I think it was George Dinwiddie that first coined the term “3 Amigos” in agile development around 2009. The analogy was akin to the movie from the mid 90’s by the same name. The Amigos in the agile sense are functional roles:
- Developer(s);
- Tester(s);
- and the Business Analyst or the Product Owner.
It could literally mean more than three as well. The point was, balanced collaboration in agile teams across these roles. George was alluding to these roles from an Acceptance Test Driven Development (ATDD) perspective. He wanted these three constituencies to be heavily collaborative (conversations) around the Acceptance Tests or Acceptance Criteria for each user story.