[Bugfix] Events should be undoable

src/core/reducer.test.ts

@@ -327,8 +327,17 @@ describe('undo / redo', () => {
         G.roll = ctx.random.D6();
       },
     },
+    turn: {
+      stages: {
+        special: {},
+      },
+    },
   };
 
+  beforeEach(() => {
+    jest.clearAllMocks();
+  });
+
   const reducer = CreateGameReducer({ game });
 
   const initialState = InitializeGame({ game });
@@ -341,7 +350,7 @@ describe('undo / redo', () => {
     expect(state._undo[1].ctx.random).toBeUndefined();
   });
 
-  test('undo restores previous state', () => {
+  test('undo restores previous state after move', () => {
     let state = reducer(initialState, makeMove('move', 'A', '0'));
     const { G, ctx, plugins } = state;
     state = reducer(state, makeMove('roll', null, '0'));
@@ -351,6 +360,20 @@ describe('undo / redo', () => {
     expect(state.plugins).toEqual(plugins);
   });
 
+  test('undo restores previous state after event', () => {
+    let state = reducer(initialState, gameEvent('setStage', 'special', '0'));
+    const { G, ctx, plugins } = state;
+    state = reducer(state, gameEvent('endStage', undefined, '0'));
+    expect(error).not.toBeCalled();
+    // Make sure we actually modified the stage.
+    expect(state.ctx.activePlayers).not.toEqual(ctx.activePlayers);
+    state = reducer(state, undo());
+    expect(error).not.toBeCalled();
+    expect(state.G).toEqual(G);
+    expect(state.ctx).toEqual(ctx);
+    expect(state.plugins).toEqual(plugins);
+  });
+
   test('redo restores undone state', () => {
     let state = initialState;
     // Make two moves.

src/core/reducer.ts

@@ -314,14 +314,16 @@ export function CreateGameReducer({
           return state;
         }
 
-        // Only allow undoable moves to be undone.
-        const lastMove: Move = game.flow.getMove(
-          restore.ctx,
-          last.moveType,
-          last.playerID
-        );
-        if (!CanUndoMove(state.G, state.ctx, lastMove)) {
-          return state;
+        // If undoing a move, check it is undoable.
+        if (last.moveType) {
+          const lastMove: Move = game.flow.getMove(
+            restore.ctx,
+            last.moveType,
+            last.playerID
+          );
+          if (!CanUndoMove(state.G, state.ctx, lastMove)) {
+            return state;
+          }
         }
 
         state = initializeDeltalog(state, action);