diff --git a/tests/testDataPack.cpp b/tests/testDataPack.cpp
new file mode 100644
index 0000000..e71e0f3
--- /dev/null
+++ b/tests/testDataPack.cpp
@@ -0,0 +1,160 @@
+#include "testHarness.h"
+#include "vf/DataPack.h"
+
+#include <cstdio>
+#include <string>
+
+using namespace vf;
+
+namespace {
+
+ResourceId id(const std::string& text) {
+    ResourceId parsed;
+    ResourceId::parse(text, "voxelforge", parsed);
+    return parsed;
+}
+
+const char* const redstoneTorchShaped = R"json({
+  "type": "craftingShaped",
+  "pattern": ["R", "S"],
+  "key": {"R": "voxelforge:redstone_dust", "S": "voxelforge:stick"},
+  "mirror": false,
+  "result": {"item": "voxelforge:redstone_torch", "count": 4}
+})json";
+
+const char* const redstoneTorchRicher = R"json({
+  "type": "craftingShaped",
+  "pattern": ["R", "S"],
+  "key": {"R": "voxelforge:redstone_dust", "S": "voxelforge:stick"},
+  "mirror": false,
+  "result": {"item": "voxelforge:redstone_torch", "count": 8}
+})json";
+
+const char* const appleBread = R"json({
+  "type": "craftingShapeless",
+  "ingredients": ["voxelforge:apple", "voxelforge:apple"],
+  "result": {"item": "voxelforge:bread", "count": 1}
+})json";
+
+const char* const sandSmelting = R"json({
+  "type": "smelting",
+  "ingredient": "voxelforge:sand",
+  "seconds": 12.5,
+  "experience": 0.7,
+  "result": {"item": "voxelforge:sandstone", "count": 1}
+})json";
+
+const char* const starterChest = R"json({
+  "pools": [
+    {
+      "rolls": 1,
+      "entries": [
+        {"item": "voxelforge:bread", "weight": 1, "count": 2}
+      ]
+    },
+    {
+      "rolls": 1,
+      "entries": [
+        {"item": "voxelforge:diamond_gem", "weight": 1, "count": 1,
+         "conditions": ["playerKill"], "functions": ["lootingBonus"]}
+      ]
+    }
+  ]
+})json";
+
+DataPack basePack() {
+    DataPackMeta meta;
+    meta.name = "base";
+    DataPack pack(meta);
+    pack.addFile("pack.json",
+                 R"json({"name": "base", "description": "the shipped content",
+                          "formatVersion": 1, "defaultSpace": "voxelforge"})json");
+    pack.addFile("data/voxelforge/recipes/redstone_torch.json", redstoneTorchShaped);
+    pack.addFile("data/voxelforge/recipes/bread.json", appleBread);
+    pack.addFile("data/voxelforge/recipes/sandstone.json", sandSmelting);
+    pack.addFile("data/voxelforge/lootTables/chests/starter.json", starterChest);
+    pack.addFile("data/voxelforge/tags/blocks/logs.json",
+                 R"json({"values": ["voxelforge:wood"]})json");
+    pack.addFile("data/voxelforge/tags/blocks/mineable.json",
+                 R"json({"values": ["#voxelforge:logs", "voxelforge:stone", "voxelforge:sand"]})json");
+    pack.addFile("data/voxelforge/tags/items/fuel.json",
+                 R"json({"values": ["voxelforge:coal_lump", "voxelforge:planks"]})json");
+    pack.addFile("readme.txt", "not a data file");
+    return pack;
+}
+
+DataPack overlayPack() {
+    DataPackMeta meta;
+    meta.name = "overlay";
+    meta.priority = 10;
+    DataPack pack(meta);
+    pack.addFile("data/voxelforge/recipes/redstone_torch.json", redstoneTorchRicher);
