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How to Simulate a Function Call

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


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 } from '@aztec/aztec.js';
Source code: yarn-project/end-to-end/src/composed/docs_examples.test.ts#L5-L7

Define contract

Get a previously deployed contract like this:

const contract = await, TokenContractArtifact, wallet);
Source code: yarn-project/end-to-end/src/composed/docs_examples.test.ts#L38-L40

Simulating function calls

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

const balance = await contract.methods.balance_of_public(wallet.getAddress()).simulate();
Source code: yarn-project/end-to-end/src/composed/docs_examples.test.ts#L46-L49
  • If the simulated function is unconstrained you will get a properly typed value.
  • If the simulated function is public or private it will return a Field array of size 4.