Add integration tests based on VM

src/tui/state.rs

@@ -269,6 +269,15 @@ impl UiState {
     }
 
     pub fn select_peer_index(&mut self, peer_index: usize) -> bool {
+        if !self.highlight_peer_index(peer_index) {
+            return false;
+        }
+        self.screen = Screen::ClientDetails;
+        true
+    }
+
+    /// Move the client-list highlight without changing the active screen.
+    pub fn highlight_peer_index(&mut self, peer_index: usize) -> bool {
         let Some(client) = self.view.as_ref().and_then(|view| {
             view.clients
                 .iter()
@@ -278,7 +287,6 @@ impl UiState {
         };
         self.selected_peer_index = Some(peer_index);
         self.selected_identity = client.identity;
-        self.screen = Screen::ClientDetails;
         true
     }