CODEWITHSUNDEEP
rust
Dmitry Uvarov
Dmitry Uvarov

Reputation: 703

How to initialize the logger for integration tests?

I have a crate with production code in the src directory and integration tests in the tests directory. The production code uses log macros.

I would like to init a global logger when running the integration tests (e.g. env_logger::init().unwrap();) There are several tests and the test order is not defined, so I don't know in which test I should put the initialize command.

Is there any way I can do this nicely? Perhaps by overriding the tests main function?

Upvotes: 48

Views: 12002

Answers (4)

Steven
Steven

Reputation: 5780

For now, you can just re-initialize the logger at the top of every test and ignore the error. It's not a pretty solution but it works and is perfectly safe.

let _ = env_logger::try_init();

// your test code...

Upvotes: 6

Patrick Tescher
Patrick Tescher

Reputation: 3447

The latest documentation has a recommendation on Capturing logs in tests :: env_logger:

Records logged during cargo test will not be captured by the test harness by default. The Builder::is_test method can be used in unit tests to ensure logs will be captured:

#[cfg(test)]
mod tests {
    fn init() {
        let _ = env_logger::builder().is_test(true).try_init();
    }
 
    #[test]
    fn it_works() {
        init();
        info!("This record will be captured by `cargo test`");
 
        assert_eq!(3, 1 + 2);
    }
}

Upvotes: 16

Konstantin Grech
Konstantin Grech

Reputation: 433

In addition to Danilo Bargen's comment, you can write it in a shorter form:

use std::sync::Once;

static INIT: Once = Once::new();

fn setup() {
  INIT.call_once(env_logger::init);
}

Upvotes: 7

Danilo Bargen
Danilo Bargen

Reputation: 19452

You can use something like this:

use std::sync::Once;

static INIT: Once = Once::new();

/// Setup function that is only run once, even if called multiple times.
fn setup() {
    INIT.call_once(|| {
        env_logger::init().unwrap();
    });
}

Then simply call setup() in the beginning of each test.

Originally based on this blogpost.

Upvotes: 48

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