Fabric Game Test API

build.gradle

@@ -327,11 +327,19 @@ sourceSets {
 	testmod
 }
 
+// These modules are not included in the fat jar, maven will resolve them via the pom.
+def devOnlyModules = [
+		"fabric-game-test-api-v1"
+]
+
 dependencies {
 	afterEvaluate {
 		subprojects.each {
 			api project(path: ":${it.name}", configuration: "dev")
-			include project("${it.name}:")
+
+			if (!(it.name in devOnlyModules)) {
+				include project("${it.name}:")
+			}
 
 			testmodImplementation project("${it.name}:").sourceSets.testmod.output
 		}

fabric-game-test-api-v1/build.gradle

@@ -0,0 +1,24 @@
+archivesBaseName = "fabric-game-test-api-v1"
+version = getSubprojectVersion(project, "1.0.0")
+
+moduleDependencies(project, [
+		'fabric-api-base',
+		'fabric-resource-loader-v0'
+])
+
+
+loom {
+	runs {
+		gametest {
+			server()
+			name "Game Test"
+			vmArg "-Dfabric-api.gametest=true"
+			runDir "build/gametest"
+
+			// Specific to fabric api
+			source sourceSets.testmod
+			ideConfigGenerated true
+		}
+	}
+}
+test.dependsOn runGametest

fabric-game-test-api-v1/src/main/java/net/fabricmc/fabric/api/gametest/v1/FabricGameTest.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2016, 2017, 2018, 2019 FabricMC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.fabricmc.fabric.api.gametest.v1;
+
+import java.lang.reflect.Method;
+
+import net.minecraft.test.TestContext;
+
+import net.fabricmc.fabric.impl.gametest.FabricGameTestHelper;
+
+/**
+ * This interface can be optionally implemented on your test class.
+ */
+public interface FabricGameTest {
+	/**
+	 * Use in {@link net.minecraft.test.GameTest} structureName to use an empty 8x8 structure for the test.
+	 */
+	String EMPTY_STRUCTURE = "fabric-game-test-api-v1:empty";
+
+	/**
+	 * Override this method to implement custom logic to invoke the test method.
+	 * This can be used to run code before or after each test.
+	 * You can also pass in custom objects into the test method if desired.
+	 * The structure will have been placed in the world before this method is invoked.
+	 *
+	 * @param context The vanilla test context
+	 * @param method The test method to invoke
+	 */
+	default void invokeTestMethod(TestContext context, Method method) {
+		FabricGameTestHelper.invokeTestMethod(context, method, this);
+	}
+}

fabric-game-test-api-v1/src/main/java/net/fabricmc/fabric/impl/gametest/FabricGameTestHelper.java

@@ -0,0 +1,109 @@
+/*
+ * Copyright (c) 2016, 2017, 2018, 2019 FabricMC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.fabricmc.fabric.impl.gametest;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.Collection;
+import java.util.function.Consumer;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.jetbrains.annotations.ApiStatus;
+
+import net.minecraft.resource.ResourcePackManager;
+import net.minecraft.resource.ServerResourceManager;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.test.GameTestBatch;
+import net.minecraft.test.TestContext;
+import net.minecraft.test.TestFunction;
+import net.minecraft.test.TestFunctions;
+import net.minecraft.test.TestServer;
+import net.minecraft.test.TestUtil;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.util.registry.DynamicRegistryManager;
+import net.minecraft.world.level.storage.LevelStorage;
+
+import net.fabricmc.fabric.api.gametest.v1.FabricGameTest;
+import net.fabricmc.loader.FabricLoader;
+
+@ApiStatus.Internal
+public final class FabricGameTestHelper {
+	public static final boolean ENABLED = System.getProperty("fabric-api.gametest") != null;
+
+	private static final Logger LOGGER = LogManager.getLogger();
+
+	private FabricGameTestHelper() {
+	}
+
+	public static void runHeadlessServer(LevelStorage.Session session, ResourcePackManager resourcePackManager, ServerResourceManager serverResourceManager, DynamicRegistryManager.Impl registryManager) {
+		LOGGER.info("Starting test server");
+		MinecraftServer server = TestServer.startServer(thread -> {
+			TestServer testServer = new TestServer(thread, session, resourcePackManager, serverResourceManager, getBatches(), BlockPos.ORIGIN, registryManager);
+			FabricLoader.INSTANCE.setGameInstance(testServer);
+			return testServer;
+		});
+	}
+
+	// Moved out to here as I expect we will want a FabricTestContext, or a way for a mod to provide their own context
+	// We can also have better error handling.
+	public static Consumer<TestContext> getTestMethodInvoker(Method method) {
+		return testContext -> {
+			Class<?> testClass = method.getDeclaringClass();
+
+			Constructor<?> constructor;
+
+			try {
+				constructor = testClass.getConstructor();
+			} catch (NoSuchMethodException e) {
+				throw new RuntimeException("Test class (%s) provided by (%s) must have a public default or no args constructor".formatted(testClass.getSimpleName(), FabricGameTestModInitializer.getModIdForTestClass(testClass)));
+			}
+
+			Object testObject;
+
+			try {
+				testObject = constructor.newInstance();
+			} catch (InvocationTargetException | InstantiationException | IllegalAccessException e) {
+				throw new RuntimeException("Failed to create instance of test class (%s)".formatted(testClass.getCanonicalName()), e);
+			}
+
+			if (testClass.isAssignableFrom(FabricGameTest.class)) {
+				FabricGameTest fabricGameTest = (FabricGameTest) testObject;
+				fabricGameTest.invokeTestMethod(testContext, method);
+			} else {
+				invokeTestMethod(testContext, method, testObject);
+			}
+		};
+	}
+
+	public static void invokeTestMethod(TestContext testContext, Method method, Object testObject) {
+		try {
+			method.invoke(testObject, testContext);
+		} catch (IllegalAccessException | InvocationTargetException e) {
+			throw new RuntimeException("Failed to invoke test method (%s) in (%s)".formatted(method.getName(), method.getDeclaringClass().getCanonicalName()), e);
+		}
+	}
+
+	private static Collection<GameTestBatch> getBatches() {
+		return TestUtil.createBatches(getTestFunctions());
+	}
+
+	private static Collection<TestFunction> getTestFunctions() {
+		return TestFunctions.getTestFunctions();
+	}
+}

