How to Simulate a Function Call

This guide explains how to simulate a function call using Aztec.js.

Prerequisites

You should have a wallet to act as the caller, and a contract that has been deployed.

You can learn how to create wallets from this guide.

You can learn how to deploy a contract here.

Relevant imports

You will need to import this from Aztec.js:

import_contract

import { Contract } from '@aztec/aztec.js';

^{_{Source code: yarn-project/end-to-end/src/composed/docs_examples.test.ts#L7-L9}}

Define contract

Get a previously deployed contract like this:

get_contract

const contract = await Contract.at(deployedContract.address, TokenContractArtifact, wallet);

^{_{Source code: yarn-project/end-to-end/src/composed/docs_examples.test.ts#L45-L47}}

Simulating function calls

Call the simulate function on the typescript contract wrapper like this:

simulate_function

const balance = await contract.methods.balance_of_public(newWallet.getAddress()).simulate();
expect(balance).toEqual(1n);

^{_{Source code: yarn-project/end-to-end/src/composed/docs_examples.test.ts#L54-L57}}

Note

• If the simulated function is utility you will get a properly typed value.
• If the simulated function is public or private it will return a Field array of size 4.