What does it mean to “shift testing left”?

What does it mean to “shift testing left”?

I used to think shifting left meant starting all these testing activities earlier in the process, but I realise it is more than that: it means doing different things. Shifting left on testing means thinking about architecture and design differently, considering different stakeholders early and continually. Which in turn means shifting left on security, accessibility, and all the other dimensions of quality that we should care about. So shifting left on testing motivates all kinds of assurance activities, which can stop us over-investing in a solution that was never going to work. It is like TDD on steroids.

As an unintended consequence, we can remove much of the traditional work that testers would have to do downstream when they only have late sight of the product. Again, we aren’t doing that work earlier, we are setting ourselves up to never need it at all!