Testability and low defect rates must be baked into code from the start.
This talk covers how to Pair Program, what benefits you can expect from adopting this as a 100% committed activity, and what you'll need to overcome.
I've always been a fan of the XP practices of Pairing and TDD, but recently I’ve moved from intellectually believing that pairing was a good idea, to a deep connection with the behaviour it encourages and the outcomes that it produces.
Stats show us how much it costs to find bugs in code through testing after the code is complete, so our drive must be to produce better code. This better world needs the skills of developers and testers, and pairing allows us to collaborate in better ways to produce quality software.
A conversational explanation of the topic from a developer's point of view is covered in my blog: https://beingrealblog.wordpress.com/2018/03/29/impressed-with-pair-programming/