vendor/tracing-0.1.37/tests/filters_are_reevaluated_for_different_call_sites.rs

// Tests that depend on a count of the number of times their filter is evaluated
// cant exist in the same file with other tests that add subscribers to the
// registry. The registry was changed so that each time a new dispatcher is
// added all filters are re-evaluated. The tests being run only in separate
// threads with shared global state lets them interfere with each other
#[cfg(not(feature = "std"))]
extern crate std;

use tracing::{span, Level};
use tracing_mock::*;

use std::sync::{
    atomic::{AtomicUsize, Ordering},
    Arc,
};

#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
#[test]
fn filters_are_reevaluated_for_different_call_sites() {
    // Asserts that the `span!` macro caches the result of calling
    // `Subscriber::enabled` for each span.
    let charlie_count = Arc::new(AtomicUsize::new(0));
    let dave_count = Arc::new(AtomicUsize::new(0));
    let charlie_count2 = charlie_count.clone();
    let dave_count2 = dave_count.clone();

    let subscriber = subscriber::mock()
        .with_filter(move |meta| {
            println!("Filter: {:?}", meta.name());
            match meta.name() {
                "charlie" => {
                    charlie_count2.fetch_add(1, Ordering::Relaxed);
                    false
                }
                "dave" => {
                    dave_count2.fetch_add(1, Ordering::Relaxed);
                    true
                }
                _ => false,
            }
        })
        .run();

    // Since this test is in its own file anyway, we can do this. Thus, this
    // test will work even with no-std.
    tracing::subscriber::set_global_default(subscriber).unwrap();

    // Enter "charlie" and then "dave". The dispatcher expects to see "dave" but
    // not "charlie."
    let charlie = span!(Level::TRACE, "charlie");
    let dave = charlie.in_scope(|| {
        let dave = span!(Level::TRACE, "dave");
        dave.in_scope(|| {});
        dave
    });

    // The filter should have seen each span a single time.
    assert_eq!(charlie_count.load(Ordering::Relaxed), 1);
    assert_eq!(dave_count.load(Ordering::Relaxed), 1);

    charlie.in_scope(|| dave.in_scope(|| {}));

    // The subscriber should see "dave" again, but the filter should not have
    // been called.
    assert_eq!(charlie_count.load(Ordering::Relaxed), 1);
    assert_eq!(dave_count.load(Ordering::Relaxed), 1);

    // A different span with the same name has a different call site, so it
    // should cause the filter to be reapplied.
    let charlie2 = span!(Level::TRACE, "charlie");
    charlie.in_scope(|| {});
    assert_eq!(charlie_count.load(Ordering::Relaxed), 2);
    assert_eq!(dave_count.load(Ordering::Relaxed), 1);

    // But, the filter should not be re-evaluated for the new "charlie" span
    // when it is re-entered.
    charlie2.in_scope(|| span!(Level::TRACE, "dave").in_scope(|| {}));
    assert_eq!(charlie_count.load(Ordering::Relaxed), 2);
    assert_eq!(dave_count.load(Ordering::Relaxed), 2);
}