Making a request before all tests start in Mocha - node.js

Question

I would like to test my simple API that has /groups URL.
I want to make an API request to that URL (using Axios) before all tests begin and make the response visible to all test functions.
I am trying to make the response visible but not able to make it work. I followed a similar case with filling out the DB upfront but no luck with my case.
My simple test file below:
var expect = require('chai').expect
var axios = require('axios')
var response = {};
describe('Categories', function() {
describe('Groups', function() {
before(function() {
axios.get(config.hostname + '/groups').then(function (response) {
return response;
})
});
it('returns a not empty set of results', function(done) {
expect(response).to.have.length.greaterThan(0);
done();
})
});
});
I tried also a sligh modification of before function:
before(function(done) {
axios.get(config.hostname + '/groups')
.then(function (response) {
return response;
}).then(function() {
done();
})
});
but no luck too.
The error I am getting is simply that response isn't changing nor is visible within it. AssertionError: expected {} to have property 'length'
Summarising: How can I pass response from axios inside to in()?

Answer 1

Your first form is incorrect, because you're not returning the chained promise. As such, mocha has no way of knowing when your before is finished, or even that it's async at all. Your second form will solve this problem, but since axios.get already returns a promise, it's kind of a waste not to use mocha's built-in promise support.
As for making the response visible in the it, you need to assign it to a variable in a scope that will be visible within the it.
var expect = require('chai').expect
var axios = require('axios')
var response;
describe('Categories', function() {
describe('Groups', function() {
before(function() {
// Note that I'm returning the chained promise here, as discussed.
return axios.get(config.hostname + '/groups').then(function (res) {
// Here's the assignment you need.
response = res;
})
});
// This test does not need the `done` because it is not asynchronous.
// It will not run until the promise returned in `before` resolves.
it('returns a not empty set of results', function() {
expect(response).to.have.length.greaterThan(0);
})
});
});