I watched the tutorial DIY Golang Web Server: No Dependencies Needed! from Flo Woelki and want to create some test classes for it.

Goal:

• Add a user to userCache and test if the number of user in userCache is increased by 1

Steps:

• Start the server with go run main.go – see source code here
• Open a second terminal and run the test go test -run Test_PostUser – this should add a user to the userCache
• Open http://127.0.0.1:8080/userlist in the browser and check if the new users was added to the list

Problem

After running the test with go test -run Test_PostUser the func Test_PostUser should have added another user to the list. But if i open http://127.0.0.1:8080/userlist in the browser it shows only 2 users

• Expected: userlist has 3 users after running go test -run Test_PostUser
• Got: userlist has only 2 users (the initial users that are created a start)

Main func

This is the code inside main

func main() {

    // Initialize users
    userCache[1] = User{Name: "John"}
    userCache[2] = User{Name: "Mandy"}

    mux := http.NewServeMux()
    mux.HandleFunc("POST /users", createUser)
    mux.HandleFunc("GET /users/{id}", getUser) // https://youtu.be/eqvDSkuBihs?t=844
    mux.HandleFunc("GET /userlist", getUserlist)

    fmt.Println("Server listening to 8080")
    http.ListenAndServe(":8080", mux)
}

Func to create a user

// https://youtu.be/eqvDSkuBihs?t=541
func createUser(w http.ResponseWriter, r *http.Request) {
    var user User
    err := json.NewDecoder(r.Body).Decode(&user) // pass memory address of created user struct
    if err != nil {
        http.Error(w, err.Error(), http.StatusBadRequest)
        return
    }

    if user.Name == "" {
        http.Error(w, "Name is required", http.StatusBadRequest)
        return
    }

    // without mutex this would not be thread safe
    // writes and reads could happen at same time --> race condition
    cacheMutex.Lock()
    userCache[len(userCache)+1] = user
    cacheMutex.Unlock()

    w.WriteHeader(http.StatusNoContent)
}

Test func

My test method that should add a user to usercache

func Test_PostUser(t *testing.T) {

    // Define the URL and the data to which the POST request will be sent
    url := "http://127.0.0.1:8080/users"
    data := User{Name: "Max"}

    // Marshal the data to JSON
    jsonData, err := json.Marshal(data)
    if err != nil {
        t.Errorf("Error marshalling JSON: %v", err)
    }

    // Create a new POST request
    req, err := http.NewRequest(http.MethodPost, url, bytes.NewBuffer(jsonData))
    if err != nil {
        t.Errorf("Error creating request: %v", err)
    }

    // Set the content type header to application/json
    req.Header.Set("Content-Type", "application/json")

    // Create an HTTP client and send the request
    client := &http.Client{}
    resp, err := client.Do(req)
    if err != nil {
        t.Errorf("Error sending request: %v", err)
    }
    defer resp.Body.Close()
}

Question

• What am i missing?
• Why is the user not added to the usercache or why is the user not part of GET /userlist?

See full source code here