Add manual routing policy for router (#15586)

sgl-model-gateway/tests/cache_aware_backward_compat_test.rs

@@ -44,6 +44,7 @@ fn test_backward_compatibility_with_empty_model_id() {
         &workers,
         &SelectWorkerInfo {
             request_text: Some("test request"),
+            ..Default::default()
         },
     );
     assert!(selected.is_some(), "Should select a worker");
@@ -102,15 +103,24 @@ fn test_mixed_model_ids() {
 
     let default_workers: Vec<Arc<dyn Worker>> =
         vec![Arc::new(worker1.clone()), Arc::new(worker3.clone())];
-    let info = SelectWorkerInfo {
-        request_text: Some("test request"),
-    };
-    let selected = policy.select_worker(&default_workers, &info);
+    let selected = policy.select_worker(
+        &default_workers,
+        &SelectWorkerInfo {
+            request_text: Some("test request"),
+            ..Default::default()
+        },
+    );
     assert!(selected.is_some(), "Should select from default workers");
 
     let llama_workers: Vec<Arc<dyn Worker>> =
         vec![Arc::new(worker2.clone()), Arc::new(worker4.clone())];
-    let selected = policy.select_worker(&llama_workers, &info);
+    let selected = policy.select_worker(
+        &llama_workers,
+        &SelectWorkerInfo {
+            request_text: Some("test request"),
+            ..Default::default()
+        },
+    );
     assert!(selected.is_some(), "Should select from llama-3 workers");
 
     let all_workers: Vec<Arc<dyn Worker>> = vec![
@@ -119,7 +129,13 @@ fn test_mixed_model_ids() {
         Arc::new(worker3.clone()),
         Arc::new(worker4.clone()),
     ];
-    let selected = policy.select_worker(&all_workers, &info);
+    let selected = policy.select_worker(
+        &all_workers,
+        &SelectWorkerInfo {
+            request_text: Some("test request"),
+            ..Default::default()
+        },
+    );
     assert!(selected.is_some(), "Should select from all workers");
 }
 
@@ -156,6 +172,7 @@ fn test_remove_worker_by_url_backward_compat() {
         &workers,
         &SelectWorkerInfo {
             request_text: Some("test"),
+            ..Default::default()
         },
     );
     assert_eq!(selected, Some(0), "Should only have worker2 left");