Add a template for a group of methods from one module

[bugRanger]

I'd like to share a solution to the problem of writing identical tests.

My project uses multiple implementations of the same trait. All tests have the same logic for verifying the behavior of the trait implementation; the only difference is in the #[fixture] section, where the implementation under test is selected.

The solution I propose is similar to #[template], except that we create a template for the entire module and, in this module, mark the methods that should be excluded from the template. The excluded methods are expected to be implemented with the necessary modifications wherever the template is used.

[la10736]

It's a way to implement what we called contract tests ... now this name is used for something different but the idea is "I would test the trait contract against different implementation".

Lot of years ago it was possible in rust import the same module file from different source code and I used this "wrong behaviour" to load different fixture from the same test file.

Anyway, I love this idea.

I have to fix the CI... I guess 😄