diff --git a/source/_test/core.py b/source/_test/core.py
new file mode 100644
index 0000000..6b41e66
--- /dev/null
+++ b/source/_test/core.py
@@ -0,0 +1,12 @@
+import unittest
+
+
+class TestCore(unittest.TestCase):
+    # TODO
+
+    def test_something(self):
+        self.assertEqual(True, False)  # add assertion here
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/source/_test/network.py b/source/_test/network.py
new file mode 100644
index 0000000..a04ee5a
--- /dev/null
+++ b/source/_test/network.py
@@ -0,0 +1,53 @@
+import socket
+import string
+import unittest
+import random
+from threading import Thread
+from typing import Optional
+
+from source.network.packet import PacketChat
+
+
+class TestNetwork(unittest.TestCase):
+    PORT: int = 54231
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+        # Prépare deux sockets pour simuler les packets
+        self.co_client = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        self.so_server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+
+        self.so_server.bind(("", self.PORT))
+        self.so_server.listen()
+        self.co_server: Optional[socket.socket] = None
+
+        def connect_server(): self.co_server, _ = self.so_server.accept()
+        def connect_client(): self.co_client.connect(("127.0.0.1", self.PORT))
+
+        thread_server = Thread(target=connect_server)
+        thread_client = Thread(target=connect_client)
+        thread_server.start()
+        thread_client.start()
+        thread_server.join()
+        thread_client.join()
+
+    def __del__(self):
+        self.co_client.close()
+        self.so_server.close()
+
+    def test_packet_chat(self):
+        for _ in range(100):
+            message = "".join(random.choice(string.printable) for _ in range(random.randint(1, 100)))
+
+            PacketChat(message).send_data_connection(self.co_server)
+            packet_chat = PacketChat.from_connection(self.co_client)
+
+            self.assertEqual(message, packet_chat.message)
+
+    # TODO: autre type de packets
+    # TODO: type de packet générique
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/source/_test/position.py b/source/_test/position.py
new file mode 100644
index 0000000..d6a4142
--- /dev/null
+++ b/source/_test/position.py
@@ -0,0 +1,76 @@
+import unittest
+
+from source.gui.position import *
+from source.gui.scene.abc import Scene
+from source.gui.widget.abc import BoxWidget
+from source.gui.window import Window
+
+
+class TestWindow(Window):  # NOQA
+    def __init__(self, *args, **kwargs):
+        super().__init__(width=1920, height=1080, visible=False, *args, **kwargs)
+
+
+class TestScene(Scene):
+    def __init__(self, window: "Window", **kwargs):
+        super().__init__(window=window, **kwargs)
+
+
+class TestBoxWidget(BoxWidget):
+    def __init__(self, scene: "Scene"):
+        super().__init__(x=100, y=200, width=150, height=175, scene=scene)
+
+
+window = TestWindow()
+scene = TestScene(window)
+widget = TestBoxWidget(scene)
+
+
+class TestPosition(unittest.TestCase):
+    def test_unit_px(self):
+        for value in range(1, 500):
+            self.assertEqual((value*px)(widget), value)
+
+    def test_unit_vw(self):
+        for value in range(1, 200):
+            self.assertEqual((value*vw)(widget), int(window.width * (value / 100)))
+
+    def test_unit_vh(self):
+        for value in range(1, 200):
+            self.assertEqual((value*vh)(widget), int(window.height * (value / 100)))
+
+    def test_unit_ww(self):
+        for value in range(1, 200):
+            self.assertEqual((value*ww)(widget), int(widget.width * (value / 100)))
+
+    def test_unit_wh(self):
+        for value in range(1, 200):
+            self.assertEqual((value * wh)(widget), int(widget.height * (value / 100)))
+
+    def test_unit_add(self):
+        for value_px in range(1, 100):
+            for value_vw in range(1, 100):
+                self.assertEqual(
+                    (value_px*px + value_vw*vw)(widget),
+                    value_px + int(window.width * (value_vw / 100))
+                )
+
+    def test_unit_sub(self):
+        for value_px in range(1, 100):
+            for value_vw in range(1, 100):
+                self.assertEqual(
+                    (value_px * px - value_vw * vw)(widget),
+                    value_px - int(window.width * (value_vw / 100))
+                )
+
+    def test_unit_rsub(self):
+        for value_px in range(1, 100):
+            for value_vw in range(1, 100):
+                self.assertEqual(
+                    (value_vw * vw - value_px * px)(widget),
+                    int(window.width * (value_vw / 100)) - value_px
+                )
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/source/_test/utils.py b/source/_test/utils.py
new file mode 100644
index 0000000..8a39626
--- /dev/null
+++ b/source/_test/utils.py
@@ -0,0 +1,135 @@
