Access function from a different module in rust

Question

If I have the following:

├── Cargo.lock
├── Cargo.toml
├── main
│   ├── Cargo.toml
│   └── src
│       └── main.rs
├── module2
│   ├── Cargo.toml
│   └── src
│       ├── lib.rs
│       └── builder.rs

Where the Cargo.toml file in the root is the following:

[workspace]

members = [
    "main",
]

I want to access a function from builder.rs in main when testing(i.e. cfg(test)), how can I do so?

Module2 is a library(it was created by running cargo new module2 --lib.

I tried the following:

// module2/builder.rs

pub fn build() { /*...*/ }

// module2/lib.rs

#[cfg(test)]
mod mock;

#[cfg(test)]
pub use mock::build;

// main/Cargo.toml
// ...
[dependencies]
module2 = { path = "../module2" }

// main.rs

#[cfg(test)]
use module2::build;

/*
...
*/

This doesn't work and I get the following error:

error[E0432]: unresolved import `module2::build`
 --> main/src/main.rs:3:5
  |
3 | use module2::build;
  |     ^^^^^^^^^^^^^^ no `build` in the root

@ChayimFriedman Yes, it doesn't make any difference if it was in my workspace. — Szegoo
– Szegoo, Commented Aug 17, 2022 at 9:12

Chayim Friedman · Accepted Answer · 2022-08-17 09:16:05Z

1

test of module1 is not test of main: each crate gets cfg(test) turned on only when it itself is being tested, not when a dependency of it is being tested.

You can use cfg(debug_assertions) as an approximation or a custom feature.

answered Aug 17, 2022 at 9:16

Chayim Friedman

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