@isTest
global class NFMHttpCalloutMock implements HttpCalloutMock {
    // 实现这个接口方法
    global HTTPResponse respond(HTTPRequest request) {
        // 创建一个假的回应
        HttpResponse response = new HttpResponse();
        response.setHeader('Content-Type', 'application/json');
        response.setBody('{"expires_in":"2032/12/21","access_token":"32defefe"}');

        response.setStatusCode(200);
        return response; 
    }
}