diff --git a/tests/testItem.cpp b/tests/testItem.cpp
new file mode 100644
index 0000000..64abc93
--- /dev/null
+++ b/tests/testItem.cpp
@@ -0,0 +1,143 @@
+#include "testHarness.h"
+#include "vf/Item.h"
+
+using namespace vf;
+
+VF_TEST(blockItemRoundTripsBothWays) {
+    CHECK(itemForBlock(Block::Stone) == ItemId::Stone);
+    CHECK(blockForItem(ItemId::Stone) == Block::Stone);
+    CHECK(itemForBlock(Block::CraftingTable) == ItemId::CraftingTable);
+    CHECK(blockForItem(ItemId::CraftingTable) == Block::CraftingTable);
+    CHECK(itemForBlock(Block::Tnt) == ItemId::Tnt);
+    CHECK(blockForItem(ItemId::Tnt) == Block::Tnt);
+}
+
+VF_TEST(blockItemMappingHasNoCounterpartForUnobtainableBlocks) {
+    CHECK(itemForBlock(Block::Bedrock) == ItemId::None);
+    CHECK(itemForBlock(Block::Air) == ItemId::None);
+    CHECK(itemForBlock(Block::Water) == ItemId::None);
+    CHECK(blockForItem(ItemId::IronIngot) == Block::Air);
+    CHECK(blockForItem(ItemId::Stick) == Block::Air);
+    CHECK(blockForItem(ItemId::WoodPickaxe) == Block::Air);
+}
+
+VF_TEST(itemKindsAndStackSizesAreCorrect) {
+    CHECK(isBlockItem(ItemId::Stone));
+    CHECK(!isBlockItem(ItemId::WoodPickaxe));
+    CHECK(isTool(ItemId::DiamondSword));
+    CHECK(!isTool(ItemId::Stone));
+    CHECK(isFood(ItemId::Bread));
+    CHECK(!isFood(ItemId::Stick));
+
+    CHECK_EQ(maxStackSize(ItemId::Stone), 64);
+    CHECK_EQ(maxStackSize(ItemId::WoodPickaxe), 1);
+    CHECK_EQ(maxStackSize(ItemId::Bread), 64);
+}
+
+VF_TEST(toolDurabilityRisesWithTierExceptGold) {
+    int wood = toolMaxDurability(ItemId::WoodPickaxe);
+    int stone = toolMaxDurability(ItemId::StonePickaxe);
+    int iron = toolMaxDurability(ItemId::IronPickaxe);
+    int gold = toolMaxDurability(ItemId::GoldPickaxe);
+    int diamond = toolMaxDurability(ItemId::DiamondPickaxe);
+
+    CHECK(wood > 0);
+    CHECK(stone > wood);
+    CHECK(iron > stone);
+    CHECK(diamond > iron);
+    CHECK(gold < wood);   // gold tools are notoriously fragile
+    CHECK_EQ(toolMaxDurability(ItemId::Stone), 0);
+}
+
+VF_TEST(correctToolMatchesExpectedBlockClasses) {
+    CHECK(correctToolFor(Block::Stone) == ToolType::Pickaxe);
+    CHECK(correctToolFor(Block::Cobblestone) == ToolType::Pickaxe);
+    CHECK(correctToolFor(Block::Wood) == ToolType::Axe);
+    CHECK(correctToolFor(Block::Planks) == ToolType::Axe);
+    CHECK(correctToolFor(Block::Dirt) == ToolType::Shovel);
+    CHECK(correctToolFor(Block::Sand) == ToolType::Shovel);
+    CHECK(correctToolFor(Block::Leaves) == ToolType::Hoe);
+    CHECK(correctToolFor(Block::Torch) == ToolType::None);
+}
+
+VF_TEST(miningSpeedMultiplierRewardsMatchingToolAndTier) {
+    CHECK_NEAR(miningSpeedMultiplier(ItemId::None, Block::Stone), 1.0f, 1e-6f);
+    CHECK_NEAR(miningSpeedMultiplier(ItemId::WoodPickaxe, Block::Stone), 2.0f, 1e-6f);
+    CHECK_NEAR(miningSpeedMultiplier(ItemId::DiamondPickaxe, Block::Stone), 8.0f, 1e-6f);
+    // Wrong tool class for the block: no bonus, same as bare hands.
+    CHECK_NEAR(miningSpeedMultiplier(ItemId::StonePickaxe, Block::Wood), 1.0f, 1e-6f);
+    CHECK_NEAR(miningSpeedMultiplier(ItemId::StoneAxe, Block::Wood), 4.0f, 1e-6f);
+}
+
+VF_TEST(damageToolBreaksAtZeroDurability) {
+    ItemSlot stack = makeToolStack(ItemId::WoodPickaxe);
+    int durability = stack.durability;
+    CHECK(durability > 0);
+
+    bool broke = false;
+    for (int i = 0; i < durability - 1; ++i) {
+        broke = damageTool(stack);
+        CHECK(!broke);
+        CHECK(!stack.empty());
+    }
+    broke = damageTool(stack);
+    CHECK(broke);
+    CHECK(stack.empty());
+    CHECK(stack.item == ItemId::None);
+}
+
+VF_TEST(damageToolIsNoOpOnNonTools) {
+    ItemSlot stack{ItemId::Stone, 10, 0};
+    bool broke = damageTool(stack);
+    CHECK(!broke);
+    CHECK_EQ(stack.count, 10);
+}
+
+VF_TEST(mergeStacksFillsUpToLimitAndLeavesRemainder) {
+    ItemSlot into{ItemId::Stone, 60, 0};
+    ItemSlot from{ItemId::Stone, 20, 0};
+    int moved = mergeStacks(into, from);
+    CHECK_EQ(moved, 4);
+    CHECK_EQ(into.count, 64);
+    CHECK_EQ(from.count, 16);
+}
+
+VF_TEST(mergeStacksIntoEmptyMovesEverything) {
+    ItemSlot into{};
+    ItemSlot from{ItemId::Cobblestone, 30, 0};
+    int moved = mergeStacks(into, from);
+    CHECK_EQ(moved, 30);
+    CHECK(into.item == ItemId::Cobblestone);
+    CHECK_EQ(into.count, 30);
+    CHECK(from.empty());
+}
+
+VF_TEST(mergeStacksRefusesDifferentItems) {
+    ItemSlot into{ItemId::Stone, 5, 0};
+    ItemSlot from{ItemId::Dirt, 5, 0};
+    int moved = mergeStacks(into, from);
+    CHECK_EQ(moved, 0);
+    CHECK_EQ(into.count, 5);
+    CHECK_EQ(from.count, 5);
+}
+
+VF_TEST(splitStackDividesAndEmptiesFully) {
+    ItemSlot stack{ItemId::Planks, 10, 0};
+    ItemSlot half = splitStack(stack, 4);
+    CHECK_EQ(half.count, 4);
+    CHECK(half.item == ItemId::Planks);
+    CHECK_EQ(stack.count, 6);
+
+    ItemSlot rest = splitStack(stack, 100);
+    CHECK_EQ(rest.count, 6);
+    CHECK(stack.empty());
+}
+
+VF_TEST(foodValueRewardsCookedOverRaw) {
+    FoodValue raw = foodValue(ItemId::RawPorkchop);
+    FoodValue cooked = foodValue(ItemId::CookedPorkchop);
+    CHECK(cooked.hunger > raw.hunger);
+    CHECK(cooked.saturation > raw.saturation);
+    FoodValue notFood = foodValue(ItemId::Stone);
+    CHECK_EQ(notFood.hunger, 0);
+}