tl;dr; be careful with your testing strategy, it might break your company. There's some aspects that stand to gain from automated testing, it's important that developers test their work, but in my opinion manual testing is super valuable especially for an early stage start-up.

I was working for a startup that first had the strategy of testing everything, at a point when we didn’t even start working on the product. We spent a horrible ammount of time getting the test system up and running (microservices, browser add-ons), with the UI testing being the most challenging.

But then they also wanted to "move fast and break things", which we did, so we spent an annoying ammount of time fixing breaking tests. This is when the “let’s just delete the test” expression started popping up.

So we ended up with an unmaintained testing system that no one cared about anymore, keeping our build on red because we always had the testing system in the backlog so it was going to be done at one point.

Then, the quality of the codebase started degrading to the point where we’d wake up with features that have been broken for a while and no one noticed it, even though each individual developer was testing their own flows. We had no one / nothing testing the entire system.

At this point, I suggested we hire 1 – 2 manual testers, as our testing strategies are obviously failing, the product is suffering in terms of quality and we could get them for relatively cheap compared to dev-time. I’ve had great success working with manual testers for very complex products with real world repercussions, compared to this tiny start up in dev tooling.

They refused. So they decided we’d do cross functional testing and then test the entire system whenever we’d do a merge. So developer velocity fell from a cliff because we became the manual testers. We still had no customers at this point. Runway got shorter and shorter. And the start-up became a statistic.