Angular vs React vs Vue
Yes, from my experience it can.

Regarding modular programming: Vue is rather similar to React in this matter.

Components can be created and treated rather similarly to the way one treats React.Component objects. While the two frameworks are different, the mindset for dealing with components is essentially the same. 

This means that user interactions are also somewhat identical. I'm not entirely sure what you mean by "complex", but these Vue components can handle events (such as clicking etc.)

As for unit testing, well: Their guide page does a better job at explaining than I do. Essentially, one can use Jasmine or other UnitTest frameworks, and the Vue instance is the mediator between regular ol' javascript, and the components you want to test.

This mediation by the Vue instance brings me to the final point: Vue doesn't exactly separate concerns in this regard. Most things are channeled through this instance. I haven't looked into it enough to be sure, but my guess is that it's more like a factory than a container for other things.
This would make it much more concern-separated. But again, Vue.js knows better than I do. A more in-depth explanation can be found in this medium.com post

So, while Vue might seem more shallow at first, I find that it isn't. It's just somewhat different than the other two, but more similar to React.