diff --git a/common/player.test.ts b/common/player.test.ts
new file mode 100644
index 0000000000000000000000000000000000000000..7cfc37f4a20d270ef49f795f8d4a40c09ff01288
--- /dev/null
+++ b/common/player.test.ts
@@ -0,0 +1,21 @@
+import { io, Socket } from "socket.io-client";
+import Player from "./Player";
+import { Sushi } from "./Ressources";
+(global as any).Image = function () {};
+
+describe("sizeIncrease", () => {
+  it("should increase by 0.5", function () {
+    const p = new Player(0, 0, 20, "goku", 1, 1, "test");
+    const sushis: Sushi[] = [new Sushi(0, 0, 5)];
+    const socket: Socket = io();
+    p.eatSushi(sushis, socket);
+    expect(p.radius).toBe(20.5);
+  });
+  it("should change form every 80", function () {
+    const p = new Player(0, 0, 79.5, "goku", 1, 1, "test");
+    const sushis: Sushi[] = [new Sushi(0, 0, 5)];
+    const socket: Socket = io();
+    p.eatSushi(sushis, socket);
+    expect(p.image.src).toBe("/images/character/goku/goku2.png");
+  });
+});
diff --git a/jest.config.cjs b/jest.config.cjs
new file mode 100644
index 0000000000000000000000000000000000000000..b413e106db66e6c7150b76da0fc542e797db4034
--- /dev/null
+++ b/jest.config.cjs
@@ -0,0 +1,5 @@
+/** @type {import('ts-jest').JestConfigWithTsJest} */
+module.exports = {
+  preset: 'ts-jest',
+  testEnvironment: 'node',
+};
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