diff --git a/internal/proxy/proxy_test.go b/internal/proxy/proxy_test.go
index 3ac16b230c..40e0618207 100644
--- a/internal/proxy/proxy_test.go
+++ b/internal/proxy/proxy_test.go
@@ -2193,6 +2193,14 @@ func TestProxy(t *testing.T) {
 		assert.NotEqual(t, commonpb.ErrorCode_Success, resp.ErrorCode)
 	})
 
+	wg.Add(1)
+	t.Run("DropAlias fail, dd queue full", func(t *testing.T) {
+		defer wg.Done()
+		resp, err := proxy.DropAlias(ctx, &milvuspb.DropAliasRequest{})
+		assert.NoError(t, err)
+		assert.NotEqual(t, commonpb.ErrorCode_Success, resp.ErrorCode)
+	})
+
 	proxy.sched.ddQueue.setMaxTaskNum(ddParallel)
 
 	dmParallelism := proxy.sched.dmQueue.getMaxTaskNum()