Hello:
I've recently been faced with updating an old GS extension, and I
decided to use unit tests for it. The approach I took involved some
tooling to be able to test code using karma with jasmine and PhantomJS,
webpack was used to solve most of the issues I encountered. This should
work for any GJS application. Following are some comments on what I did.
Repository of extension using unit tests:
https://github.com/emerinohdz/power-alt-tab
1. GJS Imports mechanism is replaced with ES6 imports, by defining the
target library to UMD for webpack this shouldn't be a problem.
Webpack creates a single file with all the needed configurations.
2. Since we are using ES6 imports now, there's no problem while
testing. Karma has to be setup with support for webpack though.
3. For unit testing to work fine, I had to include a GS polyfill
(test/polyfill_gs.js). This polyfill only covers what I needed, the
way I needed it, mostly mocking every global GS object needed.
4. Integration testing was not possible, this would be a huge step
forward. Providing some type of test API where things could be
integrated and tested before moving to production would mean faster
delivery of new functionality IMO. This is of course the greatest
challenge.
5. Tests can be run on PhantomJS. For this to work, I had to use a
transpiler (babel) with webpack. This has the added benefit of
generating JS code that is backwards compatible between GS versions,
while allowing us to use ES6 features now.
6. This was all integrated with Travis CI (see the github repo for
reference).
NOTE: I had to keep classes that extend native GS classes using
Lang.Class instead of ES6 classes, because there were some problems with
the transpiled code when calling super constructors. If you are not
using a transpiler for releases, all classes can be refactored to ES6.
I've posted a similar email to the GSE mailing list, but I thought
it would be helpful for any GJS developer looking to create quality code
by applying TDD.
It'll be great to read your thoughts on this approach.
Regards.
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