Add: Mock sprite cache intialization.

This fills up the sprite cache with SPR_OPENTTD_BASE + OPENTTD_SPRITE_COUNT zero-size sprites, to
allow GetSpriteSize() calls to continue from unit-tests.

src/spritecache.cpp

@@ -102,7 +102,6 @@ static uint _allocated_sprite_cache_size = 0;
 static int _compact_cache_counter;
 
 static void CompactSpriteCache();
-static void *AllocSprite(size_t mem_req);
 
 /**
  * Skip the given amount of sprite graphics data.
@@ -831,7 +830,7 @@ static void DeleteEntryFromSpriteCache()
 	DeleteEntryFromSpriteCache(best);
 }
 
-static void *AllocSprite(size_t mem_req)
+void *AllocSprite(size_t mem_req)
 {
 	mem_req += sizeof(MemBlock);
 

src/spritecache_internal.h

@@ -36,6 +36,7 @@ static inline bool IsMapgenSpriteID(SpriteID sprite)
 	return IsInsideMM(sprite, SPR_MAPGEN_BEGIN, SPR_MAPGEN_END);
 }
 
+void *AllocSprite(size_t mem_req);
 SpriteCache *AllocateSpriteCache(uint index);
 
 #endif /* SPRITECACHE_INTERNAL_H */

src/tests/CMakeLists.txt

@@ -2,6 +2,8 @@ add_test_files(
     landscape_partial_pixel_z.cpp
     math_func.cpp
     mock_fontcache.h
+    mock_spritecache.cpp
+    mock_spritecache.h
     string_func.cpp
     strings_func.cpp
     test_main.cpp

src/tests/mock_spritecache.cpp

@@ -0,0 +1,49 @@
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file mock_spritecache.cpp Mock sprite cache implementation. */
+
+#include "../stdafx.h"
+
+#include "../blitter/factory.hpp"
+#include "../core/math_func.hpp"
+#include "../spritecache.h"
+#include "../spritecache_internal.h"
+#include "../table/sprites.h"
+
+static bool MockLoadNextSprite(int load_index)
+{
+	static Sprite *sprite = (Sprite *)AllocSprite(sizeof(*sprite));
+
+	bool is_mapgen = IsMapgenSpriteID(load_index);
+
+	SpriteCache *sc = AllocateSpriteCache(load_index);
+	sc->file = nullptr;
+	sc->file_pos = 0;
+	sc->ptr = sprite;
+	sc->lru = 0;
+	sc->id = 0;
+	sc->type = is_mapgen ? SpriteType::MapGen : SpriteType::Normal;
+	sc->warned = false;
+	sc->control_flags = 0;
+
+	/* Fill with empty sprites up until the default sprite count. */
+	return (uint)load_index < SPR_OPENTTD_BASE + OPENTTD_SPRITE_COUNT;
+}
+
+void MockGfxLoadSprites()
+{
+	/* Force blitter 'null'. This is necessary for GfxInitSpriteMem() to function. */
+	BlitterFactory::SelectBlitter("null");
+
+	GfxInitSpriteMem();
+
+	int load_index = 0;
+	while (MockLoadNextSprite(load_index)) {
+		load_index++;
+	}
+}

src/tests/mock_spritecache.h

@@ -0,0 +1,15 @@
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file mock_spritecache.h Mock sprite cache definition. */
+
+#ifndef MOCK_SPRITECACHE_H
+#define MOCK_SPRITECACHE_H
+
+void MockGfxLoadSprites();
+
+#endif /* MOCK_SPRITECACHE_H */