path := filepath.Join(t.TempDir(), "log.txt")

prefix := "logprefix"

f, err := LogToFile(path, prefix)

if err != nil {

t.Error(err)

}

log.SetFlags(log.Lmsgprefix)

log.Println("some test log")

if err := f.Close(); err != nil {

t.Error(err)

}

out, err := os.ReadFile(path)

if err != nil {

t.Error(err)

}

if string(out) != prefix+" some test log\n" {

t.Fatalf("wrong log msg: %q", string(out))

}