golang test exit status -1 and shows nothing - testing

Question

Recently I've been working on a Restful app in golang, strange things happened when I try to write tests in different subdirectories. My project structure is:
├── handlers/
│ ├── defs.go
│ ├── hello_test.go
│ ├── hello.go
├── server/
│ ├── codes.go
│ ├── middlewares_test.go
│ ├── middlewares.go
├── utility/
│ ├── auth.go
│ ├── auth_test.go
All files in handlers/ are declared "package handlers", all files in server/ are declared "package server", and so on. When I run go test in utility/ and handlers/ everything is fine. But if I run go test in server/, it returns me nothing but just:
[likejun#localhost server]$ go test
exit status 1
FAIL server_golang/server 0.003s
It seems that it exits with a code 1 before even run, could someone tells me why this happened? Thank you, I've been spent the whole afternoon on it.
the code in middleware_test.go
package server
import (
"io"
"net/http"
"net/http/httptest"
"testing"
)
func TestHello(t *testing.T) {
req, err := http.NewRequest(http.MethodGet, "/", nil)
if err != nil {
t.Fatal(err)
}
rec := httptest.NewRecorder()
func(w http.ResponseWriter, r *http.Request) {
w.WriteHeader(http.StatusOK)
w.Header().Set("Content-Type", "application/json")
io.WriteString(w, `{"hello": "world"}`)
}(rec, req)
if status := rec.Code; status != http.StatusOK {
t.Errorf("handler returned wrong status code: got %d want %d", status, http.StatusOK)
}
if rec.Header().Get("Content-Type") != "application/json" {
t.Errorf("handler returned wrong content type header: got %s want %s", rec.Header().Get("Content-Type"), "application/json")
}
expected := `{"hello": "world"}`
if rec.Body.String() != expected {
t.Errorf("handler returned unexpected body: got %s want %s", rec.Body.String(), expected)
}
}