From 5207be5823364a0107370ea8834f620a55131134 Mon Sep 17 00:00:00 2001
From: Evandro Abu Kamel <evandro.abukamel@gmail.com>
Date: Wed, 25 Nov 2020 14:33:48 -0300
Subject: [PATCH] fix(set-stage): setStage event for Stage.NULL makes player
 active. (closes #848) (#849)

* Fixing setStage to make players set on Stage.NULL active.

* Update src/core/turn-order.test.ts

Co-authored-by: Chris Swithinbank <swithinbank@gmail.com>

* Update src/core/turn-order.test.ts

Co-authored-by: Chris Swithinbank <swithinbank@gmail.com>

Co-authored-by: Evandro Abu Kamel <evandro.costa@maxmilhas.com.br>
Co-authored-by: Chris Swithinbank <swithinbank@gmail.com>
---
 src/core/flow.ts            |  8 +++---
 src/core/turn-order.test.ts | 49 +++++++++++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+), 3 deletions(-)

diff --git a/src/core/flow.ts b/src/core/flow.ts
index a645ba2a7..b2e48f7fc 100644
--- a/src/core/flow.ts
+++ b/src/core/flow.ts
@@ -353,7 +353,7 @@ export function Flow({
   }
 
   function UpdateStage(state: State, { arg, playerID }): State {
-    if (typeof arg === 'string') {
+    if (typeof arg === 'string' || arg === Stage.NULL) {
       arg = { stage: arg };
     }
 
@@ -364,7 +364,8 @@ export function Flow({
       _activePlayersNumMoves,
     } = ctx;
 
-    if (arg.stage) {
+    // Checking if stage is valid, even Stage.NULL
+    if (arg.stage !== undefined) {
       if (activePlayers === null) {
         activePlayers = {};
       }
@@ -562,7 +563,8 @@ export function Flow({
       if (stage && stage.next) arg = stage.next;
     }
 
-    if (next && arg) {
+    // Checking if arg is a valid stage, even Stage.NULL
+    if (next && arg !== undefined) {
       next.push({ fn: UpdateStage, arg, playerID });
     }
 
diff --git a/src/core/turn-order.test.ts b/src/core/turn-order.test.ts
index 9a6f42f0d..d95ec9aaa 100644
--- a/src/core/turn-order.test.ts
+++ b/src/core/turn-order.test.ts
@@ -451,6 +451,55 @@ describe('setActivePlayers', () => {
     expect(state.ctx.activePlayers).toBeNull();
   });
 
+  test('set stages to Stage.NULL', () => {
+    const game = {
+      moves: {
+        A: G => G,
+        B: (G, ctx) => {
+          ctx.events.setActivePlayers({
+            moveLimit: 1,
+            currentPlayer: 'start',
+          });
+          return G;
+        },
+      },
+      turn: {
+        activePlayers: {
+          currentPlayer: {
+            stage: 'start',
+          },
+          others: Stage.NULL,
+        },
+        stages: {
+          start: {
+            moves: {
+              S: (G, ctx) => {
+                ctx.events.setStage(Stage.NULL);
+                return G;
+              },
+            },
+          },
+        },
+      },
+    };
+    const reducer = CreateGameReducer({ game });
+    let state = InitializeGame({ game, numPlayers: 3 });
+
+    expect(state.ctx.currentPlayer).toBe('0');
+    expect(Object.keys(state.ctx.activePlayers)).toEqual(['0', '1', '2']);
+    expect(state.ctx.activePlayers['0']).toEqual('start');
+    expect(state.ctx.activePlayers['1']).toEqual(Stage.NULL);
+    expect(state.ctx.activePlayers['2']).toEqual(Stage.NULL);
+
+    state = reducer(state, makeMove('S', null, '0'));
+    expect(Object.keys(state.ctx.activePlayers)).toEqual(['0', '1', '2']);
+    expect(state.ctx.activePlayers['0']).toEqual(Stage.NULL);
+
+    state = reducer(state, makeMove('B', null, '0'));
+    expect(Object.keys(state.ctx.activePlayers)).toEqual(['0']);
+    expect(state.ctx.activePlayers['0']).toEqual('start');
+  });
+
   describe('reset behavior', () => {
     test('start of turn', () => {
       const game = {