Template helpers and callbacks can easily be unit tested. The only problem is to get to them you have to rely on private properties. For example to test a onRendered callbacks you'd have to use:

let templateInstance = sinon.createStubInstance(Blaze.TemplateInstance);
templateInstance.$ = sinon.spy($);

Template[templateName]._callbacks.onRendered.call(templateInstance);

//Insert assertions here

To prevent boilerplate and having to search replace your whole project when MDG changes _callbacks to __callbacks. This package was made, when using this package instead you can write:

let templateInstance = TemplateTestHelpers.getMockTemplateInstance();
TemplateTestHelpers.getTemplateOnRenderedFunction(templateName).call(templateInstance);

//Insert assertions here

Atmosphere

Usually you'd put this package in the api.use of the onTest clause of a package you want to test.

Example:

  api.use([
    'ecmascript',
    'mike:mocha-package@0.5.8',
    'practicalmeteor:sinon',
    'practicalmeteor:chai',
    'underscore',
    'mdj:template-test-helpers@0.2.0',
    'packageYourTesting' //Make sure template-test-helpers is loaded before the package containing the template you want to test
  ]);

Important note: to be able to catch the raw event handlers, this package contains a override of Template.prototype.events. So to ensure this package works like intended make sure you specify this package BEFORE the package containing the templates you want to test.

TODO: I will write more documentation soon. For now just check the code in the client directory.