test(config): add custom commands order test (#1536)

src/config.rs

@@ -1892,4 +1892,24 @@ mod test {
         config.opt = CommandLineArgs::parse_from(["topgrade", "--remote-host-limit", "other_hostname"]);
         assert!(!config.should_execute_remote(Ok("hostname".to_string()), "user@remote_hostname"));
     }
+
+    /// Ensure that custom commands are stored in insertion order.
+    #[test]
+    fn test_custom_commands_order() {
+        let toml_str = r#"
+[commands]
+z = "cmd_z"
+y = "cmd_y"
+x = "cmd_x"
+"#;
+        let order: Vec<_> = toml::from_str::<ConfigFile>(toml_str)
+            .expect("toml parse error")
+            .commands
+            .expect("commands field missing")
+            .keys()
+            .cloned()
+            .collect();
+
+        assert_eq!(order, vec!["z", "y", "x"]);
+    }
 }