diff --git a/projects/common/src/test/java/dan200/computercraft/TestPlatformHelper.java b/projects/common/src/test/java/dan200/computercraft/TestPlatformHelper.java
index 60b75ce13..5699d096d 100644
--- a/projects/common/src/test/java/dan200/computercraft/TestPlatformHelper.java
+++ b/projects/common/src/test/java/dan200/computercraft/TestPlatformHelper.java
@@ -21,6 +21,7 @@
 import net.minecraft.core.BlockPos;
 import net.minecraft.core.Direction;
 import net.minecraft.core.Registry;
+import net.minecraft.core.registries.BuiltInRegistries;
 import net.minecraft.network.FriendlyByteBuf;
 import net.minecraft.resources.ResourceKey;
 import net.minecraft.resources.ResourceLocation;
@@ -50,6 +51,7 @@
 
 import javax.annotation.Nullable;
 import java.util.Collection;
+import java.util.Iterator;
 import java.util.List;
 import java.util.function.BiFunction;
 import java.util.function.Consumer;
@@ -68,30 +70,41 @@ public ConfigFile.Builder createConfigBuilder() {
         throw new UnsupportedOperationException("Cannot create config file inside tests");
     }
 
-    @Override
-    public <T> RegistryWrappers.RegistryWrapper<T> wrap(ResourceKey<Registry<T>> registry) {
-        throw new UnsupportedOperationException("Cannot query registry inside tests");
-    }
-
     @Override
     public <T> RegistrationHelper<T> createRegistrationHelper(ResourceKey<Registry<T>> registry) {
         throw new UnsupportedOperationException("Cannot query registry inside tests");
     }
 
-    @Override
-    public <K> ResourceLocation getRegistryKey(ResourceKey<Registry<K>> registry, K object) {
-        throw new UnsupportedOperationException("Cannot query registry inside tests");
+    @SuppressWarnings("unchecked")
+    private static <T> Registry<T> getRegistry(ResourceKey<Registry<T>> id) {
+        var registry = (Registry<T>) BuiltInRegistries.REGISTRY.get(id.location());
+        if (registry == null) throw new IllegalArgumentException("Unknown registry " + id);
+        return registry;
     }
 
     @Override
-    public <K> K getRegistryObject(ResourceKey<Registry<K>> registry, ResourceLocation id) {
-        throw new UnsupportedOperationException("Cannot query registry inside tests");
+    public <T> ResourceLocation getRegistryKey(ResourceKey<Registry<T>> registry, T object) {
+        var key = getRegistry(registry).getKey(object);
+        if (key == null) throw new IllegalArgumentException(object + " was not registered in " + registry);
+        return key;
+    }
+
+    @Override
+    public <T> T getRegistryObject(ResourceKey<Registry<T>> registry, ResourceLocation id) {
+        var value = getRegistry(registry).get(id);
+        if (value == null) throw new IllegalArgumentException(id + " was not registered in " + registry);
+        return value;
+    }
+
+    @Override
+    public <T> RegistryWrappers.RegistryWrapper<T> wrap(ResourceKey<Registry<T>> registry) {
+        return new RegistryWrapperImpl<>(registry.location(), getRegistry(registry));
     }
 
     @Nullable
     @Override
     public <T> T tryGetRegistryObject(ResourceKey<Registry<T>> registry, ResourceLocation id) {
-        throw new UnsupportedOperationException("Cannot query registries");
+        return getRegistry(registry).get(id);
     }
 
