When I was writing unit tests for my side project, I found that the foreign key cascade funtionality didn't work as expected.

I guess the name SQLite means it's a (relatively) light weight database. All the data will be stored in just one database file. In this case, the backup task would be pretty easy. Basically just copy and paste, then end of story. Why we don't see those temporary files normally? Although it has only one file in the end …