Mocha before() & beforeEach() execution order with nested describe()

before.js

'use strict';

describe('mocha before hooks', function () {
	before(() => console.log('*** top-level before()'));
	beforeEach(() => console.log('*** top-level beforeEach()'));
	describe('nesting', function () {
		before(() => console.log('*** nested before()'));
		beforeEach(() => console.log('*** nested beforeEach()'));
		it('is a nested spec', () => true);
	});
});

//   mocha before hooks
// *** top-level before()
//     nesting
// *** nested before()
// *** top-level beforeEach()
// *** nested beforeEach()
//       ✓ is a nested spec
//
//
//   1 passing (8ms)

top level beforeEach initializes something that is used by the nested before

From the example above the nested before() is called before the top level beforeEach().

So if the nested before() relies on the top level beforeEach() to initialize something, the result might be undefined or null