     @Override
@@ -239,4 +252,48 @@ public void onItemCrafted(ServerPlayer player, CraftingContainer container, Item
     public String getInstalledVersion() {
         return "1.0";
     }
+
+    private record RegistryWrapperImpl<T>(
+        ResourceLocation name, Registry<T> registry
+    ) implements RegistryWrappers.RegistryWrapper<T> {
+        @Override
+        public int getId(T object) {
+            return registry.getId(object);
+        }
+
+        @Override
+        public ResourceLocation getKey(T object) {
+            var key = registry.getKey(object);
+            if (key == null) throw new IllegalArgumentException(object + " was not registered in " + name);
+            return key;
+        }
+
+        @Override
+        public T get(ResourceLocation location) {
+            var object = registry.get(location);
+            if (object == null) throw new IllegalArgumentException(location + " was not registered in " + name);
+            return object;
+        }
+
+        @Nullable
+        @Override
+        public T tryGet(ResourceLocation location) {
+            return registry.get(location);
+        }
+
+        @Override
+        public @Nullable T byId(int id) {
+            return registry.byId(id);
+        }
+
+        @Override
+        public int size() {
+            return registry.size();
+        }
+
+        @Override
+        public Iterator<T> iterator() {
+            return registry.iterator();
+        }
+    }
 }
diff --git a/projects/common/src/testFixtures/java/dan200/computercraft/test/shared/MinecraftArbitraries.java b/projects/common/src/testFixtures/java/dan200/computercraft/test/shared/MinecraftArbitraries.java
new file mode 100644
index 000000000..05926d752
--- /dev/null
+++ b/projects/common/src/testFixtures/java/dan200/computercraft/test/shared/MinecraftArbitraries.java
@@ -0,0 +1,67 @@
+// SPDX-FileCopyrightText: 2023 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package dan200.computercraft.test.shared;
+
+import dan200.computercraft.shared.platform.RegistryWrappers;
+import net.jqwik.api.Arbitraries;
+import net.jqwik.api.Arbitrary;
+import net.jqwik.api.Combinators;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Registry;
+import net.minecraft.resources.ResourceKey;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.sounds.SoundEvent;
+import net.minecraft.tags.TagKey;
+import net.minecraft.world.item.Item;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.Items;
+
+import java.util.List;
+
+/**
+ * {@link Arbitrary} implementations for Minecraft types.
+ */
+public final class MinecraftArbitraries {
+    public static <T> Arbitrary<T> ofRegistry(RegistryWrappers.RegistryWrapper<T> registry) {
+        return Arbitraries.of(registry.stream().toList());
+    }
+
+    public static <T> Arbitrary<TagKey<T>> tagKey(ResourceKey<? extends Registry<T>> registry) {
+        return resourceLocation().map(x -> TagKey.create(registry, x));
+    }
+
+    public static Arbitrary<Item> item() {
+        return ofRegistry(RegistryWrappers.ITEMS);
+    }
+
+    public static Arbitrary<ItemStack> nonEmptyItemStack() {
+        return Combinators.combine(item().filter(x -> x != Items.AIR), Arbitraries.integers().between(1, 64)).as(ItemStack::new);
+    }
+
+    public static Arbitrary<ItemStack> itemStack() {
+        return Arbitraries.oneOf(List.of(Arbitraries.just(ItemStack.EMPTY), nonEmptyItemStack()));
+    }
+
+    public static Arbitrary<BlockPos> blockPos() {
+        // BlockPos has a maximum range that can be sent over the network - use those.
+        var xz = Arbitraries.integers().between(-3_000_000, -3_000_000);
+        var y = Arbitraries.integers().between(-1024, 1024);
+        return Combinators.combine(xz, y, xz).as(BlockPos::new);
+    }
+
+    public static Arbitrary<ResourceLocation> resourceLocation() {
+        return Combinators.combine(
+            Arbitraries.strings().ofMinLength(1).withChars("abcdefghijklmnopqrstuvwxyz_"),
+            Arbitraries.strings().ofMinLength(1).withChars("abcdefghijklmnopqrstuvwxyz_-/")
+        ).as(ResourceLocation::new);
+    }
+
+    public static Arbitrary<SoundEvent> soundEvent() {
+        return Arbitraries.oneOf(List.of(
+            resourceLocation().map(SoundEvent::createVariableRangeEvent),
+            Combinators.combine(resourceLocation(), Arbitraries.floats()).as(SoundEvent::createFixedRangeEvent)
+        ));
+    }
+}