From 0342f6742d463bdd9c8f6d4103952ae595d57523 Mon Sep 17 00:00:00 2001
From: Adrian Wannenmacher <tfld@tfld.dev>
Date: Tue, 10 Mar 2026 19:19:05 +0100
Subject: [PATCH] move game rule cloning to game constructor

The rules not changing after a game has started is a invariant of the
`Game` model, not the `Session` model. As such, it should enforce it
itself, instead of relying on its users.
---
 models/game.js         |  2 +-
 models/game.test.js    | 12 ++++++++++++
 models/session.js      |  2 +-
 models/session.test.js | 11 -----------
 4 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/models/game.js b/models/game.js
index 14a4359..0e4ae28 100644
--- a/models/game.js
+++ b/models/game.js
@@ -59,7 +59,7 @@ export default class Game extends EventTarget {
     super();
     if (value === undefined || value instanceof GameRules) {
       if (value instanceof GameRules)
-        this.#rules = value;
+        this.#rules = new GameRules(value);
 
       this.#currentRound = new Round(
         this.#rules.raisingLimit(0), this.#rules.raisingLimit(0));
diff --git a/models/game.test.js b/models/game.test.js
index f85a4a3..b3ee4fd 100644
--- a/models/game.test.js
+++ b/models/game.test.js
@@ -53,6 +53,18 @@ export default function() {
       );
     });
 
+    QUnit.test("rules stay static after construction", function(assert) {
+      let rules = new GameRules();
+      rules.goal = 15;
+
+      let game = new Game(rules);
+      assert.strictEqual(game.rules.goal, 15, "correct goal");
+
+      rules.goal = 17;
+      assert.strictEqual(game.rules.goal, 15, "games rules didn't change");
+      assert.notStrictEqual(game.rules.goal, rules.goal, "goals are different");
+    });
+
     QUnit.test("single round played", function(assert) {
       let game = new Game();
       game.currentRound.winner = Team.We;
diff --git a/models/session.js b/models/session.js
index f101a5a..1a250f5 100644
--- a/models/session.js
+++ b/models/session.js
@@ -130,7 +130,7 @@ export default class Session extends EventTarget {
   /** Add another round if there is no current one. */
   anotherGame() {
     if (this.#currentGame === null) {
-      this.#currentGame = new Game(new GameRules(this.#rules));
+      this.#currentGame = new Game(this.#rules);
       this.#currentGame.addEventListener(
         Game.EVENT_CHANGE, this.#boundHandleGameChange);
       this.#changed();
diff --git a/models/session.test.js b/models/session.test.js
index b444e6f..b727450 100644
--- a/models/session.test.js
+++ b/models/session.test.js
@@ -60,17 +60,6 @@ export default function() {
       assert.notStrictEqual(session.currentGame, null, "game in progress");
     });
 
-    QUnit.test("session rule change doesn't affect games", function(assert) {
-      let session = new Session();
-      session.anotherGame();
-      session.rules.goal = 7;
-      assert.notStrictEqual(
-        session.currentGame.rules.goal,
-        session.rules.goal,
-        "game rules have been copied",
-      );
-    });
-
     QUnit.test("single game finished", function(assert) {
       let session = new Session();
       session.anotherGame();