[snhly]

Lichess being a project that is 85% written by one guy, and all other changes approved and read by him, he may have felt confident (until now) that he could maintain all the complexity of the software in his own head, and recall what to do and where to do it whenever he made changes. Seems bonkers to most of us writing software in teams, but compare this choice of workflow to ones made by others in similar situations: programmers in academia, who often work entirely alone, or Linus Torvalds in earlier versions of the kernel. Skipping testing is a common choice, especially when working alone and with a typed language. I could see Thibault bringing tests in now however. They would not have caught much in this case, because it seems like the problem came to light only when the software started running with real users.

[bravetraveler]

While I do agree, these folks deserve a break... see my other comment in this thread RE: load testing

It's not particularly expensive or difficult, but it does need investment