Add tests for CashShopSurpriseHandler

src/test/java/testutil/Packets.java

@@ -0,0 +1,12 @@
+package testutil;
+
+import io.netty.buffer.Unpooled;
+import net.packet.ByteBufInPacket;
+import net.packet.InPacket;
+
+public class Packets {
+
+    public static InPacket emptyInPacket() {
+        return new ByteBufInPacket(Unpooled.buffer());
+    }
+}