chore: checkpoint before Python removal

vendor/tracing-subscriber/tests/utils.rs

@@ -0,0 +1,39 @@
+#![cfg(feature = "std")]
+
+use tracing_mock::*;
+use tracing_subscriber::prelude::*;
+
+#[test]
+fn init_ext_works() {
+    let (subscriber, finished) = subscriber::mock()
+        .event(
+            expect::event()
+                .at_level(tracing::Level::INFO)
+                .with_target("init_works"),
+        )
+        .only()
+        .run_with_handle();
+
+    let _guard = subscriber.set_default();
+    tracing::info!(target: "init_works", "it worked!");
+    finished.assert_finished();
+}
+
+#[test]
+#[cfg(feature = "fmt")]
+fn builders_are_init_ext() {
+    tracing_subscriber::fmt().set_default();
+    let _ = tracing_subscriber::fmt()
+        .with_target(false)
+        .compact()
+        .try_init();
+}
+
+#[test]
+#[cfg(all(feature = "fmt", feature = "env-filter"))]
+fn layered_is_init_ext() {
+    tracing_subscriber::registry()
+        .with(tracing_subscriber::fmt::layer())
+        .with(tracing_subscriber::EnvFilter::new("foo=info"))
+        .set_default();
+}