有哪些方法可以运行 Rust cargo test 并让测试运行器将任何日志 output 显示到控制台 stdout 或 stderr？

Question

I've learned:

• cargo test -- --nocapture which tells Cargo to show output instead of hiding output; I'm interested in seeing output for successful tests, not just failed tests.
• env_logger crate which enables using an environment variable to set the log level.

I'm seeking any similar ways, and ideally any official reference guide that shows good ways to accomplish this.

Answer 1

Here's one solution that is working for me.

Cargo.toml dependency:

env_logger = "*"

Demo source code:

use log::*;

pub fn foo() -> bool {
    info!("hello world");
    true
}

#[cfg(test)]
mod tests {
    use super::*;
    use env_logger;
    #[test]
    fn test_foo() {
        env_logger::init();
        assert!(foo());
    }
}

Command:

RUST_LOG=info cargo test -- --nocapture   

Answer 2

The Rust book shows how to do this .

The relevant part of that section:

If we want to see printed values for passing tests as well, we can tell Rust to also show the output of successful tests with --show-output.

cargo test -- --show-output