Add DEP: JavaScript Tests

[treyhunner]

This is a rough draft for a DEP detailing a path to adding JavaScript unit tests to Django.

This proposal currently only details my recommendation for a test suite and a native JS testing process (without a Python wrapper), including my reasoning.

I have also included some open questions that still need to be addressed.

Related django-developers mailing list thread

[loic]

Most JavaScript in Django is tested through Selenium, it's far from ideal but it's something, this statement needs to be revisited IMO.

[carljm]

The Selenium tests are high-level functional/integration tests, not unit tests. Unit tests run much more quickly and test the JS API rather than the in-browser behavior of the JS.

[loic]

I understand, but this posted right below "Code without tests is broken as designed." seems to imply that Django's JS is untested, that's not the case.

[carljm]

True, it would be good to clarify.

[treyhunner]

@loic good point. I am making a guess (albeit one with good odds) that portions of the JavaScript code are not executed.

I've noticed in my own code that JavaScript tests often require more mocking than Python code because of the event-driven nature of JS. So my guess about the lacking nature of the existing tests may not be far from reality, but it's hard to tell for sure without a code coverage tool in place.

I should also note sinon for mocking and a code coverage tool (probably istanbul unless we use karma).

[treyhunner]

Changes:

1. Clarified the rationale
2. Added counter-arguments against the perceived problem of running the automated tests using Node.js
3. Added a high-level migration path

[akaariai]

We are trying to get the DEP process started again.

Could you squash the commits into one? After that we can merge the proposal to drafts.

[treyhunner]

@akaariai commits squashed. Thanks for restarting the process.