Skip to main content

Test Scenario

Test scenarios are the current industry standard to ensure a contract has the expected behavior. Basically a test is a program that originates the contract(s), calls them and checks the storage value(s) and account(s) balances.

This article presents how to write and execute tests with Completium.

Completium JS library

Completium provides a Javascript programming library to program interactions with contracts. It benefits from the configuration of endpoints and accounts established with the CLI.

Before using $completium-cli as a programming library, install the CLI to configure endpoint and account(s).

Create test project

Follow the standard npm process to create a javascript project and install completium-cli:

$ mkdir test
$ cd test
$ npm init -y
$ npm i @completium/completium-cli


The following example illustrates how to test the State machine contract of the Archetype tutorial.

The goal is to check whether the contract is in the right state after a series of calls to init, inc_value twice and complete entrypoints, and to check whether the caller's balance is unchanged while transferring 5tz to init (within cost of transactions).

const assert     = require('assert');
const { deploy, getBalance } = require('@completium/completium-cli');

const test = async () => {
// Scenario
const balance_before = (await getBalance()).toNumber();
var cost = 0;
var [state_machine, op] = await deploy('state_machine.arl');
cost += op.cost.toNumber();
// send 5tz to contract
var op = await state_machine.init({ amount: "5tz" });
cost += op.cost.toNumber();
var op = await state_machine.inc_value();
cost += op.cost.toNumber();
var op = await state_machine.inc_value();
cost += op.cost.toNumber();
// Should return the 5tz sent with `init`
var op = await state_machine.complete();
cost += op.cost.toNumber();
// Test final state and balance
const storage = await;
const balance = (await getBalance()).toNumber();
assert(storage._state == 3, "Invalid contract state");
assert(balance == balance_before - cost, "Invalid caller balance");


The cost of transactions is accumulated in the local cost variable. It is used to test that the caller has got back the 5 tezies send to init entrypoint.

The script is using the current account and endpoint, shown with the Completium CLI commands:

$ completium-cli show endpoint
Current network: edo
Current endpoint:
$ completium-cli show account
Current account: admin
Public key hash: tz1VSUr8wwNhLAzempoch5d6hLRiTh8Cjcjb
Balance on sandbox: 9998.466387

This means the script is using the edo network with the account admin. It is possible to programmatically switch account and endpoint from within the test scenario.

Run test

Edit the package file to set the test command:

"name": "demo",
"version": "1.0.0",
"description": "",
"main": "test.js",
"scripts": {
"test": "node test.js"
"keywords": [],
"author": "",
"license": "ISC",
"dependencies": {
"@completium/completium-cli": "^0.1.8"

Launch the test with:

npm test


$completium-cli provides the possibility to run the scenario on a local sandbox network.

In order to launch the test in a sandbox, run the following script:

completium-cli start sandbox
completium-cli set endpoint http://localhost:20000
npm test
completium-cli stop sandbox