[Memory Leak] beforeEach / afterEach appear to leak

[stefanpenner]

the following code (from : source) appears to leak beforeEach and afterEach on the original module. This results in per module leak of the ambient context.

this.testEnvironment = extend( {}, this.module.testEnvironment );
delete this.testEnvironment.beforeEach;
delete this.testEnvironment.afterEach;

Obviously the following, prevents the leaks:

var foo;

module('test', {
  beforeEach() {
    var foo = new Foo();
  },

  afterEach() {
    foo = null
  }
});

but it is tedious and error prone. A much better solution, for those using modules (AMD/CJS/etc), is merely to release the entirely module. Unfortunately, QUnit retaining beforeEach and afterEach per module, prevents a less error prone and tedious solution.

cc @cibernox

[stefanpenner]

A quick spelunk indicates the above offending code is likely just run in the wrong order and incorrect object.

if:

this.testEnvironment = extend( {}, this.module.testEnvironment );
delete this.testEnvironment.beforeEach;
delete this.testEnvironment.afterEach;

becomes:

delete this.module.testEnvironment.beforeEach;
delete this.module.testEnvironment.afterEach;
this.testEnvironment = extend( {}, this.module.testEnvironment );

We release as expected, without any leaks.