+import unittest
+import numpy as np
+
+from source.utils import dict_filter, dict_filter_prefix, dict_add_prefix, copy_array_offset
+
+
+class TestDict(unittest.TestCase):
+    def test_dict_filter(self):
+        self.assertEqual(
+            dict_filter(
+                lambda key, value: key.startswith("valeur"),
+                {"valeur1": 1, "valeur2": 2, "clé1": None}
+            ),
+            {"valeur1": 1, "valeur2": 2}
+        )
+
+        self.assertEqual(
+            dict_filter(
+                lambda key, value: key.startswith("test"),
+                {"test_AB": 1, "TEST_AB": 2.5, "début": 3}
+            ),
+            {"test_AB": 1}
+        )
+
+        self.assertEqual(
+            dict_filter(
+                lambda key, value: key.startswith("test"),
+                {"input_AB": 1, "TEST_AB": 2.5, "début": 3}
+            ),
+            {}
+        )
+
+    def test_dict_filter_prefix(self):
+        self.assertEqual(
+            dict_filter_prefix(
+                "valeur",
+                {"valeur1": 1, "valeur2": 2, "clé1": None}
+            ),
+            {"1": 1, "2": 2}
+        )
+
+        self.assertEqual(
+            dict_filter_prefix(
+                "test_",
+                {"test_AB": 1, "TEST_AB": 2.5, "début": 3}
+            ),
+            {"AB": 1}
+        )
+
+        self.assertEqual(
+            dict_filter_prefix(
+                "test",
+                {"input_AB": 1, "TEST_AB": 2.5, "début": 3}
+            ),
+            {}
+        )
+
+    def test_dict_add_prefix(self):
+        self.assertEqual(
+            dict_add_prefix(
+                "valeur",
+                {"1": 1, "2": 2, "A": None}
+            ),
+            {"valeur1": 1, "valeur2": 2, "valeurA": None}
+        )
+
+        self.assertEqual(
+            dict_add_prefix(
+                "test_",
+                {"AB": 1, "2": 2.5, "fin": 3}
+            ),
+            {"test_AB": 1, "test_2": 2.5, "test_fin": 3}
+        )
+
+        self.assertEqual(
+            dict_add_prefix(
+                "test",
+                {"A": 1, "B": 2.5, "E": 3}
+            ),
+            {"testA": 1, "testB": 2.5, "testE": 3}
+        )
+
+
+class TestMatrice(unittest.TestCase):
+    def test_copy_array_offset(self):
+        src = np.array([
+            [1, 2, 3, 4],
+            [5, 6, 7, 8]
+        ])
+        dst = np.array([
+            [2, 5, 1, 3, 5, 0],
+            [2, 3, 4, 1, 4, 5],
+            [0, 1, 4, 0, 3, 9],
+            [4, 0, 9, 5, 2, 8]
+        ])
+
+        copy_dst = dst.copy()
+        copy_array_offset(src=src, dst=copy_dst, offset=(1, 2))
+
+        self.assertTrue(
+            (copy_dst == np.array([
+                [2, 5, 1, 3, 5, 0],
+                [2, 3, 4, 1, 4, 5],
+                [0, 1, 2, 3, 4, 9],
+                [4, 5, 6, 7, 8, 8]
+            ])).all()
+        )
+
+        copy_dst = dst.copy()
+        copy_array_offset(src=src, dst=copy_dst, offset=(2, 2))
+
+        self.assertTrue(
+            (copy_dst == np.array([
+                [2, 5, 1, 3, 5, 0],
+                [2, 3, 4, 1, 4, 5],
+                [0, 1, 1, 2, 3, 4],
+                [4, 0, 5, 6, 7, 8]
+            ])).all()
+        )
+
+        copy_dst = dst.copy()
+        copy_array_offset(src=src, dst=copy_dst, offset=(1, 0))
+
+        self.assertTrue(
+            (copy_dst == np.array([
+                [2, 1, 2, 3, 4, 0],
+                [2, 5, 6, 7, 8, 5],
+                [0, 1, 4, 0, 3, 9],
+                [4, 0, 9, 5, 2, 8]
+            ])).all()
+        )
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/source/network/game_network.py b/source/network/game_network.py
index 6e65b1e..e51d965 100644
--- a/source/network/game_network.py
+++ b/source/network/game_network.py
@@ -1,8 +1,6 @@
-import builtins
 import socket
-from typing import Type, Callable
+from typing import Type, Callable, TYPE_CHECKING
 
-from source.gui.scene import Game
 from source.network.packet.abc import Packet
 from source.network import packet
 
@@ -10,10 +8,14 @@ from source.utils import StoppableThread
 from source.utils.thread import in_pyglet_context
 
 
+if TYPE_CHECKING:
+    from source.gui.scene import Game
+
+
 def game_network(
         thread: "StoppableThread",
         connection: socket.socket,
-        game_scene: Game,
+        game_scene: "Game",
 ):
     """
     Run the networking to make the game work and react with the other player
diff --git a/source/utils/__init__.py b/source/utils/__init__.py
index 5b1effa..6c7efd4 100644
--- a/source/utils/__init__.py
+++ b/source/utils/__init__.py
@@ -1,5 +1,5 @@
 from .matrice import copy_array_offset
 from .bbox import in_bbox
-from .dict import dict_filter, dict_filter_prefix
+from .dict import dict_filter, dict_filter_prefix, dict_add_prefix
 from .thread import StoppableThread
 from .path import path_ctime_str