test: characterize multipart event handler

Pin event annotations, bus identity, and server dispatch before the Java port.

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

@@ -0,0 +1,100 @@
+package codechicken.multipart.handler;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNull;
+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 org.junit.jupiter.api.Test;
+import org.objectweb.asm.Type;
+
+import cpw.mods.fml.common.eventhandler.EventPriority;
+import cpw.mods.fml.common.eventhandler.SubscribeEvent;
+import cpw.mods.fml.relauncher.Side;
+import cpw.mods.fml.relauncher.SideOnly;
+
+class MultipartEventHandlerCharacterizationTest {
+
+    private static final Set<String> EVENT_METHODS = new TreeSet<>(
+            Arrays.asList(
+                    "chunkUnWatch(Lnet/minecraftforge/event/world/ChunkWatchEvent$UnWatch;)V",
+                    "chunkWatch(Lnet/minecraftforge/event/world/ChunkWatchEvent$Watch;)V",
+                    "drawBlockHighlight(Lnet/minecraftforge/client/event/DrawBlockHighlightEvent;)V",
+                    "serverTick(Lcpw/mods/fml/common/gameevent/TickEvent$ServerTickEvent;)V",
+                    "tileEntityLoad(Lnet/minecraftforge/event/world/ChunkDataEvent$Load;)V",
+                    "worldUnLoad(Lnet/minecraftforge/event/world/WorldEvent$Unload;)V"));
+
+    @Test
+    void keepsBothSingletonTypesAndEventDescriptors() throws Exception {
+        assertHandlerType(MultipartEventHandler.class, true);
+        assertHandlerType(MultipartEventHandler$.class, false);
+
+        assertEquals(0, MultipartEventHandler.class.getFields().length);
+        Field module = MultipartEventHandler$.class.getField("MODULE$");
+        assertSame(MultipartEventHandler$.class, module.getType());
+        assertTrue(Modifier.isStatic(module.getModifiers()));
+        assertTrue(Modifier.isFinal(module.getModifiers()));
+        assertSame(MultipartEventHandler$.MODULE$, module.get(null));
+    }
+
+    @Test
+    void keepsEventPrioritiesAndClientOnlyHighlight() {
+        assertEventAnnotations(MultipartEventHandler.class);
+        assertEventAnnotations(MultipartEventHandler$.class);
+    }
+
+    private static void assertHandlerType(Class<?> type, boolean staticMethods) {
+        assertTrue(Modifier.isPublic(type.getModifiers()));
+        assertTrue(Modifier.isFinal(type.getModifiers()));
+        assertEquals(EVENT_METHODS, publicMethodSignatures(type));
+
+        for (Method method : type.getDeclaredMethods()) {
+            if (Modifier.isPublic(method.getModifiers())) {
+                assertEquals(staticMethods, Modifier.isStatic(method.getModifiers()));
+            }
+        }
+    }
+
+    private static void assertEventAnnotations(Class<?> type) {
+        for (Method method : type.getDeclaredMethods()) {
+            if (!Modifier.isPublic(method.getModifiers())) {
+                continue;
+            }
+
+            SubscribeEvent subscribe = method.getAnnotation(SubscribeEvent.class);
+            assertNotNull(subscribe, method.toString());
+            assertEquals(
+                    method.getName().equals("tileEntityLoad") ? EventPriority.HIGHEST : EventPriority.NORMAL,
+                    subscribe.priority(),
+                    method.toString());
+            assertFalse(subscribe.receiveCanceled(), method.toString());
+
+            SideOnly sideOnly = method.getAnnotation(SideOnly.class);
+            if (method.getName().equals("drawBlockHighlight")) {
+                assertNotNull(sideOnly, method.toString());
+                assertEquals(Side.CLIENT, sideOnly.value());
+            } else {
+                assertNull(sideOnly, method.toString());
+            }
+        }
+    }
+
+    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;
+    }
+}