Unable to run Rust unittests on binded library

[ziv]

Running Rust testing on binded library generate errors.

Reproduction:
https://github.com/ziv/node-bindgen-unitest-error-reproduction

Expected behavior:

Running tests should pass.

Actual behavior:

Error

 %  cargo test --verbose
 
    Compiling node-bindgen-unitest-error-reproduction v0.1.0 (...)
     Running `rustc ...`
error: cannot find attribute `node_bindgen` in this scope
 --> src/lib.rs:6:7
  |
6 |     #[node_bindgen]
  |       ^^^^^^^^^^^^

warning: unused import: `node_bindgen::derive::node_bindgen`
 --> src/lib.rs:1:5
  |
1 | use node_bindgen::derive::node_bindgen;
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: `#[warn(unused_imports)]` on by default

error: aborting due to previous error; 1 warning emitted

error: could not compile `node-bindgen-unitest-error-reproduction`

Caused by:
  process didn't exit successfully: `rustc --crate-name node_bindgen_unitest_error_reproduction --edition=2018 src/lib.rs --error-format=json --json=diagnostic-rendered-ansi --emit=dep-info,link -C embed-bitcode=no -C split-debuginfo=unpacked -C debuginfo=2 --test -C metadata=51601585b678e8bc -C extra-filename=-51601585b678e8bc --out-dir /Users/ziv.perry/zivcode/node-bindgen-unitest-error-reproduction/target/debug/deps -C incremental=/Users/ziv.perry/zivcode/node-bindgen-unitest-error-reproduction/target/debug/incremental -L dependency=/Users/ziv.perry/zivcode/node-bindgen-unitest-error-reproduction/target/debug/deps --extern node_bindgen=/Users/ziv.perry/zivcode/node-bindgen-unitest-error-reproduction/target/debug/deps/libnode_bindgen-553b1a9a13c1f95a.rlib -C link-arg=-undefined -C link-arg=dynamic_lookup` (exit status: 1)
 

Workaround

Removing #[node_bindgen] decorator works.
Example for output after commented the decorator:

 % cargo test
   Compiling node-bindgen-unitest-error-reproduction v0.1.0 (...)
    Finished test [unoptimized + debuginfo] target(s) in 0.91s
     Running unittests (target/debug/deps/node_bindgen_unitest_error_reproduction-51601585b678e8bc)

running 1 test
test testing::should_sum_numbers ... ok

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s

[nicholastmosher]

Hi @ziv, thanks for opening the issue, and for the great reproduction! I think I see two things happening here:

1. You are importing node_bindgen::derive::node_bindgen at the top-level module, but you are trying to use it inside your example module. Try putting your use statement inside of each module where you use #[node_bindgen].

2. I tried fixing 1 and then saw a new error:

error[E0432]: unresolved import `crate::example::sum`
 --> src/testing.rs:1:5                              
  |
1 | use crate::example::sum;
  |     ^^^^^^^^^^^^^^^^^^^ no `sum` in `example`

error: aborting due to previous error

I think this is due to the fact that node_bindgen actually reads your function body and generates a totally different function from it, which is intended to be called from node rather than Rust. For unit testing, I would suggest making an inner Rust function that does your logic and test against that, then create a wrapper that has the #[node_bindgen] annotation and calls the inner function. Something like this:

#[node_bindgen]
pub fn sum(first: i32, second: i32) -> i32 {
    sum_impl(first, second)
}

pub fn sum_impl(first: i32, second: i32) -> i32 {
    first + second
}

// Then unit test `sum_impl`

Let me know if that pattern works for you!

[sehz]

Seems like this is solved problem. Closing this. Feel to re-open if this doesn't the solve

[sehz]

We should add this to documentation

[ziv]

Hi @nicholastmosher, while your solution is simple to use when my API is minimal, I have a library exports structs and their implementations.

Using this method is practically - copy all my code just to export it.

[sehz]

Test failure happens because actual rust fn sum is hidden:

extern "C" fn napi_sum(
    env: node_bindgen::sys::napi_env,
    cb_info: node_bindgen::sys::napi_callback_info,
) -> node_bindgen::sys::napi_value {
   .....
    fn sum(first: i32, second: i32) -> i32 {

So one way is to move inner fn as peer:

 pub fn sum(first: i32, second: i32) -> i32 {
...
}

extern "C" fn napi_sum(
    env: node_bindgen::sys::napi_env,
    cb_info: node_bindgen::sys::napi_callback_info,
) -> node_bindgen::sys::napi_value {
   .....