Fixed Steam Roller AI check affecting Terrain setting effects

src/battle_ai_util.c

@@ -439,9 +439,9 @@ bool32 IsDamageMoveUnusable(u32 move, u32 battlerAtk, u32 battlerDef)
             return TRUE;
         break;
     case EFFECT_HIT_SET_REMOVE_TERRAIN:
-	if (!(gFieldStatuses & STATUS_FIELD_TERRAIN_ANY))
-	    return TRUE;
-	break;
+        if (!(gFieldStatuses & STATUS_FIELD_TERRAIN_ANY) && gMovesInfo[move].argument == ARG_TRY_REMOVE_TERRAIN_FAIL)
+            return TRUE;
+        break;
     }
 
     return FALSE;

test/battle/move_effect/hit_set_remove_terrain.c

@@ -82,3 +82,45 @@ SINGLE_BATTLE_TEST("Ice Spinner doesn't fail if there is no terrain on the field
         NOT MESSAGE("But it failed!");
     }
 }
+
+AI_SINGLE_BATTLE_TEST("Steel Roller will not be chosen by the AI if it might fail")
+{
+    u32 move;
+
+    PARAMETRIZE { move = MOVE_ELECTRIC_TERRAIN; }
+    PARAMETRIZE { move = MOVE_NONE; }
+
+    GIVEN {
+        AI_FLAGS(AI_FLAG_CHECK_BAD_MOVE | AI_FLAG_CHECK_VIABILITY | AI_FLAG_TRY_TO_FAINT);
+        PLAYER(SPECIES_WOBBUFFET);
+        OPPONENT(SPECIES_WOBBUFFET) { Moves(MOVE_STEEL_ROLLER, MOVE_ICE_SHARD); }
+    } WHEN {
+        if (move == MOVE_ELECTRIC_TERRAIN) {
+            TURN { MOVE(player, MOVE_ELECTRIC_TERRAIN); EXPECT_MOVE(opponent, MOVE_ICE_SHARD); }
+            TURN { EXPECT_MOVE(opponent, MOVE_STEEL_ROLLER); }
+        } else {
+            TURN { EXPECT_MOVE(opponent, MOVE_ICE_SHARD); }
+        }
+    }
+}
+
+AI_SINGLE_BATTLE_TEST("Ice Spinner can be chosen by the AI regardless if there is a terrain or not")
+{
+    u32 move;
+
+    PARAMETRIZE { move = MOVE_ELECTRIC_TERRAIN; }
+    PARAMETRIZE { move = MOVE_NONE; }
+
+    GIVEN {
+        AI_FLAGS(AI_FLAG_CHECK_BAD_MOVE | AI_FLAG_CHECK_VIABILITY | AI_FLAG_TRY_TO_FAINT);
+        PLAYER(SPECIES_WOBBUFFET);
+        OPPONENT(SPECIES_WOBBUFFET) { Moves(MOVE_ICE_SPINNER, MOVE_ICE_SHARD); }
+    } WHEN {
+        if (move == MOVE_ELECTRIC_TERRAIN) {
+            TURN { MOVE(player, MOVE_ELECTRIC_TERRAIN); EXPECT_MOVE(opponent, MOVE_ICE_SPINNER); }
+            TURN { EXPECT_MOVE(opponent, MOVE_ICE_SPINNER); }
+        } else {
+            TURN { EXPECT_MOVE(opponent, MOVE_ICE_SPINNER); }
+        }
+    }
+}