Need advice about testing using Chimp.js/Mocha in Meteor.js

I'm trying to teach myself testing with Meteor but there is so much conflicting and outdated info online it's really difficult to work out what I need to do.

My current situation it that I have an application using the latest Meteor version (and the imports folder structure).

I've installed chimp globally and have created a /tests directory.

My first test is using chimp/mocha to fill in a form and try to insert something to the database. I'm also using the xolvio/backdoor package and running chimp like so

chimp --ddp=http://localhost:3000 --mocha --path=tests

Here's my test code:

describe('Chimp Mocha', function() {
    describe( 'Create a Client', function() {

        it( 'should fill in add client form', function() {
            browser.setValue('#clientName', 'Test')
                    .setValue('#clientEmail', 'test@test.com')
                    .selectByValue('#numberTeamMembers', '25')
                    .submitForm('#createClient')
        });

        it( 'should check the collections for new client data', function() {
            let getClient = server.execute( function() {
              return Clients.findOne({ name: 'Test' });
            });

            expect( getClient.name ).to.equal( 'Test' );
        });

        after( function() {
            server.execute( function() {
              let client = Clients.findOne( { name: 'Test' } );
              if ( client ) {
                Clients.remove( client._id );
              }
            });
        });


    });
});

This is throwing an error that Clients is undefined

However, if I add

import { Clients } from '/imports/api/clients/clients.js';

I get this error Error: Cannot find module '/imports/api/clients/clients.js'

What am I doing wrong? Should I be using chimp? Any help would really be appreciated because I don't find the Meteor guide very clear about this!

Thanks