Item Store API Lab

Build a small in-memory REST-style API for items. All testing is done with net/http/httptest — no real server needed.

Data type

Use a package-level map as storage:

Endpoints

Register all routes on an http.NewServeMux().

GET /items

• Marshal the full contents of store as a JSON array
• Respond with status 200

GET /items/{id}

• Use strings.TrimPrefix to extract the ID from the path (e.g. strings.TrimPrefix(r.URL.Path, "/items/"))
• If found, respond with the item JSON and status 200
• If not found, respond with body "not found" and status 404

POST /items

• Decode the JSON request body into an Item
• Store it in store by its ID field
• Respond with status 201 (Created)

Middleware

Write withContentType(next http.Handler) http.Handler that sets the Content-Type: application/json header on every response before delegating to the inner handler.

Wrap the entire mux with this middleware.

Testing in main

Use httptest.NewRecorder and httptest.NewRequest to exercise all three endpoints:

1. POST {"id":"1","name":"Widget","price":9.99} to /items — expect status 201
2. GET /items — expect the response body to contain "Widget"
3. GET /items/1 — expect status 200 and "id":"1" in the body
4. GET /items/999 — expect status 404

Print each status code and relevant body excerpt so the output makes the results visible.