Friend of mine: so I wonder how do you test your applications in the startup?

Me: testing? *grabs his coffee laughing*

Actually we have a complete build pipeline from commit/pull-request to dev and production environments. No tests. Really. We are in rapid product development / research state.

We change technologies and approaches like our underwear (and yeah, this is frequently). If we settled some day and understood the basic problems of the whole feature palette, we'll talk about tests again.