add test reproducing #2587, #2436, and #2411

tracing-core/tests/local_dispatch_before_init.rs

@@ -0,0 +1,44 @@
+mod common;
+
+use common::*;
+use tracing_core::{subscriber::NoSubscriber, dispatcher::{Dispatch, self}};
+
+/// This test reproduces the following issues:
+/// - https://github.com/tokio-rs/tracing/issues/2587
+/// - https://github.com/tokio-rs/tracing/issues/2411
+/// - https://github.com/tokio-rs/tracing/issues/2436
+#[test]
+fn local_dispatch_before_init() {
+ dispatcher::get_default(|current| assert!(current.is::<NoSubscriber>()));
+
+ // Temporarily override the default dispatcher with a scoped dispatcher.
+ //
+ // This will suppress the "SCOPED_COUNT" optimization and cause threads to
+ // attempt to cache the global default after the scoped dispatcher has been
+ // unset.
+ #[cfg(feature = "std")] {
+ dispatcher::with_default(&Dispatch::new(TestSubscriberB), || {
+ dispatcher::get_default(|current| {
+ assert!(
+ current.is::<TestSubscriberB>(),
+ "overriden subscriber not set; current: {:?}",
+ current,
+ );
+ })
+ })
+ }
+
+ dispatcher::get_default(|current| assert!(current.is::<NoSubscriber>()));
+
+ dispatcher::set_global_default(Dispatch::new(TestSubscriberA))
+ .expect("set global dispatch failed");
+
+ dispatcher::get_default(|current| {
+ assert!(
+ current.is::<TestSubscriberA>(),
+ "default subscriber not set; current: {:?}",
+ current,
+ );
+ });
+
+}