Explicitly rewrite legacy plugin message channels for 1.13+ clients.

proxy/src/test/java/com/velocitypowered/proxy/protocol/util/PluginMessageUtilTest.java

@@ -0,0 +1,36 @@
+package com.velocitypowered.proxy.protocol.util;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+class PluginMessageUtilTest {
+
+  @Test
+  void transformLegacyToModernChannelWorksWithModern() {
+    assertEquals("minecraft:brand", PluginMessageUtil
+        .transformLegacyToModernChannel("minecraft:brand"));
+    assertEquals("velocity:test", PluginMessageUtil
+        .transformLegacyToModernChannel("velocity:test"));
+  }
+
+  @Test
+  void transformLegacyToModernChannelRewritesSpecialCases() {
+    assertEquals("minecraft:brand", PluginMessageUtil
+        .transformLegacyToModernChannel("MC|Brand"));
+    assertEquals("minecraft:register", PluginMessageUtil
+        .transformLegacyToModernChannel("REGISTER"));
+    assertEquals("minecraft:unregister", PluginMessageUtil
+        .transformLegacyToModernChannel("UNREGISTER"));
+    assertEquals("bungeecord:main", PluginMessageUtil
+        .transformLegacyToModernChannel("BungeeCord"));
+  }
+
+  @Test
+  void transformLegacyToModernChannelRewritesGeneral() {
+    assertEquals("legacy:example", PluginMessageUtil
+        .transformLegacyToModernChannel("Example"));
+    assertEquals("legacy:pskeepalive", PluginMessageUtil
+        .transformLegacyToModernChannel("PS|KeepAlive"));
+  }
+}

proxy/src/test/java/com/velocitypowered/proxy/util/VelocityChannelRegistrarTest.java

@@ -0,0 +1,55 @@
+package com.velocitypowered.proxy.util;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import com.google.common.collect.ImmutableSet;
+import com.velocitypowered.api.proxy.messages.LegacyChannelIdentifier;
+import com.velocitypowered.api.proxy.messages.MinecraftChannelIdentifier;
+import org.junit.jupiter.api.Test;
+
+class VelocityChannelRegistrarTest {
+
+  private static final MinecraftChannelIdentifier MODERN = MinecraftChannelIdentifier
+      .create("velocity", "test");
+  private static final LegacyChannelIdentifier SIMPLE_LEGACY =
+      new LegacyChannelIdentifier("VelocityTest");
+
+  private static final MinecraftChannelIdentifier MODERN_SPECIAL_REMAP = MinecraftChannelIdentifier
+      .create("bungeecord", "main");
+  private static final LegacyChannelIdentifier SPECIAL_REMAP_LEGACY =
+      new LegacyChannelIdentifier("BungeeCord");
+
+  private static final String SIMPLE_LEGACY_REMAPPED = "legacy:velocitytest";
+
+  @Test
+  void register() {
+    VelocityChannelRegistrar registrar = new VelocityChannelRegistrar();
+    registrar.register(MODERN, SIMPLE_LEGACY);
+
+    // Two channels cover the modern channel (velocity:test) and the legacy-mapped channel
+    // (legacy:velocitytest). Make sure they're what we expect.
+    assertEquals(ImmutableSet.of(MODERN.getId(), SIMPLE_LEGACY_REMAPPED), registrar.getModernChannelIds());
+    assertEquals(ImmutableSet.of(SIMPLE_LEGACY.getId(), MODERN.getId()), registrar.getLegacyChannelIds());
+  }
+
+  @Test
+  void registerSpecialRewrite() {
+    VelocityChannelRegistrar registrar = new VelocityChannelRegistrar();
+    registrar.register(SPECIAL_REMAP_LEGACY, MODERN_SPECIAL_REMAP);
+
+    // This one, just one channel for the modern case.
+    assertEquals(ImmutableSet.of(MODERN_SPECIAL_REMAP.getId()), registrar.getModernChannelIds());
+    assertEquals(ImmutableSet.of(MODERN_SPECIAL_REMAP.getId(), SPECIAL_REMAP_LEGACY.getId()),
+        registrar.getLegacyChannelIds());
+  }
+
+  @Test
+  void unregister() {
+    VelocityChannelRegistrar registrar = new VelocityChannelRegistrar();
+    registrar.register(MODERN, SIMPLE_LEGACY);
+    registrar.unregister(SIMPLE_LEGACY);
+
+    assertEquals(ImmutableSet.of(MODERN.getId()), registrar.getModernChannelIds());
+    assertEquals(ImmutableSet.of(MODERN.getId()), registrar.getLegacyChannelIds());
+  }
+}