+    pack.addFile("data/voxelforge/tags/blocks/logs.json",
+                 R"json({"values": ["voxelforge:planks"]})json");
+    return pack;
+}
+
+} // namespace
+
+VF_TEST(resourceIdsAcceptNamespacedLowercasePathsAndRefuseTheRest) {
+    ResourceId parsed;
+    CHECK(ResourceId::parse("voxelforge:iron_ingot", "fallback", parsed));
+    CHECK_EQ(parsed.space, std::string("voxelforge"));
+    CHECK_EQ(parsed.path, std::string("iron_ingot"));
+    CHECK_EQ(parsed.text(), std::string("voxelforge:iron_ingot"));
+
+    CHECK(ResourceId::parse("chests/starter", "voxelforge", parsed));
+    CHECK_EQ(parsed.space, std::string("voxelforge"));
+    CHECK_EQ(parsed.path, std::string("chests/starter"));
+
+    CHECK(!ResourceId::parse("Voxelforge:stone", "voxelforge", parsed));
+    CHECK(!ResourceId::parse("voxelforge:Stone", "voxelforge", parsed));
+    CHECK(!ResourceId::parse("a:b:c", "voxelforge", parsed));
+    CHECK(!ResourceId::parse("", "voxelforge", parsed));
+    CHECK(!ResourceId::parse("voxelforge:", "voxelforge", parsed));
+    CHECK(!ResourceId::parse(":stone", "voxelforge", parsed));
+    CHECK(!ResourceId::parse("voxelforge:with space", "voxelforge", parsed));
+    CHECK(!ResourceId::parse("voxelforge://double", "voxelforge", parsed));
+    CHECK(!ResourceId::parse("voxelforge:/leading", "voxelforge", parsed));
+
+    CHECK(id("voxelforge:stone") == id("voxelforge:stone"));
+    CHECK(id("voxelforge:stone") != id("other:stone"));
+    CHECK(id("voxelforge:a") < id("voxelforge:b"));
+}
+
+VF_TEST(resourceIdsResolveOntoTheExistingBlockAndItemPalettes) {
+    ItemId item = ItemId::None;
+    CHECK(resolveItemId(id("voxelforge:iron_ingot"), item));
+    CHECK(item == ItemId::IronIngot);
+    CHECK(resolveItemId(id("voxelforge:crafting_table"), item));
+    CHECK(item == ItemId::CraftingTable);
+    CHECK(resolveItemId(id("voxelforge:stone"), item));
+    CHECK(item == ItemId::Stone);
+    CHECK(!resolveItemId(id("voxelforge:unobtainium"), item));
+
+    Block block = Block::Air;
+    CHECK(resolveBlockId(id("voxelforge:redstone_lamp"), block));
+    CHECK(block == Block::RedstoneLamp);
+    CHECK(resolveBlockId(id("voxelforge:packed_ice"), block));
+    CHECK(block == Block::PackedIce);
+    CHECK(!resolveBlockId(id("voxelforge:cheese"), block));
+}
+
+VF_TEST(packMetadataComesOutOfTheDataItself) {
+    DataPackLoader loader;
+    loader.addPack(basePack());
+    CHECK(loader.load());
+    CHECK_EQ(loader.errors().size(), static_cast<std::size_t>(0));
+    CHECK_EQ(loader.packs().size(), static_cast<std::size_t>(1));
+    const DataPackMeta& meta = loader.packs()[0].meta();
+    CHECK_EQ(meta.name, std::string("base"));
+    CHECK_EQ(meta.description, std::string("the shipped content"));
+    CHECK_EQ(meta.formatVersion, 1);
+    CHECK_EQ(meta.defaultSpace, std::string("voxelforge"));
+
+    DataPackMeta broken;
+    std::string problem;
+    JsonParseResult noName = parseJson(R"json({"description": "nameless"})json");
+    CHECK(!DataPackMeta::fromJson(noName.root, broken, problem));
+    CHECK(problem.find("name") != std::string::npos);
+