Fix for: Tests in fuzz directory [issue #91]

[kiminuo]

• Move duplicate_crash_2 test to semantic.rs
• Move extend_vec_from_hex to lib.rs (de-duplicate)

Fixes #91

[kiminuo]

https://github.com/apoelstra/rust-miniscript/pull/96/files#diff-4374b9b87c971ea1a2293a875f41efabR4 is not that nice. It would be nicer to put it somehow to https://github.com/apoelstra/rust-miniscript/blob/master/fuzz/Cargo.toml. Not sure how. Rust gurus are welcomed here :-)

[sanket1729]

Hi @kiminuo , even I am not sure what would be the best way to address this. I also made an attempt for this in #95 .

My idea was to simply put those in README. My understanding was that code should not be a part of fuzz repo at all. We had it because it was easy to reproduce crashes. So, whenever some contributor wants to reproduce a crash, they can paste the code from README, debug the crash, remove the crash code before we merge the PR.
We can wait for @apoelstra's opinion on how to address this.

[kiminuo]

Hi @kiminuo , even I am not sure what would be the best way to address this. I also made an attempt for this in #95 .

Your PR looks very good. A lot of goodies.

My idea was to simply put those in README. My understanding was that code should not be a part of fuzz repo at all. We had it because it was easy to reproduce crashes. So, whenever some contributor wants to reproduce a crash, they can paste the code from README, debug the crash, remove the crash code before we merge the PR.

To be honest, I don't find that really user friendly. But it might be what @apoelstra had in mind, I don't know.