I had written a library of small Javascript functions that I wanted to do cover with some basic tests. However, I found it really hard to find any information about how to do this.
When I searched, I was barraged by so much information that everything very quickly seemed to get overly complicated, and led me further and further away from just simple plain Javascript testing. I really didn’t want to get involved with Javascript runtime environments like Node.js just yet, but I felt that a lot of the resources I was finding were targeting it.
I liked the sound of tape because it seemed like it was a fairly minimal stand-alone test suite, but for some reason I didn’t really get far with it.
Not having much success with rolling my own unit tests, I decided to see what unit testing frameworks were on offer.
I remembered that AWS CodeStar has sample software projects, and these come with tests and suggested test frameworks, so I decided to see what they were using.
Unfortunately, there were no vanilla Javascript sample projects offered, every web application using Javascript used Node.js. So I just decided to give in.
I could see that the build files for the Node.js project used the following tools:
I don’t know why they use 2 unit testing frameworks, so maybe there was a difference between them. Here is how unitjs.com describes them both:
“Unit.js is an assertion library for Javascript, running on Node.js and the browser. It works with any test runner and unit testing framework like Mocha, Jasmine, Karma, protractor (E2E test framework for Angular apps), QUnit, … and more.”
“Mocha is a feature-rich JavaScript test framework running on Node.js and in the browser, making asynchronous testing simple and fun. Mocha tests run serially, allowing for flexible and accurate reporting, while mapping uncaught exceptions to the correct test cases.”
This also meant that I would potentially need to learn 3 different tools in order to try and achieve the simple objective of testing my existing vanilla Javascript.
Total overkill!
Anyway, I decided to stop moaning and start.
I have written my own Javascript library with some common functions that I use frequently. I picked a simple function which I wanted to write a test for:
lib_javascript.js:
function isXML(str) {
var XML_HEADER="<?xml version=";
if (str.includes(XML_HEADER)) {
return true;
}
return false;
}
According to the documentation, to test this function using Unit.js and Mocha, my test case should look like this:
. ./tests/test.js
'use strict';
var test = require('unit.js');
var lib = require('../lib_javascript.js');
describe('Tests index', function() {
it('tests if a string is XML', function() {
var rst = lib.isXML("");
test.bool(rst).isFalse();
});
});
And then to run the test, I should define my test frameworks in a file:
.package.json:
{
"name": "library",
"description": "Javascript library",
"version": "0.0.1",
"private": true,
"devDependencies": {
"mocha": "5.0.0",
"unit.js": "2.0.0"
},
"scripts": {
"test": "mocha --recursive tests"
}
}
And then install and run the tests:
$ npm install
$ npm test
Which gave this output:
> mocha --recursive tests
Tests index
✓ tests if a string is XML
1 passing (10ms)