Add DSL to configure Fabric API game tests (#1240)

* Add DSL to configure game tests

* Small cleanup

* More work

src/main/java/net/fabricmc/loom/api/fabricapi/FabricApiExtension.java

@@ -1,7 +1,7 @@
 /*
  * This file is part of fabric-loom, licensed under the MIT License (MIT).
  *
- * Copyright (c) 2024 FabricMC
+ * Copyright (c) 2024-2025 FabricMC
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -26,6 +26,7 @@
 
 import org.gradle.api.Action;
 import org.gradle.api.artifacts.Dependency;
+import org.jetbrains.annotations.ApiStatus;
 
 /**
  * A gradle extension with specific functionality related to Fabric API.
@@ -58,4 +59,17 @@ public interface FabricApiExtension {
 	 * @param action An action to configure specific data generation settings. See {@link DataGenerationSettings} for more information.
 	 */
 	void configureDataGeneration(Action<DataGenerationSettings> action);
+
+	/**
+	 * Configuration of game and client tests using the default settings.
+	 */
+	@ApiStatus.Experimental
+	void configureTests();
+
+	/**
+	 * Configuration of game and/or client tests using the specified settings.
+	 * @param action An action to configure specific game test settings. See {@link GameTestSettings} for more information.
+	 */
+	@ApiStatus.Experimental
+	void configureTests(Action<GameTestSettings> action);
 }

src/main/java/net/fabricmc/loom/api/fabricapi/GameTestSettings.java

@@ -0,0 +1,82 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2025 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.api.fabricapi;
+
+import org.gradle.api.provider.Property;
+import org.gradle.api.tasks.Optional;
+import org.jetbrains.annotations.ApiStatus;
+
+/**
+ * Represents the settings for game and/or client tests.
+ */
+@ApiStatus.Experimental
+public interface GameTestSettings {
+	/**
+	 * Contains a boolean property indicating whether a new source set should be created for the tests.
+	 *
+	 * <p>Default: false
+	 */
+	Property<Boolean> getCreateSourceSet();
+
+	/**
+	 * Contains a string property representing the mod ID associated with the tests.
+	 *
+	 * <p>This must be set when {@link #getCreateSourceSet()} is set.
+	 */
+	@Optional
+	Property<String> getModId();
+
+	/**
+	 * Contains a boolean property indicating whether a run configuration will be created for the server side game tests, using Vanilla Game Test framework.
+	 *
+	 * <p>Default: true
+	 */
+	Property<Boolean> getEnableGameTests();
+
+	/**
+	 * Contains a boolean property indicating whether a run configuration will be created for the client side game tests, using the Fabric API Client Test framework.
+	 *
+	 * <p>Default: true
+	 */
+	Property<Boolean> getEnableClientGameTests();
+
+	/**
+	 * Contains a boolean property indicating whether the eula has been accepted. By enabling this you agree to the Minecraft EULA located at <a href="https://aka.ms/MinecraftEULA">https://aka.ms/MinecraftEULA</a>.
+	 *
+	 * <p>This only works when {@link #getEnableClientGameTests()} is enabled.
+	 *
+	 * <p>Default: false
+	 */
+	Property<Boolean> getEula();
+
+	/**
+	 * Contains a boolean property indicating whether the run directories should be cleared before running the tests.
+	 *
+	 * <p>This only works when {@link #getEnableClientGameTests()} is enabled.
+	 *
+	 * <p>Default: true
+	 */
+	Property<Boolean> getClearRunDirectory();
+}

src/main/java/net/fabricmc/loom/configuration/fabricapi/FabricApiExtensionImpl.java

@@ -1,7 +1,7 @@
 /*
  * This file is part of fabric-loom, licensed under the MIT License (MIT).
  *
- * Copyright (c) 2020-2023 FabricMC
+ * Copyright (c) 2020-2025 FabricMC
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -32,17 +32,20 @@
 
 import net.fabricmc.loom.api.fabricapi.DataGenerationSettings;
 import net.fabricmc.loom.api.fabricapi.FabricApiExtension;
+import net.fabricmc.loom.api.fabricapi.GameTestSettings;
 
 public abstract class FabricApiExtensionImpl implements FabricApiExtension {
 	@Inject
 	protected abstract ObjectFactory getObjectFactory();
 
 	private final FabricApiVersions versions;
 	private final FabricApiDataGeneration dataGeneration;
+	private final FabricApiTesting testing;
 
 	public FabricApiExtensionImpl() {
 		versions = getObjectFactory().newInstance(FabricApiVersions.class);
 		dataGeneration = getObjectFactory().newInstance(FabricApiDataGeneration.class);
+		testing = getObjectFactory().newInstance(FabricApiTesting.class);
 	}
 
