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document updated 6 months ago, on Jun 3, 2022

"Software Engineering at Google: Lessons Learned from Programming Over Time"

A book written by Titus Winters, Tom Manshreck, and Hyrum Wright. First edition published in March 2020.

"Shifting Left"

In Chapter 1, the book has a section called "Shifting Left":

"One of the broad truths we've seen to be true is the idea that finding problems earlier in the developer workflow usually reduces costs. Consider a timeline of the developer workflow for a feature that progresses from left to right, starting from conception and design, progressing through implementation, review, testing, commit, canary, and eventual production deployment. Shifting the problem detection to the 'left' earlier on this timeline makes it cheaper to fix than waiting longer"

This concept doesn't originate at Google, and there have been several articles written about it:

Many of these articles compare old-style waterfall with newer styles of development. Or they focus on testing only. In my mind, "shift left" is a general philosophy that applies to many different things. In general, the sooner in the development lifecycle that you can move a particular process, the better things will be.