func deleteSubscription(t *testing.T, fcmConn connector.ResponsiveConnector, userID, gcmID, topic string) {
a := assert.New(t)
u := fmt.Sprintf("http://localhost/fcm/%s/%s/%s", gcmID, userID, topic)
req, err := http.NewRequest(http.MethodDelete, u, nil)
a.NoError(err)
w := httptest.NewRecorder()
fcmConn.ServeHTTP(w, req)
a.Equal(fmt.Sprintf(`{"unsubscribed":"/%s"}`, topic), string(w.Body.Bytes()))
}
