username := GetUser()
if username != "dummyUser" {
  t.Errorf("unexpected username: got %s, want %s", username, "dummyUser")
}
используйте более элегантный и лаконичный подход:

if got, want := GetUser(), "dummyUser"; got != want {
  t.Errorf("username=%s, want=%s", got, want)
}

package main

import (
    "context"
    "log"
    "net/http"
    "os"
    "os/signal"
    "time"
)

func main() {
    mux := http.NewServeMux()
    mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
        time.Sleep(3 * time.Second)
        w.Write([]byte("Request done"))
    })

    server := &http.Server{
        Addr:    ":8080",
        Handler: mux,
    }

    go func() {
        log.Println("Server starting on :8080")
        if err := server.ListenAndServe(); err != nil && err != http.ErrServerClosed {
            log.Fatalf("ListenAndServe error: %v", err)
        }
    }()

    stop := make(chan os.Signal, 1)
    signal.Notify(stop, os.Interrupt, os.Kill)

    <-stop
    log.Println("Shutting down server...")

    ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
    defer cancel()

    if err := server.Shutdown(ctx); err != nil {
        log.Fatalf("Forced shutdown: %v", err)
    }

    log.Println("Server exited gracefully")
}

type A struct {
    B bool   // 1 byte (+7 padding)
    I int64  // 8 bytes
} 
// Sizeof(A) = 16

type B struct {
    I int64  // 8 bytes
    B bool   // 1 byte (+7 padding)
} 
// Sizeof(B) = 16

type KeyGood struct {
    ID   int
    Name string
} 
// сравнимо, работает как ключ

type KeyBad struct {
    Data []byte
} 
// ошибка: []byte несравнимый тип

type KeyArr struct { Digest [16]byte }


Преобразовать срез в строку:

key := string(digestBytes)
m := map[string]string{key: "value"}