Jest test is not passing through any parameters (becomes 'undefined')

Question

EDIT: The variable username becomes undefined for some reason. I tried passing other variables too, but none of them appear as they should with console.log() .

I have a jest file ("index.test.js") for testing my API:

'use strict';

const request = require('supertest');
const app = require('./index');

describe('Test login', () => {
  test('POST /login', () => {
        return request(app)
             .post('/login')
             .send({username: 'preset1'})  //suggestion by @acincognito
             .expect(301)

    });

});

and a corresponding POST route in my nodejs file ("index.js") :

...

function contains(arr, key, val) {
    for (var i = 0; i < arr.length; i++) {
        if(arr[i][key] === val) {
            return true
        }; 
    }
    return false;
}

app.post("/login", async (req, res) => {
    try {
      var username = req.body.username;
      const data = await readFile("results.json");
      var json = JSON.parse(data);
      if (contains(json, "name", username) === true){

         ...

         return res.redirect(301,"/");
       } else {
         return res.redirect(401,"/");
       }
    } catch (error) {
        return res.redirect("/");
    }
});

JSON file ("results.json") has the following format:

[
  {"name":"preset1","otherstuff":[]},
  ...
  {"name":"preset5","otherstuff":[]}
]

I am getting the error message:

expected 301 "Moved Permanently", got 401 "Unauthorized"

NOTE: When I run the code manually on a local server, everything works as it should which seems to contradict the output of the test.

Answer 1

Add a console.log(json) to your app.post function to see what gets parsed.

After looking at the docs for supertest : apparently .set('username','preset1') is for setting headers in your request, but according to your app.post username is inside the request's body, therefore try .send({username: 'preset1'}) .

Answer 2

I needed to encode a Javascript Object into a string.

function serialize(obj){
    return Object.keys(obj).map(k => `${encodeURIComponent(k)}=${encodeURIComponent(obj[k])}`).join('&');
}

// Code from : https://stackoverflow.com/questions/1714786/query-string-encoding-of-a-javascript-object

Instead of:

.send({username: 'preset1'})

Replace with:

.send(serialize({username: 'preset1'}))

Edit: This did not work for all parameters.