test(rust/client): add unit test for DNS and network change notifiers (#6635)

Part of a yak shave towards removing Tauri.

---------

Signed-off-by: Reactor Scram <ReactorScram@users.noreply.github.com>

rust/bin-shared/src/network_changes.rs

@@ -10,3 +10,30 @@ mod imp;
 
 #[cfg(any(target_os = "windows", target_os = "linux"))]
 pub use imp::{new_dns_notifier, new_network_notifier};
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::platform::DnsControlMethod;
+
+    /// Smoke test for the DNS and network change notifiers
+    ///
+    /// Turn them on, wait a second, turn them off.
+    /// This tests that the threads quit gracefully when we call `close`, and they don't crash on startup.
+    #[tokio::test]
+    async fn notifiers() {
+        let tokio_handle = tokio::runtime::Handle::current();
+
+        let mut dns = new_dns_notifier(tokio_handle.clone(), DnsControlMethod::default())
+            .await
+            .unwrap();
+        let mut net = new_network_notifier(tokio_handle, DnsControlMethod::default())
+            .await
+            .unwrap();
+
+        tokio::time::sleep(std::time::Duration::from_secs(1)).await;
+
+        dns.close().unwrap();
+        net.close().unwrap();
+    }
+}