chore: checkpoint before Python removal

vendor/tracing-core/tests/global_dispatch.rs

@@ -0,0 +1,34 @@
+mod common;
+
+use common::*;
+use tracing_core::dispatcher::*;
+#[test]
+fn global_dispatch() {
+    set_global_default(Dispatch::new(TestSubscriberA)).expect("global dispatch set failed");
+    get_default(|current| {
+        assert!(
+            current.is::<TestSubscriberA>(),
+            "global dispatch get failed"
+        )
+    });
+
+    #[cfg(feature = "std")]
+    with_default(&Dispatch::new(TestSubscriberB), || {
+        get_default(|current| {
+            assert!(
+                current.is::<TestSubscriberB>(),
+                "thread-local override of global dispatch failed"
+            )
+        });
+    });
+
+    get_default(|current| {
+        assert!(
+            current.is::<TestSubscriberA>(),
+            "reset to global override failed"
+        )
+    });
+
+    set_global_default(Dispatch::new(TestSubscriberA))
+        .expect_err("double global dispatch set succeeded");
+}