Simplify getBytes and add tests for it

src/main/java/net/packet/ByteBufInPacket.java

@@ -1,6 +1,7 @@
 package net.packet;
 
 import io.netty.buffer.ByteBuf;
+import io.netty.buffer.ByteBufUtil;
 
 import java.awt.*;
 
@@ -13,10 +14,7 @@ public class ByteBufInPacket implements InPacket {
 
     @Override
     public byte[] getBytes() {
-        byte[] bytes = new byte[byteBuf.readableBytes()];
-        int readerIndex = byteBuf.readerIndex();
-        byteBuf.getBytes(readerIndex, bytes);
-        return bytes;
+        return ByteBufUtil.getBytes(byteBuf);
     }
 
     @Override

src/main/java/net/packet/ByteBufOutPacket.java

@@ -1,6 +1,7 @@
 package net.packet;
 
 import io.netty.buffer.ByteBuf;
+import io.netty.buffer.ByteBufUtil;
 import io.netty.buffer.Unpooled;
 import net.jcip.annotations.NotThreadSafe;
 import net.opcodes.SendOpcode;
@@ -25,10 +26,7 @@ public class ByteBufOutPacket implements OutPacket {
 
     @Override
     public byte[] getBytes() {
-        byte[] bytes = new byte[byteBuf.readableBytes()];
-        int readerIndex = byteBuf.readerIndex();
-        byteBuf.getBytes(readerIndex, bytes);
-        return bytes;
+        return ByteBufUtil.getBytes(byteBuf);
     }
 
     @Override

src/test/java/net/packet/ByteBufInPacketTest.java

@@ -8,6 +8,7 @@ import org.junit.jupiter.api.Test;
 import java.awt.*;
 import java.nio.charset.StandardCharsets;
 
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
 class ByteBufInPacketTest {
@@ -167,4 +168,26 @@ class ByteBufInPacketTest {
         inPacket.seek(5);
         assertEquals(5, inPacket.getPosition());
     }
+
+    @Test
+    void getBytes() {
+        givenWrittenBytes(20, 19, 21, 18, 22);
+
+        byte[] bytes = inPacket.getBytes();
+
+        assertArrayEquals(new byte[]{20, 19, 21, 18, 22}, bytes);
+    }
+
+    @Test
+    void whenGetBytes_shouldBeRepeatable() {
+        givenWrittenBytes(1, 2, 3, 4, 5);
+
+        byte[] bytes = inPacket.getBytes();
+        assertEquals(5, bytes.length);
+
+        byte[] sameBytes = inPacket.getBytes();
+        assertEquals(5, sameBytes.length);
+
+        assertArrayEquals(bytes, sameBytes);
+    }
 }