Added Jest for testing both front and backend

server/presenters/user.js

@@ -0,0 +1,15 @@
+const presentUser = (ctx, user) => {
+  ctx.cache.set(user.id, user);
+
+  return new Promise(async (resolve, _reject) => {
+    const data = {
+      id: user.id,
+      name: user.name,
+      username: user.username,
+      avatarUrl: user.slackData.image_192,
+    };
+    resolve(data);
+  });
+};
+
+export default presentUser;