We specifically looked at CanJS, Backbone and EmberJS. None of which have testability as a core feature. CanJS and Backbone barely mention how to do it, EmberJS has one tiny page on integration testing. Which practically means there isn't a established right way to do testing. And you as a developer need to figure it all out.
I personally think ember has the best testability story for both unit and integration testing. The screencast below shows how to get started with ember / QUnit and karma
Angular's dependency on the DOM for rendering will always make testing it very difficult. This will continue their move towards feature based testing. Feature tests have their use, but they do not scale and provide the least useful insight into why something is failing. They are also notoriously slow, so once you have a large test suite, it can easily take 20 minutes or more for feedback. I have worked with feature based test suites that take 2 hours to run. It wasn't fun.
Ember are improving this however, with the ember-testing package: https://github.com/emberjs/ember.js/tree/master/packages/emb... Backbone has countless tutorials on how to test, but it's not built into the framework.