Test nodejs methode with Mocha and chai libraries - node.js

Question

I want to test this methode below with Mocha and chai, but I got an error :
I want to test this methode below with Mocha and chai, but I got an error :
exports.getCaracteristiques = (req,res) => {
db.query('SELECT "titi", "toto"')
.then( ({rows}) => {
var caracteristiqueResult = rows.map((row) => {
return {
'idCaracteristique': row.CARACT_ID
, 'libelleCaracteristique': row.toto
, 'libelleCaracteristique': row.titi
};
})
res.json(caracteristiqueResult);
})
.catch(err => {
// handle the error
console.log("ERROR :", err)
res.status(500).end(err)
})
};
test.js file contains :
var expect = require('chai').expect;
require("../config/config");
var ctr = require('../api/controllers/caracteristiques')
describe('Caracteristiques', () => {
it('returns an array of Carateristiques', () => {
// This will fail if "Caracteristiques result "is
// not array.
return ctr.getCaracteristiques.then(function(data){
expect(data).to.be.a('array');
});// no catch, it'll figure it out since the promise is rejected
});
})
but I got this error :
Caracteristiques
1) returns an array of Carateristiques
0 passing (0ms)
1 failing
1) Caracteristiques
returns an array of Carateristiques:
TypeError: ctr.getCaracteristiques.then is not a function
at Context.it (test\caracteristiques.js:13:40)
How to resolve this problem ?

Answer 1

The error:
TypeError: ctr.getCaracteristiques.then is not a function
Is just plain right. You missed the () when onvoking the getCaracteristiques() method.
This should work:
return ctr.getCaracteristiques().then(function(data){
expect(data).to.be.a('array');
});
Edit after OP comment:
In your code, getCaracteristiques requires a req and a res objects. My guess is that your using express or any other node js http library, which usually fills that for you.
In mocha, we are calling the method by ourselves, without any web server, so we need to craft those objects by ourselves.
The getCaracteristiques method does not use req, but it does needs resto have a json() method. So we can do:
const res = {
json: (a) => a,
};
return ctr.getCaracteristiques({}, res).then(function(data){
expect(data).to.be.a('array');
});
In our test so getCaracteristiques return what we want (just the data, because the fake jsonmethod just yields away its parameter).
Now, the test will fail again, because getCaracteristiques does not return the jsoncall. If we add a return statement, the whole thing should work:
exports.getCaracteristiques = (req,res) => {
return db.query('SELECT "CARACT_ID", "CARACT_LIB", "COULEUR", "IMAGE_ACTIVE",
"IMAGE_PASSIVE", "ACTIF" FROM "DIM_PRC_CARACT"')
.then( ({rows}) => {
var caracteristiqueResult = rows.map((row) => {
return {
'idCaracteristique': row.CARACT_ID
, 'libelleCaracteristique': row.CARACT_CD
, 'libelleCaracteristique': row.CARACT_LIB
, 'couleurCaracteristique': row.COULEUR
, 'pictogrammeActifCaracteristique': row.IMAGE_PASSIVE
, 'pictogrammePassifCaracteristique': row.IMAGE_PASSIVE
};
})
return res.json(caracteristiqueResult);
})
Note that a return was added to db.query and res.json, so the getCaracteristiques method now returns a promise of the caracteristiques.