[crehn]

This should nearly always include writing integration tests (that run on every change) to ensure you can refactor with confidence.

If there are no tests, the team will waste a ton of time anxiously monitoring and reasoning about the messy code and the impact of their changes.

[sdoering]

I do. I even implemented tests for tracking code to be developed locally (including mocks).

This way I'm able to quickly and confidently refactor as well as add to existing tracking code (web analytics).