Replace mixin with access transformers

Hadn't realised I could use these to touch final modifiers! More
importantly, Mixin doesn't work with FG 5.0, so we needed an alternative
:).

build.gradle

@@ -5,16 +5,10 @@ buildscript {
             name = "forge"
             url = "https://maven.minecraftforge.net"
         }
-        maven {
-            name = "Sponge (Mixin)"
-            url = "https://repo.spongepowered.org/repository/maven-public/"
-            content { includeGroup "org.spongepowered" }
-        }
     }
     dependencies {
         classpath 'com.google.code.gson:gson:2.8.1'
         classpath 'net.minecraftforge.gradle:ForgeGradle:5.0.12'
-        classpath 'org.spongepowered:mixingradle:0.7-SNAPSHOT'
     }
 }
 
@@ -30,7 +24,6 @@ plugins {
 }
 
 apply plugin: 'net.minecraftforge.gradle'
-apply plugin: 'org.spongepowered.mixin'
 
 version = mod_version
 
@@ -68,9 +61,6 @@ minecraft {
             property 'forge.logging.markers', 'REGISTRIES'
             property 'forge.logging.console.level', 'debug'
 
-            property 'mixin.env.remapRefMap', 'true'
-            property 'mixin.env.refMapRemappingFile', "${buildDir}/createSrgToMcp/output.srg"
-
             mods {
                 computercraft {
                     source sourceSets.main
@@ -107,9 +97,6 @@ minecraft {
         testServer {
             workingDirectory project.file('test-files/server')
             parent runs.server
-            properties 'mixin.env.disableRefMap': 'true'
-
-            arg "-mixin.config=cctest.mixin.json"
             arg "--nogui"
 
             mods {
@@ -123,10 +110,7 @@ minecraft {
     mappings channel: 'official', version: mc_version
 
     accessTransformer file('src/main/resources/META-INF/accesstransformer.cfg')
-}
-
-mixin {
-    add sourceSets.test, "cctest.refmap.json"
+    accessTransformer file('src/test/resources/META-INF/accesstransformer.cfg')
 }
 
 sourceSets {
@@ -169,7 +153,6 @@ dependencies {
     testImplementation 'org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.3.72'
     testImplementation 'org.jetbrains.kotlin:kotlin-reflect:1.3.72'
     testImplementation 'org.jetbrains.kotlinx:kotlinx-coroutines-core:1.3.8'
-    testAnnotationProcessor 'org.spongepowered:mixin:0.8.2:processor'
 
     cctJavadoc 'cc.tweaked:cct-javadoc:1.4.0'
 }

src/test/java/dan200/computercraft/ingame/mod/TestLoader.java

@@ -17,7 +17,6 @@ import net.minecraftforge.fml.unsafe.UnsafeHacks;
 import net.minecraftforge.forgespi.language.ModFileScanData;
 import org.objectweb.asm.Type;
 
-import java.lang.reflect.Field;
 import java.lang.reflect.Method;
 import java.util.Arrays;
 import java.util.Collection;
@@ -87,29 +86,15 @@ class TestLoader
         long setupTicks
     )
     {
-        try
-        {
-            TestFunctionInfo func = UnsafeHacks.newInstance( TestFunctionInfo.class );
-            setFinalField( func, "batchName", batchName );
-            setFinalField( func, "testName", testName );
-            setFinalField( func, "structureName", structureName );
-            setFinalField( func, "required", required );
-            setFinalField( func, "function", function );
-            setFinalField( func, "maxTicks", maxTicks );
-            setFinalField( func, "setupTicks", setupTicks );
-            setFinalField( func, "rotation", Rotation.NONE );
-            return func;
-        }
-        catch( ReflectiveOperationException e )
-        {
-            throw new RuntimeException( e );
-        }
-    }
-
-    private static void setFinalField( TestFunctionInfo func, String name, Object value ) throws ReflectiveOperationException
-    {
-        Field field = TestFunctionInfo.class.getDeclaredField( name );
-        field.setAccessible( true );
-        field.set( func, value );
+        TestFunctionInfo func = UnsafeHacks.newInstance( TestFunctionInfo.class );
+        func.batchName = batchName;
+        func.testName = testName;
+        func.structureName = structureName;
+        func.required = required;
+        func.function = function;
+        func.maxTicks = maxTicks;
+        func.setupTicks = setupTicks;
+        func.rotation = Rotation.NONE;
+        return func;
     }
 }

src/test/resources/META-INF/accesstransformer.cfg

@@ -0,0 +1,8 @@
+public-f net.minecraft.test.TestFunctionInfo field_229650_a_
+public-f net.minecraft.test.TestFunctionInfo field_229651_b_
+public-f net.minecraft.test.TestFunctionInfo field_229652_c_
+public-f net.minecraft.test.TestFunctionInfo field_229653_d_
+public-f net.minecraft.test.TestFunctionInfo field_229654_e_
+public-f net.minecraft.test.TestFunctionInfo field_229655_f_
+public-f net.minecraft.test.TestFunctionInfo field_229656_g_
+public-f net.minecraft.test.TestFunctionInfo field_240589_h_

src/test/resources/cctest.mixin.json

@@ -1,10 +0,0 @@
-{
-    "required": true,
-    "package": "dan200.computercraft.ingame.mixin",
-    "compatibilityLevel": "JAVA_8",
-    "refmap": "cctest.refmap.json",
-    "mixins": [
-        "MixinTestFunctionInfo"
-    ],
-    "minVersion": "0.8"
-}