"It was just maintained by one person" has no bearing on the cost of maintaining.
> It’s a unit test framework
It's not a unit test framework. It reaches into the internals of React to make it behave as though it's running in a real environment. It requires intense knowledge of how React works under the hood, and the design requires it to be compatible with lots of old versions of React as well as the latest version.
Honestly I'm not sure why you are so dismissive of the incredible amount of effort that's gone into making it work at all and how much effort it would take it make it work for the latest version of React.
> It’s a unit test framework
It's not a unit test framework. It reaches into the internals of React to make it behave as though it's running in a real environment. It requires intense knowledge of how React works under the hood, and the design requires it to be compatible with lots of old versions of React as well as the latest version.
Honestly I'm not sure why you are so dismissive of the incredible amount of effort that's gone into making it work at all and how much effort it would take it make it work for the latest version of React.