Bug fix for the last test of Allergies

[k0pernicus]

The last test must not contains false positives, but 509 is greater than 255 so expected must contain Allergen::Peanuts.

[petertseng]

I think the test is correct as-is - 509 & 255 is 253, so the result for 509 should be the same as the result for 253, and the result for 253 does not contain Peanuts

Edit: correction in my comment: 253 instead of 252.

[petertseng]

This test is present in the Rust track because it is present in the common test data at https://github.com/exercism/x-common/blob/master/exercises/allergies/canonical-data.json - if we wish to change it, it is best to change it there so that all tracks can update their tests

A discussion for numbers > 255 is at exercism/problem-specifications#224

[k0pernicus]

Ok so write directly in the README file that if the numbers is greater than 255, you have to make a & with it?

I think it exists a better solution to this end, returning a Result type creating the structure Allergies.
This type can return the Self object for Allergies if the uid given as parameter is correct - else an Error type and we can't continue after that?

[petertseng]

Yes, we should discuss at exercism/problem-specifications#224 whether the correct solution is to & 255 or say that numbers greater than 255 are errors.

[IanWhitney]

I suggest we close this until exercism/problem-specifications#224 is resolved