.ts

@@ -373,23 +373,6 @@ describe('STX:', function () {
       result.should.equal(true);
     });
 
-    it('should succeed to verify when memo is passed inside recipient address', async function () {
-      const wallet = new Wallet(bitgo, basecoin, {});
-      const txParams = {
-        recipients: [
-          {
-            address: `${testData.txExplainedTransfer.recipient}?memoId=${encodeURIComponent(
-              testData.txExplainedTransfer.memo
-            )}`,
-            amount: testData.txExplainedTransfer.outputAmount,
-          },
-        ],
-        wallet,
-      };
-      const result = await basecoin.verifyTransaction({ txPrebuild, txParams });
-      result.should.equal(true);
-    });
-
     it('should fail to verify transaction with wrong recipient address', async function () {
       const wallet = new Wallet(bitgo, basecoin, {});
       const txParams = {