test: characterize multipart save/load

src/test/java/codechicken/multipart/handler/MultipartSaveLoadCharacterizationTest.java

@@ -0,0 +1,129 @@
+package codechicken.multipart.handler;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertSame;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
+import java.util.Arrays;
+import java.util.Set;
+import java.util.TreeSet;
+
+import net.minecraft.nbt.NBTTagCompound;
+import net.minecraft.tileentity.TileEntity;
+
+import org.junit.jupiter.api.Test;
+import org.objectweb.asm.Type;
+
+class MultipartSaveLoadCharacterizationTest {
+
+    private static final Set<String> METHODS = new TreeSet<>(
+            Arrays.asList(
+                    "converters()Lscala/collection/mutable/MutableList;",
+                    "getClassToNameMap()Ljava/util/Map;",
+                    "hookLoader()V",
+                    "loadTiles(Lnet/minecraft/world/chunk/Chunk;)V",
+                    "loadingWorld()Lnet/minecraft/world/World;",
+                    "loadingWorld_$eq(Lnet/minecraft/world/World;)V",
+                    "registerTileClass(Ljava/lang/Class;)V"));
+
+    @Test
+    void keepsTheStaticFacadeAndLoadBearingCompanion() throws Exception {
+        Class<?> facade = load("codechicken.multipart.handler.MultipartSaveLoad");
+        Class<?> companion = load("codechicken.multipart.handler.MultipartSaveLoad$");
+
+        assertTrue(Modifier.isPublic(facade.getModifiers()));
+        assertTrue(Modifier.isFinal(facade.getModifiers()));
+        assertEquals(METHODS, publicMethodSignatures(facade));
+        for (Method method : facade.getDeclaredMethods()) {
+            if (Modifier.isPublic(method.getModifiers())) {
+                assertTrue(Modifier.isStatic(method.getModifiers()), method.toString());
+            }
+        }
+
+        assertTrue(Modifier.isPublic(companion.getModifiers()));
+        assertTrue(Modifier.isFinal(companion.getModifiers()));
+        assertSame(Object.class, companion.getSuperclass());
+        assertArrayEquals(new Class<?>[0], companion.getInterfaces());
+        assertEquals(METHODS, publicMethodSignatures(companion));
+        for (Method method : companion.getDeclaredMethods()) {
+            if (Modifier.isPublic(method.getModifiers())) {
+                assertFalse(Modifier.isStatic(method.getModifiers()), method.toString());
+            }
+        }
+
+        Field module = companion.getField("MODULE$");
+        assertSame(companion, module.getType());
+        assertTrue(Modifier.isStatic(module.getModifiers()));
+        assertTrue(Modifier.isFinal(module.getModifiers()));
+    }
+
+    @Test
+    void keepsTheCompanionStateFields() throws Exception {
+        Class<?> companion = load("codechicken.multipart.handler.MultipartSaveLoad$");
+
+        assertField(companion, "converters", "scala.collection.mutable.MutableList", true);
+        assertField(companion, "loadingWorld", "net.minecraft.world.World", false);
+        assertField(companion, "classToNameMap", "java.util.Map", true);
+    }
+
+    @Test
+    void keepsTheNbtContainerShapeAndReadBehavior() throws Exception {
+        Class<?> type = load("codechicken.multipart.handler.MultipartSaveLoad$TileNBTContainer");
+        assertTrue(Modifier.isPublic(type.getModifiers()));
+        assertTrue(Modifier.isStatic(type.getModifiers()));
+        assertFalse(Modifier.isFinal(type.getModifiers()));
+        assertSame(load("codechicken.multipart.handler.MultipartSaveLoad"), type.getEnclosingClass());
+        assertSame(TileEntity.class, type.getSuperclass());
+        assertArrayEquals(new Class<?>[0], type.getInterfaces());
+        assertEquals(
+                new TreeSet<>(
+                        Arrays.asList(
+                                "readFromNBT(Lnet/minecraft/nbt/NBTTagCompound;)V",
+                                "tag()Lnet/minecraft/nbt/NBTTagCompound;",
+                                "tag_$eq(Lnet/minecraft/nbt/NBTTagCompound;)V")),
+                publicMethodSignatures(type));
+
+        Field field = type.getDeclaredField("tag");
+        assertSame(NBTTagCompound.class, field.getType());
+        assertTrue(Modifier.isPrivate(field.getModifiers()));
+        assertFalse(Modifier.isFinal(field.getModifiers()));
+
+        TileEntity tile = (TileEntity) type.getDeclaredConstructor().newInstance();
+        NBTTagCompound tag = new NBTTagCompound();
+        tag.setInteger("x", 12);
+        tag.setInteger("y", 34);
+        tag.setInteger("z", 56);
+        type.getMethod("readFromNBT", NBTTagCompound.class).invoke(tile, tag);
+
+        assertEquals(12, tile.xCoord);
+        assertEquals(34, tile.yCoord);
+        assertEquals(56, tile.zCoord);
+        assertSame(tag, type.getMethod("tag").invoke(tile));
+    }
+
+    private static Class<?> load(String name) throws ClassNotFoundException {
+        return Class.forName(name, false, MultipartSaveLoadCharacterizationTest.class.getClassLoader());
+    }
+
+    private static void assertField(Class<?> owner, String name, String typeName, boolean isFinal) throws Exception {
+        Field field = owner.getDeclaredField(name);
+        assertEquals(typeName, field.getType().getName());
+        assertTrue(Modifier.isPrivate(field.getModifiers()));
+        assertEquals(isFinal, Modifier.isFinal(field.getModifiers()));
+    }
+
+    private static Set<String> publicMethodSignatures(Class<?> type) {
+        Set<String> signatures = new TreeSet<>();
+        for (Method method : type.getDeclaredMethods()) {
+            if (Modifier.isPublic(method.getModifiers())) {
+                signatures.add(method.getName() + Type.getMethodDescriptor(method));
+            }
+        }
+        return signatures;
+    }
+}