diff --git a/crates/cli/src/commands/install/progress.rs b/crates/cli/src/commands/install/progress.rs
index 204b2f7..b73a2cf 100644
--- a/crates/cli/src/commands/install/progress.rs
+++ b/crates/cli/src/commands/install/progress.rs
@@ -193,8 +193,11 @@ mod tests {
 
     use super::*;
 
+    /// 测试用的输出端：一个可注入的 sink + 它收到的行。
+    type Recorder = (Arc<dyn Fn(&str) + Send + Sync>, Arc<Mutex<Vec<String>>>);
+
     /// 抓行的输出端。
-    fn recorder() -> (Arc<dyn Fn(&str) + Send + Sync>, Arc<Mutex<Vec<String>>>) {
+    fn recorder() -> Recorder {
         let lines = Arc::new(Mutex::new(Vec::new()));
         let sink_lines = Arc::clone(&lines);
         let out: Arc<dyn Fn(&str) + Send + Sync> =