From 1a7166c2bb86c867d1e7c5b607d0460208f15ada Mon Sep 17 00:00:00 2001
From: DizzyEggg <jajkodizzy@wp.pl>
Date: Sat, 23 Dec 2023 00:27:40 +0100
Subject: [PATCH] Tests do not allow to use SEND_OUT if the chosen mon is
 fainted (#3752)

* Tests dont allow to send out pokemon with 0 hp

* remove test test

* handle in-game 0 hp sent out

---------

Co-authored-by: Bassoonian <iasperbassoonian@gmail.com>
---
 include/test_runner.h        |  2 ++
 src/battle_script_commands.c | 29 +++++++++++++++++++++++++++++
 test/test_runner_battle.c    |  6 ++++++
 3 files changed, 37 insertions(+)

diff --git a/include/test_runner.h b/include/test_runner.h
index e0df88b0a6..248a0463e5 100644
--- a/include/test_runner.h
+++ b/include/test_runner.h
@@ -19,6 +19,7 @@ void TestRunner_Battle_CheckSwitch(u32 battlerId, u32 partyIndex);
 void TestRunner_Battle_CheckAiMoveScores(u32 battlerId);
 void TestRunner_Battle_AISetScore(const char *file, u32 line, u32 battlerId, u32 moveIndex, s32 score);
 void TestRunner_Battle_AIAdjustScore(const char *file, u32 line, u32 battlerId, u32 moveIndex, s32 score);
+void TestRunner_Battle_InvalidNoHPMon(u32 battlerId, u32 partyIndex);
 
 void TestRunner_Battle_CheckBattleRecordActionType(u32 battlerId, u32 recordIndex, u32 actionType);
 
@@ -38,6 +39,7 @@ u32 TestRunner_Battle_GetForcedAbility(u32 side, u32 partyIndex);
 #define TestRunner_Battle_CheckAiMoveScores(...) (void)0
 #define TestRunner_Battle_AISetScore(...) (void)0
 #define TestRunner_Battle_AIAdjustScore(...) (void)0
+#define TestRunner_Battle_InvalidNoHPMon(...) (void)0
 
 #define TestRunner_Battle_CheckBattleRecordActionType(...) (void)0
 
diff --git a/src/battle_script_commands.c b/src/battle_script_commands.c
index 0114bc014a..34a3da0857 100644
--- a/src/battle_script_commands.c
+++ b/src/battle_script_commands.c
@@ -6166,6 +6166,35 @@ static void Cmd_switchindataupdate(void)
     for (i = 0; i < sizeof(struct BattlePokemon); i++)
         monData[i] = gBattleResources->bufferB[battler][4 + i];
 
+    // Edge case: the sent out pokemon has 0 HP. This should never happen.
+    if (gBattleMons[battler].hp == 0)
+    {
+        // If it's a test, mark it as invalid.
+        if (gTestRunnerEnabled)
+        {
+            TestRunner_Battle_InvalidNoHPMon(battler, gBattlerPartyIndexes[battler]);
+        }
+        // Handle in-game scenario.
+        else
+        {
+            struct Pokemon *party = GetBattlerParty(battler);
+            // Find the first possible replacement for the not valid pokemon.
+            for (i = 0; i < PARTY_SIZE; i++)
+            {
+                if (IsValidForBattle(&party[i]))
+                    break;
+            }
+            // There is valid replacement.
+            if (i != PARTY_SIZE)
+            {
+                gBattlerPartyIndexes[battler] = gBattleStruct->monToSwitchIntoId[battler] = i;
+                BtlController_EmitGetMonData(battler, BUFFER_A, REQUEST_ALL_BATTLE, gBitTable[gBattlerPartyIndexes[battler]]);
+                MarkBattlerForControllerExec(battler);
+                return;
+            }
+        }
+    }
+
     gBattleMons[battler].type1 = gSpeciesInfo[gBattleMons[battler].species].types[0];
     gBattleMons[battler].type2 = gSpeciesInfo[gBattleMons[battler].species].types[1];
     gBattleMons[battler].type3 = TYPE_MYSTERY;
diff --git a/test/test_runner_battle.c b/test/test_runner_battle.c
index 5e42057955..1528a3ccf9 100644
--- a/test/test_runner_battle.c
+++ b/test/test_runner_battle.c
@@ -881,6 +881,12 @@ void TestRunner_Battle_CheckSwitch(u32 battlerId, u32 partyIndex)
     DATA.aiActionsPlayed[battlerId]++;
 }
 
+void TestRunner_Battle_InvalidNoHPMon(u32 battlerId, u32 partyIndex)
+{
+    Test_ExitWithResult(TEST_RESULT_INVALID, "%s: INVALID: %s trying to send out a mon(id: %d) with 0 HP.",
+                        gTestRunnerState.test->filename, BattlerIdentifier(battlerId), gBattlerPartyIndexes[battlerId]);
+}
+
 static bool32 CheckComparision(s32 val1, s32 val2, u32 cmp)
 {
     switch (cmp)