Ruby Conf 12 - Boundaries by Gary Bernhardt

What this video covers

Gary Bernhardt's RubyConf 2012 talk on testing in isolation without mocking everything. It goes through behavior versus data, mutation versus immutability, and how a functional core with an imperative shell yields natural isolation and parallelism.

Why it surfaced in Hacker News

HN recommends it as the canonical presentation of 'functional core, imperative shell' and a practical answer to unit versus integration testing.

Recommendation context

Short excerpts from positive mentions. Open the source to read the full Hacker News discussion.

“Gary Bernhardt's awesome "Boundaries" talk”

“I can't more strongly recommend watching this video”

“I highly recommend this video for a more philosophical take on how to do "impure FP" without OO”