The emphasis is mine, and if you replace every occurrence of the word “product” with “service” in the excerpt above, it captures my belief about the best we can hope to achieve with pre-production testing of microservices, in that, pre-production tests are largely superficial.
This seems to be a mis-read. The important word is ‘unless’. The authors are saying that you must explore, always. Since the book was published, the more relevant question is, ‘what is the alternative to exploring?’.
Testing in production is an alternative. However, I don’t think it is either-or with testing in pre-prod.