Reusable set of tests

[la10736]

Can be useful create a way to make a set of tests reusable. In #66 we observed that this can be done by create a macro that can decorate test functions by the rstest attribute that define all needed cases and values.

Write these macro is tricky and cannot be assumed as general pattern. From rust 1.40 by rust-lang/rust#64035 (comment) we can write a functional macro to generate macros. We can start to write it in rstest crate and then move it in a separate crate.

[la10736]

TODO:

• Document rstest_reuse code
• Update rstest docs to redirect to rstest_reuse and publish a new version

[la10736]

Done