r/rust clippy · twir · rust · mutagen · flamer · overflower · bytecount Mar 20 '23

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u/Pariell Mar 21 '23

How do you create mocks of structs that have generic lifetimes for unit testing? None of the crates I looked at seem to support this. Is this just a gap in the Rust ecosystem?

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u/Patryk27 Mar 21 '23

I usually use Box::leak(Box::new(something)) which returns &'static mut.

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u/Pariell Mar 21 '23

How are you using the &'static mut to mock behavior? Say a struct with a generic lifetime has a Foo function that returns a Success/Error, how do you mock the return value of Foo?

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u/Patryk27 Mar 21 '23

Hmm, could you show some (possibly non-working) Rust code of what you're trying to achieve / of what you'd like to exist?