test: improve testability of input events

tests/ui_snapshot.rs

@@ -12,7 +12,7 @@ fn render_list_into_buffer(
     width: u16,
     height: u16,
 ) -> Buffer {
-    let backend = TestBackend::new(width.into(), height.into());
+    let backend = TestBackend::new(width, height);
     let mut terminal = Terminal::new(backend).expect("create terminal");
 
     let lines_vec: Vec<ListItem> = lines
@@ -45,8 +45,8 @@ fn render_list_into_buffer(
 
     // Extract the underlying backend buffer (clone to own it)
     let backend = terminal.backend();
-    let buf = backend.buffer().clone();
-    buf
+
+    backend.buffer().clone()
 }
 
 #[test]