test: add unit test for SplitQueueRing flag and event accessors

Signed-off-by: Nelson Wong <[email protected]>

Author: wongnelson

virtio-queue/src/mock.rs

@@ -581,3 +581,68 @@ impl<'a, M: GuestMemory> MockSplitQueue<'a, M> {
         Ok(())
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use vm_memory::{GuestAddress, GuestMemoryMmap};
+
+    // SplitQueueRing load/store API coverage for AvailRing (u16)
+    #[test]
+    fn test_avail_ring_load_store() {
+        let mem = &GuestMemoryMmap::<()>::from_ranges(&[(GuestAddress(0), 0x10000)]).unwrap();
+        let len = 8u16;
+        let base = GuestAddress(0x1000);
+        let ring: AvailRing<_> = AvailRing::new(mem, base, len);
+
+        // flags
+        ring.store_flags(0x55aa);
+        assert_eq!(ring.load_flags(), 0x55aa);
+
+        // idx
+        ring.store_idx(7);
+        assert_eq!(ring.load_idx(), 7);
+
+        // ring entry
+        ring.store_ring_entry(3, 0xbeef).unwrap();
+        assert_eq!(ring.load_ring_entry(3).unwrap(), 0xbeef);
+
+        // event field
+        ring.store_event(0x1234);
+        assert_eq!(ring.load_event(), 0x1234);
+
+        // out-of-bounds must error
+        assert!(matches!(
+            ring.store_ring_entry(len as usize, 0).unwrap_err(),
+            MockError::InvalidIndex
+        ));
+    }
+
+    // SplitQueueRing load/store API coverage for UsedRing (VirtqUsedElem)
+    #[test]
+    fn test_used_ring_load_store() {
+        let mem = &GuestMemoryMmap::<()>::from_ranges(&[(GuestAddress(0), 0x20000)]).unwrap();
+        let len = 8u16;
+        let base = GuestAddress(0x3000);
+        let ring: UsedRing<_> = UsedRing::new(mem, base, len);
+
+        // flags
+        ring.store_flags(0xccdd);
+        assert_eq!(ring.load_flags(), 0xccdd);
+
+        // idx
+        ring.store_idx(2);
+        assert_eq!(ring.load_idx(), 2);
+
+        // ring entry
+        let elem = VirtqUsedElem::new(42, 0x1000);
+        ring.store_ring_entry(0, elem).unwrap();
+        let read = ring.load_ring_entry(0).unwrap();
+        assert_eq!(read.id(), 42);
+        assert_eq!(read.len(), 0x1000);
+
+        // event field
+        ring.store_event(0xdead);
+        assert_eq!(ring.load_event(), 0xdead);
+    }
+}