First cut of pulling out the relevant parts of my original game to make a little framework.

tests/textures.cpp

@@ -0,0 +1,43 @@
+#include <catch2/catch_test_macros.hpp>
+#include <fmt/core.h>
+#include <string>
+#include "graphics/textures.hpp"
+#include "constants.hpp"
+#include "game/components.hpp"
+
+using namespace fmt;
+
+TEST_CASE("test texture management", "[textures]") {
+  components::init();
+  textures::init();
+
+  auto spider = textures::get_sprite("rat_with_sword");
+  REQUIRE(spider.sprite != nullptr);
+  REQUIRE(spider.texture != nullptr);
+  REQUIRE(spider.frame_size.x == TEXTURE_WIDTH);
+  REQUIRE(spider.frame_size.y == TEXTURE_HEIGHT);
+
+  auto image = textures::load_image("assets/sprites/rat_with_sword.png");
+
+  size_t floor_tile = textures::get_id("floor_tile");
+  size_t gray_stone = textures::get_id("door_plain");
+
+  auto floor_ptr = textures::get_surface(floor_tile);
+  REQUIRE(floor_ptr != nullptr);
+
+  auto gray_stone_ptr = textures::get_surface(gray_stone);
+  REQUIRE(gray_stone_ptr != nullptr);
+
+  auto& light = textures::get_ambient_light();
+  REQUIRE(light.size() > 0);
+  REQUIRE(light[floor_tile] == 0);
+  REQUIRE(light[gray_stone] > 0);
+
+  auto& tiles = textures::get_map_tile_set();
+  REQUIRE(tiles.size() > 0);
+  REQUIRE(tiles[floor_tile] > 0);
+  REQUIRE(tiles[gray_stone] > 0);
+
+  auto ceiling = textures::get_ceiling(floor_tile);
+  REQUIRE(ceiling != nullptr);
+}