fabric-game-test-api-v1/src/main/java/net/fabricmc/fabric/impl/gametest/FabricGameTestModInitializer.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright (c) 2016, 2017, 2018, 2019 FabricMC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.fabricmc.fabric.impl.gametest;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.jetbrains.annotations.ApiStatus;
+
+import net.minecraft.test.TestFunctions;
+
+import net.fabricmc.api.ModInitializer;
+import net.fabricmc.loader.api.FabricLoader;
+import net.fabricmc.loader.api.entrypoint.EntrypointContainer;
+
+@ApiStatus.Internal
+public final class FabricGameTestModInitializer implements ModInitializer {
+	private static final String ENTRYPOINT_KEY = "fabric-game-test";
+	private static final Map<Class<?>, String> GAME_TEST_IDS = new HashMap<>();
+	private static final Logger LOGGER = LogManager.getLogger();
+
+	@Override
+	public void onInitialize() {
+		List<EntrypointContainer<Object>> entrypointContainers = FabricLoader.getInstance()
+				.getEntrypointContainers(ENTRYPOINT_KEY, Object.class);
+
+		for (EntrypointContainer<Object> container : entrypointContainers) {
+			Class<?> testClass = container.getEntrypoint().getClass();
+			String modid = container.getProvider().getMetadata().getId();
+
+			if (GAME_TEST_IDS.containsKey(testClass)) {
+				throw new UnsupportedOperationException("Test class (%s) has already been registered with mod (%s)".formatted(testClass.getCanonicalName(), modid));
+			}
+
+			GAME_TEST_IDS.put(testClass, modid);
+			TestFunctions.register(testClass);
+
+			LOGGER.debug("Registered test class {} for mod {}", testClass.getCanonicalName(), modid);
+		}
+	}
+
+	public static String getModIdForTestClass(Class<?> testClass) {
+		if (!GAME_TEST_IDS.containsKey(testClass)) {
+			throw new UnsupportedOperationException("The test class (%s) was not registered using the '%s' entrypoint".formatted(testClass.getCanonicalName(), ENTRYPOINT_KEY));
+		}
+
+		return GAME_TEST_IDS.get(testClass);
+	}
+}

fabric-game-test-api-v1/src/main/java/net/fabricmc/fabric/mixin/gametest/CommandManagerMixin.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2016, 2017, 2018, 2019 FabricMC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.fabricmc.fabric.mixin.gametest;
+
+import org.spongepowered.asm.mixin.Final;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+import com.mojang.brigadier.CommandDispatcher;
+
+import net.minecraft.SharedConstants;
+import net.minecraft.server.command.CommandManager;
+import net.minecraft.server.command.ServerCommandSource;
+import net.minecraft.server.command.TestCommand;
+
+@Mixin(CommandManager.class)
+public abstract class CommandManagerMixin {
+	@Shadow
+	@Final
+	private CommandDispatcher<ServerCommandSource> dispatcher;
+
+	@Inject(method = "<init>", at = @At(value = "INVOKE", target = "Lnet/minecraft/server/command/WorldBorderCommand;register(Lcom/mojang/brigadier/CommandDispatcher;)V", shift = At.Shift.AFTER))
+	private void construct(CommandManager.RegistrationEnvironment environment, CallbackInfo info) {
+		// Registered by vanilla when isDevelopment is enabled.
+		if (!SharedConstants.isDevelopment) {
+			TestCommand.register(this.dispatcher);
+		}
+	}
+}

fabric-game-test-api-v1/src/main/java/net/fabricmc/fabric/mixin/gametest/MinecraftServerMixin.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2016, 2017, 2018, 2019 FabricMC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.fabricmc.fabric.mixin.gametest;
+
+import java.util.function.BooleanSupplier;
+
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+import net.minecraft.SharedConstants;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.test.TestManager;
+
+@Mixin(MinecraftServer.class)
+public abstract class MinecraftServerMixin {
+	@Inject(method = "tickWorlds", at = @At(value = "INVOKE", target = "Lnet/minecraft/server/PlayerManager;updatePlayerLatency()V", shift = At.Shift.AFTER))
+	private void tickWorlds(BooleanSupplier shouldKeepTicking, CallbackInfo callbackInfo) {
+		// Registered by vanilla when isDevelopment is enabled.
+		if (!SharedConstants.isDevelopment) {
+			TestManager.INSTANCE.tick();
+		}
+	}
+}