在测试函数中运行ListenAndServe（）时，端口没有关闭，该如何解决？

Question

When I call http.ListenAndServe() in a test function the port does NOT close even after the tests have finished and the process has terminated. So the next time I run the tests I get the error "ListenAndServe: listen tcp :8080: bind: address already in use".

This does not happen when I run my program normally through main().

func TestIndex(t *testing.T) {
  handle := handlers.ServeAndHandle("8080")
  req, _ := http.NewRequest("GET", "", nil)
  w := httptest.NewRecorder()
  handle.ServeHTTP(w, req)
  if w.Code != http.StatusOK {
      t.Errorf("Home page didn't return %v", http.StatusOK)
  }
}
// this is just a wrapper function of ListenAndServe. m is of type handler
func ServeAndHandle(port string) http.Handler {
  m := &mux{}
  err := http.ListenAndServe(":"+port, m) // set listen port
  if err != nil {
      log.Fatal("ListenAndServe: ", err)
  }
  return m
}

Answer 1

You can use NewUnstartedServer to create a instance, start it manually then defer closing it at the end of the test. Something along the lines:

...
ts := httptest.NewUnstartedServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {  
    fmt.Fprintln(w, "Hello world")
}))

l, _ := net.Listen("tcp", URL)
ts.Listener = l
ts.Start()
defer ts.Close()

res, err := http.Get(URL)  
if err != nil {
  log.Fatal(err)
} 
...