share code between integration tests and in-line tests in rust

Question

In another larger project I have lots of helper functions and trait definitions for my tests. I want to use these both when I test the public interface of the library and when I test private functions.

Right now I am trying to use workspaces to achieve this but without success. This is the project structure of my minified example:

.
├── Cargo.lock
├── Cargo.toml
├── mylibrary
│   ├── Cargo.toml
│   ├── src
│   │   └── lib.rs
│   └── tests
│       └── alltests.rs
└── testutil
    ├── Cargo.toml
    └── src
        └── lib.rs

And the file contents:

//testutil/src/lib.rs
use mylibrary;

pub fn add_custom(x: i32, y: i32) -> mylibrary::Custom {
    mylibrary::add(mylibrary::mk_custom(x), mylibrary::mk_custom(y))
}

---

// mylibrary/tests/alltests.rs
use mylibrary;
use testutil;

#[test]
fn adds_correctly() {
    assert_eq!(testutil::add_custom(2, 3).value, 5)
}

---

// mylibrary/src/lib.rs
#[cfg(test)]
use testutil;

pub struct Custom {
    private_field: i32,
    pub value: i32,
}

pub fn mk_custom(v: i32) -> Custom {
    Custom { private_field: v, value: v }
}

pub fn add(x: Custom, y: Custom) -> Custom {
    let result = x.value + y.value;
    Custom { private_field: result, value: result }
}

#[test] // this test successfully accesses the private field
fn private_field_test_1() {
    let result = add(mk_custom(2), mk_custom(3));
    assert_eq!(result.value, result.private_field)
}

#[test]
fn private_field_test_2() {
    let result = testutil::add_custom(2, 3);
    assert_eq!(result.value, result.private_field) // <-- error
}

---

> cargo test
...
error[E0616]: field `private_field` of struct `mylibrary::Custom` is private
  --> mylibrary/src/lib.rs:28:37
   |
28 |     assert_eq!(result.value, result.private_field)
   |                                     ^^^^^^^^^^^^^ private field
...

I understand that I'm going through the public interface when I use this helper function which prevents me from reading the private field. Unfortunately the only solution I can come up with on my own is to copy and paste the helper code which isn't ideal.

question from:https://stackoverflow.com/questions/65910349/share-code-between-integration-tests-and-in-line-tests-in-rust

Answer 1

Waitting for answers