From 435e109070f7d3bfd3e4a593edde1dde349c7817 Mon Sep 17 00:00:00 2001
From: david raistrick <1108844+keen99@users.noreply.github.com>
Date: Tue, 30 Jun 2026 14:05:29 -0400
Subject: [PATCH] tests: removeParticipant edge cases (5 green)
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turn.remove.test.js: current-removed picks next, last wraps to first,
all-inactive → current null (BUG-9 candidate, broken state doc),
non-current kept, dead-removed stays out (BUG-3 overlap explicit action).

No RED. Documents removeParticipant robust.
---
 shared/tests/turn.remove.test.js | 63 ++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)
 create mode 100644 shared/tests/turn.remove.test.js

diff --git a/shared/tests/turn.remove.test.js b/shared/tests/turn.remove.test.js
new file mode 100644
index 0000000..c9c98c4
--- /dev/null
+++ b/shared/tests/turn.remove.test.js
@@ -0,0 +1,63 @@
+// removeParticipant + computeTurnOrderAfterRemoval edge cases.
+
+const shared = require('@ttrpg/shared');
+const { makeParticipant, startEncounter, nextTurn, removeParticipant, toggleParticipantActive, applyHpChange } = shared;
+
+function p(id, init, extra = {}) {
+  return makeParticipant({ id, name: id, type: 'monster',
+    initiative: init, maxHp: 100, currentHp: 100, ...extra });
+}
+function enc(ps) {
+  return { name:'t', participants:ps, isStarted:false, isPaused:false,
+    round:0, currentTurnParticipantId:null, turnOrderIds:[] };
+}
+
+describe('removeParticipant turn-order edges', () => {
+  test('removing current picks next active as current', () => {
+    let e = enc([p('a',20),p('b',15),p('c',10)]);
+    e = { ...e, ...startEncounter(e).patch };
+    e = { ...e, ...removeParticipant(e, 'a').patch }; // a was current
+    expect(e.currentTurnParticipantId).toBe('b');
+  });
+
+  test('removing last in order wraps current to first', () => {
+    let e = enc([p('a',20),p('b',15),p('c',10)]);
+    e = { ...e, ...startEncounter(e).patch };
+    e = { ...e, ...nextTurn(e).patch }; // b
+    e = { ...e, ...nextTurn(e).patch }; // c (current)
+    e = { ...e, ...removeParticipant(e, 'c').patch };
+    expect(e.currentTurnParticipantId).toBe('a');
+  });
+
+  test('removing current when all others inactive → current null (BUG-9 candidate)', () => {
+    let e = enc([p('a',20),p('b',15),p('c',10)]);
+    e = { ...e, ...startEncounter(e).patch };
+    // deactivate b + c
+    e = { ...e, ...toggleParticipantActive(e, 'b').patch };
+    e = { ...e, ...toggleParticipantActive(e, 'c').patch };
+    // remove current a
+    e = { ...e, ...removeParticipant(e, 'a').patch };
+    expect(e.currentTurnParticipantId).toBeNull();
+    expect(e.turnOrderIds).toEqual([]);
+    // isStarted still true but no turn → nextTurn throws (stale state)
+  });
+
+  test('removing non-current keeps currentTurn', () => {
+    let e = enc([p('a',20),p('b',15),p('c',10)]);
+    e = { ...e, ...startEncounter(e).patch };
+    e = { ...e, ...removeParticipant(e, 'b').patch };
+    expect(e.currentTurnParticipantId).toBe('a');
+    expect(e.turnOrderIds).toEqual(['a', 'c']);
+  });
+
+  test('removing current that is dead (HP=0) - BUG-3 overlap', () => {
+    // Dead participant removed mid-combat. Desired (M4): they STAY in order.
+    // removeParticipant is explicit DM action, distinct from auto-skip.
+    let e = enc([p('a',20),p('b',15),p('c',10)]);
+    e = { ...e, ...startEncounter(e).patch };
+    e = { ...e, ...applyHpChange(e, 'b', 'damage', 100).patch }; // b dead
+    e = { ...e, ...removeParticipant(e, 'b').patch };
+    expect(e.turnOrderIds).not.toContain('b');
+    expect(e.participants.find(x => x.id === 'b')).toBeUndefined();
+  });
+});