https://runkit.com/58cbf7e39f7fae001762daab/58cbf7e39f7fae001762daac Related to issue https://github.com/hapijs/lab/issues/692#issuecomment-287349205

.gitignore

!*
*.swp
node_modules

index.js

'use strict';

var Lab = require("lab");
var Code = require("code");

// Test shortcuts
const lab = exports.lab = Lab.script();
const describe = lab.experiment;
const it = lab.test;
const expect = Code.expect;


const base = JSON.stringify({user:{name:'John',surname:'Doe'}});
let mutable;
let mutatorApi;

const randomPromise = (fn) => new Promise((res,rej)=>{
    
   const randomTime = Math.round(Math.random() * 10000) % 2000;
   console.log('Random time is %d',randomTime);
   setTimeout(() => {
       
       fn();
       res();
   }, 
   randomTime)
});


const MyMultiPromise = randomPromise( console.log.bind(null,'before everything'));

lab.before(()=>MyMultiPromise);

MyMultiPromise.then( ()=>{
    
    mutatorApi = (k,val) => {
        mutable[k] = val;
        console.log('Just mutating %s',k);
    }
})

lab.beforeEach( 
    () => randomPromise(
        ()=> mutable = JSON.parse(base)
    )
);

describe('----- Updating USERS names -----', () => {

        it('Check an user', (done) => {
            const cloned = JSON.parse(base);
            console.log('Syncrhonous code 1')
            expect(mutable).to.equal(cloned);
            done()
        });
        
        it('Mutates an user', ()=>
            new Promise((res,rej) => {
                mutatorApi('name' , 'Jesus');
                expect(mutable.name).to.equal('Jesus');
                console.log('Promise 1')
                res();
            })
        );
});

describe('----- Updating USERS surnames -----', () => {

        it('Check an user', (done) => {
            
            const cloned = JSON.parse(base);
            console.log('Syncrhonous code 2')
            expect(mutable).to.equal(cloned);
            done()
        });
        
        it('Mutates an user', ()=>
        
            new Promise((res,rej) => {
                
                mutatorApi('surname' , 'Crist');
                expect(mutable.surname).to.equal('Crist');
                console.log('Promise 2')
                res();
            })
        );
        it('New prop to an user', ()=>
        
            new Promise((res,rej) => {
                
                mutatorApi('Age' , 33);
                expect(mutable.Age).to.equal(33);
                console.log('Promise 3')
                res();
            })
        );
});

package.json

{
  "name": "5c098aeb168d61ad588266397ea837a1",
  "version": "1.0.0",
  "description": "",
  "main": "lab weird promises behavior.js",
  "scripts": {
	  "test": "lab index.js --reporter console --threshold 100 --assert code --coverage --verbose",
	  "test:lint": "lab index.js --reporter console --threshold 100 --assert code --lint --lint-errors-threshold 0 --lint-warnings-threshold 0 --coverage --verbose"
  },
  "repository": {
    "type": "git",
    "url": "git+https://gist.github.com/5c098aeb168d61ad588266397ea837a1.git"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "bugs": {
    "url": "https://gist.github.com/5c098aeb168d61ad588266397ea837a1"
  },
  "homepage": "https://gist.github.com/5c098aeb168d61ad588266397ea837a1",
  "dependencies": {
    "code": "^4.0.0",
    "lab": "^13.0.1"
  }
}