Comparing test runners versus frameworks
Historically, tests for JavaScript targeting web browsers could not be just written and run automatically. The main reason was that this involved dealing with a real browser. There was no way to just pretend to run in the browser. For this reason alone, the first tools in that space have either been scripts or whole websites evaluating JavaScript or browser automation tools. The latter actually forms its own category – being at the heart of modern end-to-end tests.
The main driver for running the tests – historically, for starting everything that needs to be running to actually perform tests – is called a test runner. One of the first very successful test runners in the JavaScript space was Karma. The job of Karma was to spin up a server that runs a website hosting the tests, which are targeting JavaScript code that should run in a browser. Karma then opened available browsers to access the hosted website running the...
