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> The people at Twitter who understood the system and could predict the side effects were all fired or left And never created sufficient testing.

bandyaboot 3y ago
Yes, because Elon Musk would never scrap existing pre-release testing procedures.
whatever1 3y ago
There is never sufficient testing. If there is, then you have a formal proof for your algorithm.
- kybernetikos 3y ago
  Beware of bugs in the above code; I have only proved it correct, not tried it. – Donald Knuth It's not just hypothetical either. There was a bug in a sorting algorithm a few years back that had been 'proved' correct. I think it was to do with numbers wrapping, and that hadn't been considered in the mathematical proof.
  - Regic 3y ago
    WPA2 also had an exploit (KRACK) while the handshake algorithm itself was "proven to be secure". Formal verification is a powerful tool but it does not guarantee bug-free code: it merely guarantees that the particular bugs you checked for are not possible.
greenthrow 3y ago
You can't write tests for the changes someone might make in the future.
- onion2k 3y ago
  That's exactly why you write tests. You want to be sure future changes don't break present functionality, especially if the future changes are being done by someone who doesn't understand your part of the system.
  - SketchySeaBeast 3y ago
    But if you need to make an update to a core system that'll necessitate updating the tests and you're back to flying blind.
    - onion2k 3y ago
      It shouldn't require updating the tests, so long as you're testing the functionality rather than the implementation.
  - greenthrow 3y ago
    You write tests for your code as it exists to make sure it functions. You cannot write tests for every conceivable change that someone else might make in the future that either mis-uses your code or adds new code inbetween that didn't previously exist. You need the people who add that new code to write new tests. Something that it seems the remaining engineers at Twitter do not have time for.

bandyaboot 3y ago

Yes, because Elon Musk would never scrap existing pre-release testing procedures.

whatever1 3y ago

There is never sufficient testing. If there is, then you have a formal proof for your algorithm.

kybernetikos 3y ago
Beware of bugs in the above code; I have only proved it correct, not tried it. – Donald Knuth It's not just hypothetical either. There was a bug in a sorting algorithm a few years back that had been 'proved' correct. I think it was to do with numbers wrapping, and that hadn't been considered in the mathematical proof.
- Regic 3y ago
  WPA2 also had an exploit (KRACK) while the handshake algorithm itself was "proven to be secure". Formal verification is a powerful tool but it does not guarantee bug-free code: it merely guarantees that the particular bugs you checked for are not possible.

greenthrow 3y ago

You can't write tests for the changes someone might make in the future.

onion2k 3y ago
That's exactly why you write tests. You want to be sure future changes don't break present functionality, especially if the future changes are being done by someone who doesn't understand your part of the system.
- SketchySeaBeast 3y ago
  But if you need to make an update to a core system that'll necessitate updating the tests and you're back to flying blind.
  - onion2k 3y ago
    It shouldn't require updating the tests, so long as you're testing the functionality rather than the implementation.
- greenthrow 3y ago
  You write tests for your code as it exists to make sure it functions. You cannot write tests for every conceivable change that someone else might make in the future that either mis-uses your code or adds new code inbetween that didn't previously exist. You need the people who add that new code to write new tests. Something that it seems the remaining engineers at Twitter do not have time for.