chore: checkpoint before Python removal

vendor/tokio/tests/process_change_of_runtime.rs

@@ -0,0 +1,34 @@
+#![cfg(feature = "process")]
+#![warn(rust_2018_idioms)]
+// This tests test the behavior of `process::Command::spawn` when it is used
+// outside runtime, and when `process::Child::wait ` is used in a different
+// runtime from which `process::Command::spawn` is used.
+#![cfg(all(unix, not(target_os = "freebsd"), not(miri)))] // Miri cannot run system commands
+
+use std::process::Stdio;
+use tokio::{process::Command, runtime::Runtime};
+
+#[test]
+fn process_spawned_and_wait_in_different_runtime() {
+    let mut child = Runtime::new().unwrap().block_on(async {
+        Command::new("true")
+            .stdin(Stdio::piped())
+            .stdout(Stdio::null())
+            .spawn()
+            .unwrap()
+    });
+    Runtime::new().unwrap().block_on(async {
+        let _ = child.wait().await.unwrap();
+    });
+}
+
+#[test]
+#[should_panic(
+    expected = "there is no reactor running, must be called from the context of a Tokio 1.x runtime"
+)]
+fn process_spawned_outside_runtime() {
+    let _ = Command::new("true")
+        .stdin(Stdio::piped())
+        .stdout(Stdio::null())
+        .spawn();
+}