The saying goes that the projects needs to have a significant size or significant risk profile to accommodate for testing activities. Some would say that start-ups would never have room for testers and light weight agile teams neither.
But there is always testing going on.
It’s just implicitly (or implied) there is in fact testing going on. The team members even in small teams considers the risks and mitigate them. They considers the risk, the minimum viable quality and timing of their delivery. If it’s buggy, hey no problem – in context. If testers aren’t really worth the investment – then fine, – in context (H/T Anne-Marie Charrett).
When the cost of more explicit testing activities is less than the information that testing can offer – then testing happens. Then more explicit testing activities have a positive ROI of information.
“Testing is a sunk cost – but the information it provides – must bring value to the business”
A little explicit testing in a startup, is usually enough. But if you are building an app for a broader audience, then explicit testing on some devices might be very important to you. Remember when you work on something you are using both parts of your brain.