Unit testing 无法使用Mocha和Chai在sequelize中对API进行单元测试

您好，我是新来的

单元

测试。我目前正在为一个API进行TDD单元测试。但是，在使用运行单元测试时，出现以下错误：

 msg: 'TypeError: Cannot read property \'firstName\' of undefined' } to not exist

我为API编写的

单元测试如下所示：

describe('createUser', function () {
it('should create a User', function (done) {
    var email_Id = "xyz@gmail.com";
    var firstName = "xyx";
    var values = JSON.stringify({
        body: {
            email_Id: email_Id,
            firstName: firstName
        }
    });
    user.createUser(values, function (err, response) {
        expect(response).should.be.an(object);
        expect(err).to.be.null;
    });
    done();
   });
});

createUser: function (req, res) {
    var param = req.body;
    var firstName = param.firstName;
    var email_Id = param.email_Id;
    db.sequelize.sync().then(function () {
        user.create(param).then(function (response) {
            // return a Success Response in JSON format

        }).catch(function (err) {
           // return an Error Response in JSON format
        });
    });
  }
}

我的
API
如下：

describe('createUser', function () {
it('should create a User', function (done) {
    var email_Id = "xyz@gmail.com";
    var firstName = "xyx";
    var values = JSON.stringify({
        body: {
            email_Id: email_Id,
            firstName: firstName
        }
    });
    user.createUser(values, function (err, response) {
        expect(response).should.be.an(object);
        expect(err).to.be.null;
    });
    done();
   });
});

createUser: function (req, res) {
    var param = req.body;
    var firstName = param.firstName;
    var email_Id = param.email_Id;
    db.sequelize.sync().then(function () {
        user.create(param).then(function (response) {
            // return a Success Response in JSON format

        }).catch(function (err) {
           // return an Error Response in JSON format
        });
    });
  }
}

有人能帮我解释一下为什么会出现这个错误吗？
req.body未定义