fix(sdk-coin-avaxp): stake output cannot be 0

throw error if change output is 0 for permissionless validator tx

CR-1073

TICKET: CR-1073

Author: noel-bitgo

modules/sdk-coin-avaxp/src/lib/permissionlessValidatorTxBuilder.ts

@@ -476,10 +476,16 @@ export class PermissionlessValidatorTxBuilder extends TransactionBuilder {
         stakeOutputs.push(stakeOutput);
 
         if (currentTotal >= totalTarget) {
+          const changeOutputAmount = currentTotal - totalTarget;
+          if (changeOutputAmount <= 0) {
+            throw new BuildTransactionError(
+              'Change output amount must be greater than 0. Stake less or more to avoid 0 amount in utxo output.'
+            );
+          }
           const changeOutput = new avaxSerial.TransferableOutput(
             assetId,
             new TransferOutput(
-              new BigIntPr(currentTotal - totalTarget),
+              new BigIntPr(changeOutputAmount),
               new OutputOwners(
                 new BigIntPr(this.transaction._locktime),
                 new Int(this.transaction._threshold),

modules/sdk-coin-avaxp/test/resources/avaxp.ts

@@ -614,6 +614,7 @@ export const BUILD_AND_SIGN_ADD_PERMISSIONLESS_VALIDATOR_SAMPLE = {
   startTime: '1656423398',
   endTime: '1659053398',
   stakeAmount: '2370000000',
+  stakeAmountNoOutput: '4097000000',
   delegationFeeRate: 10,
   nodeId: 'NodeID-2hMqBQdjZMWdHvYu7ZPLA2CmrAdbTvpGf',
   blsPublicKey: '0xad9e9476b701edec88e53b1c314456053b3cf846a1192117872e41455f440c074d6ee89530d45e88f79ac0eda06f2887',

modules/sdk-coin-avaxp/test/resources/errors.ts

@@ -27,6 +27,8 @@ export const ERROR_CHAIN_ID_LENGTH = 'Chain id are 32 byte size';
 export const ERROR_KEY_CANNOT_SIGN = 'Private key cannot sign the transaction';
 
 export const ERROR_AMOUNT = 'Amount must be greater than 0';
+export const ERROR_CHANGE_AMOUNT =
+  'Change output amount must be greater than 0. Stake less or more to avoid 0 amount in utxo output.';
 
 export const ERROR_NONCE = 'Nonce must be greater or equal than 0';
 

modules/sdk-coin-avaxp/test/unit/lib/permissionlessValidatorTxBuilder.ts

@@ -8,6 +8,7 @@ import * as AvaxpLib from '../../../src/lib';
 import { TransactionBuilderFactory } from '../../../src/lib';
 import { PermissionlessValidatorTxBuilder } from '../../../src/lib/permissionlessValidatorTxBuilder';
 import * as testData from '../../resources/avaxp';
+import { ERROR_CHANGE_AMOUNT } from '../../resources/errors';
 // import { pvm } from '@bitgo/avalanchejs';
 
 describe('AvaxP permissionlessValidatorTxBuilder', () => {
@@ -298,4 +299,27 @@ describe('AvaxP permissionlessValidatorTxBuilder', () => {
       console.log(fullSignedTx.toJson());
     });
   });
+  it('Should fail to build if utxos change output 0', async () => {
+    const unixNow = BigInt(Math.round(new Date().getTime() / 1000));
+    const startTime = unixNow + BigInt(60);
+    const endTime = startTime + BigInt(60 * 60 * 24 + 600);
+
+    const txBuilder = new AvaxpLib.TransactionBuilderFactory(coins.get('tavaxp'))
+      .getPermissionlessValidatorTxBuilder()
+      .threshold(testData.BUILD_AND_SIGN_ADD_PERMISSIONLESS_VALIDATOR_SAMPLE.threshold)
+      .locktime(testData.BUILD_AND_SIGN_ADD_PERMISSIONLESS_VALIDATOR_SAMPLE.locktime)
+      .recoverMode(false)
+      .fromPubKey(testData.BUILD_AND_SIGN_ADD_PERMISSIONLESS_VALIDATOR_SAMPLE.bitgoAddresses)
+      .startTime(startTime.toString())
+      .endTime(endTime.toString())
+      .stakeAmount(testData.BUILD_AND_SIGN_ADD_PERMISSIONLESS_VALIDATOR_SAMPLE.stakeAmountNoOutput)
+      .delegationFeeRate(testData.BUILD_AND_SIGN_ADD_PERMISSIONLESS_VALIDATOR_SAMPLE.delegationFeeRate)
+      .nodeID(testData.BUILD_AND_SIGN_ADD_PERMISSIONLESS_VALIDATOR_SAMPLE.nodeId)
+      .blsPublicKey(testData.BUILD_AND_SIGN_ADD_PERMISSIONLESS_VALIDATOR_SAMPLE.blsPublicKey)
+      .blsSignature(testData.BUILD_AND_SIGN_ADD_PERMISSIONLESS_VALIDATOR_SAMPLE.blsSignature)
+      .utxos(testData.BUILD_AND_SIGN_ADD_PERMISSIONLESS_VALIDATOR_SAMPLE.utxos);
+    await txBuilder.build().catch((error) => {
+      assert(error.message === ERROR_CHANGE_AMOUNT);
+    });
+  });
 });