 	@Override
@@ -64,4 +67,14 @@ public void configureDataGeneration() {
 	public void configureDataGeneration(Action<DataGenerationSettings> action) {
 		dataGeneration.configureDataGeneration(action);
 	}
+
+	@Override
+	public void configureTests() {
+		configureTests(gameTestSettings -> { });
+	}
+
+	@Override
+	public void configureTests(Action<GameTestSettings> action) {
+		testing.configureTests(action);
+	}
 }

src/main/java/net/fabricmc/loom/configuration/fabricapi/FabricApiTesting.java

@@ -0,0 +1,144 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2025 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.configuration.fabricapi;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.function.Consumer;
+
+import javax.inject.Inject;
+
+import org.gradle.api.Action;
+import org.gradle.api.Project;
+import org.gradle.api.file.RegularFileProperty;
+import org.gradle.api.tasks.Delete;
+import org.gradle.api.tasks.OutputFile;
+import org.gradle.api.tasks.TaskAction;
+import org.gradle.api.tasks.TaskContainer;
+
+import net.fabricmc.loom.LoomGradleExtension;
+import net.fabricmc.loom.api.fabricapi.GameTestSettings;
+import net.fabricmc.loom.configuration.ide.RunConfigSettings;
+import net.fabricmc.loom.task.AbstractLoomTask;
+import net.fabricmc.loom.task.LoomTasks;
+import net.fabricmc.loom.util.Constants;
+
+public abstract class FabricApiTesting extends FabricApiAbstractSourceSet {
+	@Inject
+	protected abstract Project getProject();
+
+	@Inject
+	public FabricApiTesting() {
+	}
+
+	@Override
+	protected String getSourceSetName() {
+		return "gametest";
+	}
+
+	void configureTests(Action<GameTestSettings> action) {
+		final LoomGradleExtension extension = LoomGradleExtension.get(getProject());
+		final TaskContainer tasks = getProject().getTasks();
+
+		GameTestSettings settings = getProject().getObjects().newInstance(GameTestSettings.class);
+		settings.getCreateSourceSet().convention(false);
+		settings.getEnableGameTests().convention(true);
+		settings.getEnableClientGameTests().convention(true);
+		settings.getEula().convention(false);
+		settings.getClearRunDirectory().convention(true);
+
+		action.execute(settings);
+
+		if (settings.getCreateSourceSet().get()) {
+			configureSourceSet(settings.getModId(), true);
+		}
+
+		Consumer<RunConfigSettings> configureBase = run -> {
+			if (settings.getCreateSourceSet().get()) {
+				run.source(getSourceSetName());
+			}
+		};
+
+		if (settings.getEnableGameTests().get()) {
+			RunConfigSettings gameTest = extension.getRunConfigs().create("gameTest", run -> {
+				run.inherit(extension.getRunConfigs().getByName("server"));
+				run.property("fabric-api.gametest");
+				run.runDir("build/run/gameTest");
+				configureBase.accept(run);
+			});
+
+			tasks.named("test", task -> task.dependsOn(LoomTasks.getRunConfigTaskName(gameTest)));
+		}
+
+		if (settings.getEnableClientGameTests().get()) {
+			RunConfigSettings clientGameTest = extension.getRunConfigs().create("clientGameTest", run -> {
+				run.inherit(extension.getRunConfigs().getByName("client"));
+				run.property("fabric.client.gametest");
+				run.runDir("build/run/clientGameTest");
+				configureBase.accept(run);
+			});
+
+			if (settings.getClearRunDirectory().get()) {
+				var deleteGameTestRunDir = tasks.register("deleteGameTestRunDir", Delete.class, task -> {
+					task.setGroup(Constants.TaskGroup.FABRIC);
+					task.delete(clientGameTest.getRunDir());
+				});
+
+				tasks.named(LoomTasks.getRunConfigTaskName(clientGameTest), task -> task.dependsOn(deleteGameTestRunDir));
+			}
+
+			if (settings.getEula().get()) {
+				var acceptEula = tasks.register("acceptGameTestEula", AcceptEulaTask.class, task -> {
+					task.getEulaFile().set(getProject().file(clientGameTest.getRunDir() + "/eula.txt"));
+
+					if (settings.getClearRunDirectory().get()) {
+						// Ensure that the eula is accepted after the run directory is cleared
+						task.dependsOn(tasks.named("deleteGameTestRunDir"));
+					}
+				});
+
+				tasks.named("configureLaunch", task -> task.dependsOn(acceptEula));
+			}
+		}
+	}
+
+	public abstract static class AcceptEulaTask extends AbstractLoomTask {
+		@OutputFile
+		public abstract RegularFileProperty getEulaFile();
+
+		@TaskAction
+		public void acceptEula() throws IOException {
+			final Path eula = getEulaFile().get().getAsFile().toPath();
+
+			if (Files.notExists(eula)) {
+				Files.writeString(eula, """
+						#This file was generated by the Fabric Loom Gradle plugin. As the user opted into accepting the EULA.
+						eula=true
+						""");
+			}
+		}
+	}
+}

src/main/java/net/fabricmc/loom/task/LoomTasks.java

@@ -126,7 +126,7 @@ private void registerIDETasks() {
 		});
 	}
 
-	private static String getRunConfigTaskName(RunConfigSettings config) {
+	public static String getRunConfigTaskName(RunConfigSettings config) {
 		String configName = config.getName();
 		return "run" + configName.substring(0, 1).toUpperCase() + configName.substring(1);
 	}