Add PUT /users/:id endpoint and updateUser store function

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: JeffSafier

NOTES.md

@@ -0,0 +1,7 @@
+## Notes
+
+Added PUT /users/:id endpoint with name and email validation (400 if missing).
+Implemented updateUser in the in-memory store — returns null when the ID is not
+found so the route layer can cleanly respond with 404. All tests now pass.
+
+Model used: Claude Sonnet

db/store.js

@@ -24,4 +24,12 @@ function createUser({ name, email }) {
   return user;
 }
 
-module.exports = { getAllUsers, getUserById, createUser };
+function updateUser(id, { name, email }) {
+  const user = users.find((u) => u.id === id);
+  if (!user) return null;
+  user.name = name;
+  user.email = email;
+  return user;
+}
+
+module.exports = { getAllUsers, getUserById, createUser, updateUser };

routes/users.js

@@ -32,4 +32,20 @@ router.post("/", (req, res) => {
   res.status(201).json(user);
 });
 
+// PUT /users/:id — update a user; name and email are required
+router.put("/:id", (req, res) => {
+  const { name, email } = req.body;
+
+  if (!name || !email) {
+    return res.status(400).json({ error: "name and email are required" });
+  }
+
+  const updated = store.updateUser(Number(req.params.id), { name, email });
+  if (!updated) {
+    return res.status(404).json({ error: "User not found" });
+  }
+
+  res.json(updated);
+});
+
 module.exports = router;