To developers, writing test case is a important skill that everyone have to learn and expert. Because you can not code the perfect software, when you can not cover all the case. In Node.js project, it’s neccessary to use testing framework such as Ava, Jest, Jasmine, Karma, … The testing framework will boost your performance and make your life easier.

Today, I will completely show you how to use Ava testing framework.

Table of Contents

Installing Ava


npm install ava --save-dev

Use test() function in Ava

In order to use test() function in ava, you can use two ways to get test() function;

import test from 'ava'  // ES6 syntax


const test = require('ava');

test() function have the parameters that include title - string type, and asynchronous function.

Title must be unique within each test file. The asynchronous function will be called when your test is run. It’s passed an execution object as its first argument.


test('name_action', async t => {
  // prepare data for testing
  // ...

  try {
    // implement test case at here 
    // ... 
    // t.deepEqual(...);
    // t.pass();
  } catch (e) {
    // process when having exceptions
    // ... 
    // console.log(e);
  } finally {
    // process something when ending test case 
    // ...

Note: In order for the enhanced assertion messages to behave correctly, the first arguments must be named t.

Running test serially

By default, tests run concurrently. But when each test case works with I/O operations, it can cause the error. So, you want your test cases that must be run synchronously.

Use .serial modifier, it will force those tests to run serially before the concurrent ones.

Note: In your one test file, you use each test case with .serial’, then test cases will run serially. But when you want to run many test files, all of test files will run concurrently if you do not set the flag *–serial.

ava --serial .\\test_folder\\*.js

Using async keyword

Ava supports asyn function in the second parameter.

test('action', async t => {
  // do something 

Running specific test

If you only want to run some test cases, not all of test cases. You can use .only modifier.

test.only('action', t => {
  // do something

Note: You can use the .only modifier with all tests. It cannot be used with hooks or .todo().

Skipping test

When your test case can not be fixed, you can use the .skip modifier to skip this test case.

test.skip('action', t => {
  // do something

Using assertion

The below is the common assertion that you will need to use.

  • .pass([message]): passing assertion.
  • .fail([message]): failing assertion.
  • .is(value, expected, [message]): assert that value is equal to expected.
  • .deepEqual(value, expected, [message]): assert that value is equal to expected.

Use before and after hooks

  • test.before() : register a hook to be run before the first test in your test file.
  • test.after() : register a hook to be run after the last test.
  • test.after.always() : register a hook that will always run once your tests ans other hooks complete.
  • test.beforeEach() : register a hook to be run before each test in your test file.
  • test.afterEach() : register a hook to be run after each test.
  • test.afterEach.always() : register an after hook that is called even if other test hooks, or the test itself, fail.
  • .before() hooks execute before .beforeEach() hooks.
  • .afterEach() hooks before .after() hooks.

Wrapping up

  • Tests run concurrently.
  • Each test file is run in a seperate Node.js process. It’s greate performance on modern multi-core processors, allowing multiple test files to execute in parallel.

Thanks for your reading.


The comparison between ava and jest

Ava testing framework documentation

Assertions in Ava

Configuration in Ava

Execution Context in Ava