Не работает тест для REST API

testCases := []struct {
    user     string
    password string
    want     string
}{
    {
        user:     "midaef",
        password: "1234",
        want:     "NotAuthorize",
    },
    {
        user:     "[email protected]",
        password: "test1234",
        want:     "OK",
    },
}
for _, test := range testCases {
    reqBody, _ := json.Marshal(map[string]string{
        "user":     test.user,
        "password": test.password,
    })
    req, err := http.NewRequest("POST", "/auth", bytes.NewBuffer(reqBody))
    if err != nil {
        t.Fatal(err)
    }
    req.Header.Set("Content-Type", "application/json")
    rr := httptest.NewRecorder()
    handler := http.HandlerFunc(controllers.Auth)
    handler.ServeHTTP(rr, req)
    if status := rr.Code; status != http.StatusOK {
        t.Errorf("handler returned wrong status code: got %v want %v",
            status, http.StatusOK)
    }
    body, _ := ioutil.ReadAll(rr.Body)
    status, _ := jsonparser.GetString(body, "status")
    if status != test.want {
        t.Errorf("handler returned unexpected body: got %v want %v",
            status, test.want)
    }
}

У меня имеется функция, которая тестирует метод аунтификации. При запуске вылетает паник.

panic: runtime error: invalid memory address or nil pointer dereference [recovered]
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xc0000005 code=0x1 addr=0x1b0 pc=0x749241]

И жалуется вот на эту строчку

handler.ServeHTTP(rr, req)