vendor/tracing/tests/filter_caching_is_lexically_scoped.rs

   1 // Tests that depend on a count of the number of times their filter is evaluated
   2 // can't exist in the same file with other tests that add subscribers to the
   3 // registry. The registry was changed so that each time a new dispatcher is
   4 // added all filters are re-evaluated. The tests being run only in separate
   5 // threads with shared global state lets them interfere with each other
   6
   7 #[cfg(not(feature = "std"))]
   8 extern crate std;
   9
  10 use tracing::{span, Level};
  11 use tracing_mock::*;
  12
  13 use std::sync::{
  14     atomic::{AtomicUsize, Ordering},
  15     Arc,
  16 };
  17
  18 #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
  19 #[test]
  20 fn filter_caching_is_lexically_scoped() {
  21     pub fn my_great_function() -> bool {
  22         span!(Level::TRACE, "emily").in_scope(|| true)
  23     }
  24
  25     pub fn my_other_function() -> bool {
  26         span!(Level::TRACE, "frank").in_scope(|| true)
  27     }
  28
  29     let count = Arc::new(AtomicUsize::new(0));
  30     let count2 = count.clone();
  31
  32     let subscriber = subscriber::mock()
  33         .with_filter(move |meta| match meta.name() {
  34             "emily" | "frank" => {
  35                 count2.fetch_add(1, Ordering::Relaxed);
  36                 true
  37             }
  38             _ => false,
  39         })
  40         .run();
  41
  42     // Since this test is in its own file anyway, we can do this. Thus, this
  43     // test will work even with no-std.
  44     tracing::subscriber::set_global_default(subscriber).unwrap();
  45
  46     // Call the function once. The filter should be re-evaluated.
  47     assert!(my_great_function());
  48     assert_eq!(count.load(Ordering::Relaxed), 1);
  49
  50     // Call the function again. The cached result should be used.
  51     assert!(my_great_function());
  52     assert_eq!(count.load(Ordering::Relaxed), 1);
  53
  54     assert!(my_other_function());
  55     assert_eq!(count.load(Ordering::Relaxed), 2);
  56
  57     assert!(my_great_function());
  58     assert_eq!(count.load(Ordering::Relaxed), 2);
  59
  60     assert!(my_other_function());
  61     assert_eq!(count.load(Ordering::Relaxed), 2);
  62
  63     assert!(my_great_function());
  64     assert_eq!(count.load(Ordering::Relaxed), 2);
  65 }