I don't necessarily buy it either, but TFA talks about the test suite. They basically pulled 2k unit tests and 400 E2E tests from Next and made sure they all passed.
Even then I still don't think passing all the tests means you duplicated something. That would be a naive understanding of the reality of tests.
Even then I still don't think passing all the tests means you duplicated something. That would be a naive understanding of the reality of tests.