

Unit tests are exactly for code that is often rewritten, because it ensures that whatever interface still behaves the same, regardless of the implementation. This a large portion of the point of unit tests: not for testing the initial implementation but confirming that any subsequent implementation behaves the same.








Of course they won’t make it in house, they’ll contract some company to do it as cheap as possible, and it will run like hot garbage and probably have a tone of bugs and security vulnerabilities.
Remember the track and trace app they spent £10 Billion on?