How do you Mocha test if else statements? - node.js

Question

I am having trouble trying to write a Mocha test for an if else statement in Node.js. Here is what is being tested:
exports.restrict = function(req, res, next) {
if (req.session.user) {
next();
} else {
req.session.error = 'Access denied!';
res.redirect('/login');
}
}
This is how I am trying to test it:
describe('interface', function(){
it('should show ability to asynchronously deny a user with an incorrect password', function(done){
function restrict (req, res, next){
if (req.session.user) {
next();
done();
} else {
req.session.error.should.equals('Access denied');
req.redirect.should.equals('/login');
done();
}
}
});
});
The error I receive when running the test is that it say timeout because it exceeds 2000ms. What am I doing wrong?

Answer 1

In your test you define a restrict function which is never called, so done is never called and the test times out. This is what you are doing wrong. There's nothing special to using if... else in Mocha tests.
Wider issue: what you show in your question suggests that you duplicate the code of your module into your test suite. That's a terrible way to go about testing code. You should structure your module so that your test suite is able to exercise its functions without duplication of code.

Answer 2

Yes, there was a incorrect statement in your test file. Reading your source file, we have two scenarios to check for restrict function.
if user session exist, check if next() is called
if user session not exist, check if redirect() is called and req.session.error is assigned
Based on top bullets, we can design our test such as
const sinon = require('sinon');
const chai = require('chai');
const assert = chai.assert;
const src = require('./src');
describe('interface', function () {
it('calls next() if user session exist', function () {
const next = sinon.spy();
const res = sinon.spy();
const req = {
session: {
user: 'username' // set user session
}
}
src.restrict(req, res, next);
assert(next.called);
});
it('redirects if user session not exist', function () {
const next = sinon.spy();
const res = {
redirect: sinon.spy()
}
const req = {
session: {}
}
src.restrict(req, res, next);
assert.equal(req.session.error, 'Access denied!');
assert(res.redirect.calledWith('/login'));
assert.isFalse(next.called)
});
});
we don't need to use done() because restrict() is not async function.
We also use sinon here to spy req, res and next variable.
Ref:
- https://sinonjs.org/
Hope it helps.