This is a really good read and starter for the general idea of "Specification by Example". Unlike many other books related to coding it contains not a single line of code and just a few examples how data tables and given/when/then syntax can look like. The book is packed with real world examples and comments from active practitioners and concludes with a bit more information about the transformation of the mentioned companies.
Specification by Example: How Successful Teams Deliver the Right Softwarevon Gojko AdzicManning Publications