Add NeoForge test

src/test/groovy/net/fabricmc/loom/test/integration/forge/ForgeTest.groovy

@@ -40,6 +40,8 @@ class ForgeTest extends Specification implements GradleProjectTestTrait {
 		gradle.buildGradle.text = gradle.buildGradle.text.replace('@MCVERSION@', mcVersion)
 				.replace('@FORGEVERSION@', forgeVersion)
 				.replace('@MAPPINGS@', mappings)
+				.replace('@REPOSITORIES@', '')
+				.replace('@PACKAGE@', 'net.minecraftforge:forge')
 
 		when:
 		def result = gradle.run(task: "build")
@@ -49,6 +51,8 @@ class ForgeTest extends Specification implements GradleProjectTestTrait {
 
 		where:
 		mcVersion | forgeVersion | mappings
+		'1.20.1'  | "47.2.1"     | "loom.officialMojangMappings()"
+		'1.20.1'  | "47.2.1"     | "'net.fabricmc:yarn:1.19.4+build.2:v2'"
 		'1.19.4'  | "45.0.43"    | "loom.officialMojangMappings()"
 		'1.19.4'  | "45.0.43"    | "'net.fabricmc:yarn:1.19.4+build.2:v2'"
 		'1.18.1'  | "39.0.63"    | "loom.officialMojangMappings()"

src/test/groovy/net/fabricmc/loom/test/integration/forge/NeoForgeTest.groovy

@@ -0,0 +1,56 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2021-2023 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.test.integration.forge
+
+import net.fabricmc.loom.test.util.GradleProjectTestTrait
+import spock.lang.Specification
+import spock.lang.Unroll
+
+import static net.fabricmc.loom.test.LoomTestConstants.DEFAULT_GRADLE
+import static org.gradle.testkit.runner.TaskOutcome.SUCCESS
+
+class NeoForgeTest extends Specification implements GradleProjectTestTrait {
+	@Unroll
+	def "build #mcVersion #forgeVersion #mappings"() {
+		setup:
+		def gradle = gradleProject(project: "forge/simple", version: DEFAULT_GRADLE)
+		gradle.buildGradle.text = gradle.buildGradle.text.replace('@MCVERSION@', mcVersion)
+				.replace('@FORGEVERSION@', forgeVersion)
+				.replace('@MAPPINGS@', mappings)
+				.replace('@REPOSITORIES@', 'maven { url "https://maven.neoforged.net/releases/" }')
+				.replace('@PACKAGE@', 'net.neoforged:forge')
+
+		when:
+		def result = gradle.run(task: "build")
+
+		then:
+		result.task(":build").outcome == SUCCESS
+
+		where:
+		mcVersion | forgeVersion | mappings
+		'1.20.1'  | "47.1.79"    | "loom.officialMojangMappings()"
+		'1.20.1'  | "47.1.79"    | "'net.fabricmc:yarn:1.20.1+build.1:v2'"
+	}
+}

src/test/resources/projects/forge/simple/build.gradle

@@ -24,13 +24,15 @@ repositories {
 	// Loom adds the essential maven repositories to download Minecraft and libraries from automatically.
 	// See https://docs.gradle.org/current/userguide/declaring_repositories.html
 	// for more information about repositories.
+
+	@REPOSITORIES@
 }
 
 dependencies {
 	// To change the versions see the gradle.properties file
 	minecraft "com.mojang:minecraft:$mcVersion"
 	mappings @MAPPINGS@
-	forge "net.minecraftforge:forge:$mcVersion-$forgeVersion"
+	forge "@PACKAGE@:$mcVersion-$forgeVersion"
 }
 
 tasks.withType(JavaCompile).configureEach {