It is possible to mock file modules?

[128f]

I have a file somefile that is just a set of functions.
I am using pub mod somefile, and then doing use somefile::{foo, bar}.
I want to mock the functions coming from the file, but I don't want to rewrite the interface.

I have seen #219, but it seems the suggestion there is to rewrite all function signatures in the same place I do pub mod somefile.

My only option seems to be to introduce an internal module baz into somefile,
which I can then apply cfg_attr(test, automock) to,
and then change my references to use somefile::baz::{foo,bar}.

Is this the only way? Or is there a way to automock somefile without rewriting the interface to it?

[asomers]

You could do something like this in somefile.rs:

// somefile.rs
use cfg_if::cfg_if;
use mockall::automock;

#[automock]
pub mod inner {
    pub fn foo(x: u32) -> u32 {...}
}

cfg_if! {
    if #[cfg(test)] {
        pub use mock_inner::foo;
    } else {
        pub use inner::foo;
    }
}

That approach has the advantage that you don't have to modify any other file. Alternatively, if you really don't want to modify somefile.rs, you could create mock_somefile.rs which repeats the function definitions like this, and then use #[double] in the other files

// mock_somefile.rs
use mockall::automock;

#[automock]
pub mod inner {
    pub fn foo(x: u32) -> u32 {unimplemented!()}
}

[128f]

Your first thing was almost exactly what I was looking for...
I could probably do something like pub use mock_inner::*;, right?

But what about modules from external crates, where I can't make edits introducing an intermediate module?
Is that OOS/unimplemented in this crate?

[asomers]

Yes, glob imports will work. As for modules from external crates, you must repeat the definition somehow. Probably something close to my second example is what you want.