Tests are an intrinsic part of any software engineering culture. When we were shopping for a platform to build Toda, we didn’t want to end up making decisions which would impede our ability to test the system at every level. Anything we chose would need to support unimpeded testing including:

  • Unit tests of all core library functions
  • Integration tests of the platform code, including a stubbed network layer
  • End-to-end functional testing of native clients

Test frameworks are quite diverse, and many cannot support the full spectrum of tests from unit tests to functional tests of native clients. Furthermore, the overall architecture can impede these efforts significantly. Close-coupling between components makes stubbing simulated modules for tests much more difficult, and often involves more magical code which can interfere in normal operation.

We wanted our cake and to eat it too: ideally, we wanted a test suite written in a single, consistent language across all scales of test. This meant no special APIs for driving UI (like Selenium), no fragile, time-intensive recorded UI sessions, and no special test description languages.

Using ClojureScript across our entire architecture paid dividends again: not only did it mean only writing tests against a single target, but it also meant the tests could be written in the same language (and stubs were trivial)!

When it comes to functional testing the native apps for our joint venture, TQF, Figwheel and a repl turn a chore into a spectacle. Since we can drive the clients (and verify their internal state) from our editors, functional tests became very enjoyable to write and watch. Interactively navigating by code, for example, is a one-liner:

toda.views=> (navigate :History)

…And back home:

toda.views=> (navigate-home)

The real upshot to this is that more tests get written. I’m not chasing down engineers who ‘owe’ us tedious, time-intensive UI tests: they’re writing the few necessary lines themselves to confirm their code, just like with unit tests. And ultimately, it means a more robust, trustworthy user experience.

Adam