This is interesting because it’s also one of SQLite’s monetizations. SQLite is in the public domain, but you need a commercial license to access their TH3 test harness with 100% branch coverage used to validate SQLite on different platforms.
Source: https://corecursive.com/066-sqlite-with-richard-hipp/
HN Discussion: https://news.ycombinator.com/item?id=27718701