Honestly, I am not a huge fan of testing in general, especially on the front-end; blasphemy (smile). My preference is to write clean declarative code and leave it at that. This is because I am reacting to all the attempts (that I have been involved in) at forcing developers to write unit tests with code coverage requirements fail (to deliver on code quality).
At the same, with a larger team (business analysts, developers, etc.), I often see a gap between the two in describing the app’s behavior. Assuming that we are focused on writing integration tests (features), I actually like the declarative structure of the tests (the Gherkin syntax) as it provides us something to build off of.
On my next larger project, it is fully my intention to follow this approach.