[No CI] Add a gametest for startup configs

tests/build.gradle

@@ -109,6 +109,8 @@ afterEvaluate {
         args.set(outputIndex+1, file('src/generated/resources/').absolutePath);
         programArguments.set(args);
     }
+    runs.junit.modSources = runs.junit.modSources.get().stream()
+        .filter { it != sourceSets.main }.toList()
 }
 
 license {

tests/src/junit/java/net/neoforged/neoforge/unittest/StartupConfigTest.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) NeoForged and contributors
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+
+package net.neoforged.neoforge.unittest;
+
+import net.neoforged.fml.ModContainer;
+import net.neoforged.fml.common.Mod;
+import net.neoforged.fml.config.ModConfig;
+import net.neoforged.neoforge.common.ModConfigSpec;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.MethodOrderer;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.TestMethodOrder;
+
+@TestMethodOrder(MethodOrderer.MethodName.class)
+public class StartupConfigTest {
+    private static final String MOD_ID = "startup_config_test";
+    private static boolean wasLoadedAtInitStartupConfig = false;
+    private static boolean wasLoadedAtInitCommonConfig = false;
+    private static boolean wasLoadedAtInitServerConfig = false;
+    private static boolean wasLoadedAtInitClientConfig = false;
+
+    @Test
+    void testStartupConfigs() {
+        Assertions.assertTrue(wasLoadedAtInitStartupConfig, "Startup Config was supposed to be loaded at mod init.");
+        Assertions.assertFalse(wasLoadedAtInitCommonConfig, "Common Config was NOT supposed to be loaded at mod init.");
+        Assertions.assertFalse(wasLoadedAtInitServerConfig, "Server Config was NOT supposed to be loaded at mod init.");
+        Assertions.assertFalse(wasLoadedAtInitClientConfig, "Client Config was NOT supposed to be loaded at mod init.");
+    }
+
+    @Mod(value = MOD_ID)
+    public static class StartupConfigTestMod {
+        public StartupConfigTestMod(ModContainer modContainer) {
+            modContainer.registerConfig(ModConfig.Type.STARTUP, StartupConfig.SPEC);
+            modContainer.registerConfig(ModConfig.Type.COMMON, CommonConfig.SPEC);
+            modContainer.registerConfig(ModConfig.Type.SERVER, ServerConfig.SPEC);
+            modContainer.registerConfig(ModConfig.Type.CLIENT, ClientConfig.SPEC);
+            wasLoadedAtInitStartupConfig = StartupConfig.SPEC.isLoaded();
+            wasLoadedAtInitCommonConfig = CommonConfig.SPEC.isLoaded();
+            wasLoadedAtInitServerConfig = ServerConfig.SPEC.isLoaded();
+            wasLoadedAtInitClientConfig = ClientConfig.SPEC.isLoaded();
+        }
+
+        public static class StartupConfig {
+            private static final ModConfigSpec.Builder BUILDER = new ModConfigSpec.Builder();
+            private static final ModConfigSpec.BooleanValue TEST_MARKER = BUILDER.define("testMarker1", true);
+            static final ModConfigSpec SPEC = BUILDER.build();
+        }
+
+        public static class CommonConfig {
+            private static final ModConfigSpec.Builder BUILDER = new ModConfigSpec.Builder();
+            private static final ModConfigSpec.BooleanValue TEST_MARKER = BUILDER.define("testMarker2", true);
+            static final ModConfigSpec SPEC = BUILDER.build();
+        }
+
+        public static class ServerConfig {
+            private static final ModConfigSpec.Builder BUILDER = new ModConfigSpec.Builder();
+            private static final ModConfigSpec.BooleanValue TEST_MARKER = BUILDER.define("testMarker3", true);
+            static final ModConfigSpec SPEC = BUILDER.build();
+        }
+
+        public static class ClientConfig {
+            private static final ModConfigSpec.Builder BUILDER = new ModConfigSpec.Builder();
+            private static final ModConfigSpec.BooleanValue TEST_MARKER = BUILDER.define("testMarker4", true);
+            static final ModConfigSpec SPEC = BUILDER.build();
+        }
+    }
+}

tests/src/junit/resources/META-INF/neoforge.mods.toml

@@ -0,0 +1,8 @@
+modLoader="javafml"
+loaderVersion="[1,)"
+license="LGPL v2.1"
+
+[[mods]]
+modId="startup_config_test"
+[[mods]]
+modId="creative_tab_order_test"

tests/src/main/resources/META-INF/neoforge.mods.toml

@@ -37,9 +37,6 @@ license="LGPL v2.1"
 [[mods]]
     modId="multiple_entrypoints_test"
 
-[[mods]]
-    modId="creative_tab_order_test"
-
 [[mods]]
     modId="ordered_test_1"
 [[mods]]