How does promise.all() implementation behave in bluebird?

testAll.js

var Promise = require('bluebird');

var a=0, b=0, c=0, d=0, e=0;
var tests = [
  Promise.delay(5000).then(function(){a++; return Promise.resolve("hell5");}),
  Promise.delay(1000).then(function(){b++; return Promise.resolve("hell4");}),
  Promise.delay(3000).then(function(){c++; return Promise.resolve("hell3");}),
  Promise.delay(2000).then(function(){d++; return Promise.reject("heaven2");}),
  Promise.delay(1000).then(function(){e++; return Promise.resolve("hell1");})
];

return Promise.all(tests)
  .then(function(){
    console.log('then', arguments);
    return Promise.resolve();
  })
  .catch(function(){
    console.log('catch', arguments);
    console.log('a', a);
    console.log('b', b);
    console.log('c', c);
    console.log('d', d);
    console.log('e', e);
  });