Adds `before` and `after` hooks to QUnit to enable one-time setup and teardown steps. Similar to Mocha.

qunit-before-after.js

// Add the `before` hook
QUnit.moduleStart(function() {
  // QUnit is weird in that once a module starts, it is considered the `previousModule` and not the `currentModule`.
  let previousModule = QUnit.config.previousModule;
  let testEnvironment = previousModule && previousModule.testEnvironment;
  let before = testEnvironment && testEnvironment.before;

  // If the module has a `before` function, call it with the `testEnvironment` as the context.
  if (before && typeof before === 'function') {
    before.call(testEnvironment);
  }
});

// Add the `after` hook
QUnit.moduleDone(function() {
  // QUnit is weird in that once a module starts, it is considered the `previousModule` and not the `currentModule`.
  let previousModule = QUnit.config.previousModule;
  let testEnvironment = previousModule && previousModule.testEnvironment;
  let after = testEnvironment && testEnvironment.after;

  // If the module has a `after` function, call it with the `testEnvironment` as the context.
  if (after && typeof after === 'function') {
    after.call(testEnvironment);
  }
});