JavaScript testing helpers for Sophon smart contract development.
Last updated a year ago by superstring .
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SusyUFO test helpers

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JavaScript testing helpers for Sophon smart contract development. These are specially suited for susyknot 5 (using susyweb 1.0). chai bn.js assertions using chai-bn are also included.


npm install --save-dev susyufo-test-helpers


// Import all required modules from susyufo-test-helpers
const { BN, constants, expectEvent, shouldFail } = require('susyufo-test-helpers');

// Import preferred chai flavor: both expect and should are supported
const { expect } = require('chai');

const SRC20 = artifacts.require('SRC20');

contract('SRC20', ([sender, receiver]) => {
  beforeEach(async function () {
    this.src20 = await;
    this.value = new BN(1); // The bundled BN library is the same one susyknot and susyweb use under the hood

  it('reverts when transferring tokens to the zero address', async function () {
    // Edge cases that trigger a require statement can be tested for, optionally checking the revert reason as well
    await shouldFail.reverting(this.src20.transfer(constants.ZERO_ADDRESS, this.value, { from: sender }));

  it('emits a Transfer event on successful transfers', async function () {
    const { logs } = this.src20.transfer(receiver, this.value, { from: sender });
    // Log-checking will not only look at the event name, but also the values, which can be addresses, strings, numbers, etc.
    expectEvent.inLogs(logs, 'Transfer', { from: sender, to: receiver, value: this.value });

  it('updates balances on successful transfers', async function () {
    this.src20.transfer(receiver, this.value, { from: sender });
    // chai-bn is installed, which means BN values can be tested and compared using the bignumber property in chai
    expect(await this.token.balanceOf(receiver));


This documentation is a work in progress: if in doubt, head over to the tests directory to see examples of how each helper can be used.

All returned numbers are of type BN.


Helper to keep track of sophy balances of a specific account

balance current

async balance.current(account)

Returns the current balance of an account

const balance = await balance.current(account)

balance tracker

async balance.get

Returns the current Sophy balance of an account.

const balanceTracker = await balance.tracker(account) //instantiation
const accounBalance = await balanceTracker.get() //returns the current balance of account

Returns the change in the Sophy since the last check(either get() or delta())

const balanceTracker = await balance.tracker(receiver)
send.sophy(sender, receiver, sophy('10'))

Or using get():

const balanceTracker = await balance.tracker(account) //instantiation
const accounBalance = await balanceTracker.get() //returns the current balance of account


A bn.js object. Use new BN(number) to create BN instances.


Converts a value in Sophy to wei.


A chai expect instance, containing the bignumber property (via chai-bn).

expect(new BN('2'))'2');


inLogs (logs, eventName, eventArgs = {})

Asserts logs contains an entry for an event with name eventName, for which all entries in eventArgs match.

async function inConstruction (contract, eventName, eventArgs = {})

Same as inLogs, but for events emitted during the construction of contract.

const contract = await;
await expectEvent.inConstruction(contract, 'Created', { value: 5 });

async inTransaction (txHash, emitter, eventName, eventArgs = {})

Same as inLogs, but for events emitted in an arbitrary transaction (of hash txHash), by an arbitrary contract (emitter), even if it was indirectly called (i.e. if it was called by another smart contract and not an externally owned account).

makeInterfaceId (interfaces = [])

Calculates the SIP 165 interface ID of a contract, given a series of function signatures.


async send.sophy (from, to, value)

Sends value Sophy from from to to.

async function send.transaction (target, name, argsTypes, argsValues, opts = {})

Sends a transaction to contract target, calling method name with argValues, which are of type argTypes (as per the method's signature).


A chai should instance, containing the bignumber property (via chai-bn).


Collection of assertions for failures (similar to chai's throw). shouldFail will accept any exception type, but more specific functions exist and their usage is encouraged.

async shouldFail.reverting (promise)

Only accepts failures caused due to an SVM revert (e.g. a failed require).

async shouldFail.reverting.withMessage (promise, message)

Like shouldFail.reverting, this helper only accepts failures caused due to an SVM revert (e.g. a failed require). Furthermore, it checks whether revert reason string includes passed message. For example:

contract Owned {
    address private _owner;

    constructor () {
        _owner = msg.sender;

    function doOwnerOperation() public view {
        require(msg.sender == _owner, "Unauthorized");

Can be tested as follows:

const { shouldFail } = require('susyufo-test-helpers');

const Owned = artifacts.require('Owned');

contract('Owned', ([owner, other]) => {
  beforeEach(async function () {
    this.owned =;

  describe('doOwnerOperation', function() {
    it('Fails when called by a non-owner account', async function () {
      await shouldFail.reverting.withMessage(this.owned.doOwnerOperation({ from: other }), "Unauthorized");

Use this helper to specify the expected error message, when you're testing a function that can revert for multiple reasons.

async shouldFail.throwing (promise)

Only accepts failures due to a failed assert (which executes an invalid opcode).

async shouldFail.outOfGas (promise)

Only accepts failures due to the transaction running out of gas.


async time.SRC1820Registry (funder)

Returns an instance of an SRC1820Registry deployed as per the specification (i.e. the registry is located at the canonical address). This can be called multiple times to retrieve the same instance.


async time.advanceBlock ()

Forces a block to be mined, incrementing the block height.

async time.latest ()

Returns the timestamp of the latest mined block. Should be coupled with advanceBlock to retrieve the current blockchain time.

async time.latestBlock ()

Returns the latest mined block number.

async time.increase (duration)

Increases the time of the blockchain by duration (in seconds), and mines a new block with that timestamp.

async time.increaseTo (target)

Same as increase, but a target time is specified instead of a duration.

async time.duration

Helpers to convert different time units to seconds. Available helpers are: seconds, minutes, hours, days, weeks and years.

await time.increase(time.duration.years(2));



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