Comment by 9rx
21 hours ago
Not likely. The alternative was for them to modify SQLite without the test suite and no obvious indication of what they would need to do to try to fill in the gaps. Modifying SQLite with its full test suite would be the best choice, of course, but one that is apparently[1] not on the table for them. Since they have to reimagine the test suite either way, they believe they can do a better job if the tests are written alongside a new codebase.
And I expect they are right. Trying to test a codebase after the fact never goes well.
[1] With the kind of investment backing they have you'd think they'd be able to reach some kind of licensing deal, but who knows.
I don't get this. In their own rust implementation they have to write and use their own test and they still don't have access to the proprietary sqlite tests. So their implementation will necessarily be whatever they implement + whatever passes their tests. Same as it would be if they forked sqlite in C. (Plus they would have the open source tests). Am I missing something?
You are missing that HN accounts needlessly overthink everything, perhaps?
Otherwise, I doubt it. They have to write the tests again no matter what. Given that, there is no downside to reimplementing it while they are it. While there is a big upside: Trying to test something after the implementation is already written never ends well.
That does not guarantee that their approach will succeed. It is hard problem no matter how you slice it. But trying to reverse engineer the tests for the C version now that all knowledge of what went into it in the first place is lost is all but guaranteed to fail. Testing after the fact never ends well. Rewriting the implementation and tests in parallel increases the chances of success.