测试另一个Promise的承诺.then()

Question

我试图了解如何在另一个Promise中解决Promise.
我想要实现的步骤如下:

1. User通过UserManager(功能)获取其id
2. 改变它 firstName
3. User通过UserManager(功能)保存到数据库

我正在寻找测试成功UserManager.saveUser(user);回报的回应true.但是我收到了一个错误.

---

UserManagerTest.js

//[...]

it("Should save a user to the database", function () {
    var response = UserManager.getUserByLogin("Foo.Bar@provider.com", "Test")
        .then(function (user) {
            user.firstName = "Macarena";
            return UserManager.saveUser(user);
        })
        .catch((error) => {
            console.log("This error occured: "+error);
            return false;
        })
    return Promise.all([
        expect(response).to.eventually.be.true
    ]);
});

//[...]

---

控制台输出

  1) UserManager Save Should save a user to the database:
     AssertionError: expected undefined to be true
      at node_modules/chai-as-promised/lib/chai-as-promised.js:305:22
      at process._tickCallback (internal/process/next_tick.js:109:7)

---

UserManager.js

static saveUser(user){
    return new Promise((resolve, reject) => {
        pool.getConnection((err, connection)=> {
            if(err) reject(err);

            connection.query("SHOW COLUMNS FROM User;", (error, results, fields) => {
                if(error) reject(error);

                var availableFields = {savable: [], primary: []};
                //[...]
                resolve(availableFields);
            });

            connection.release();
        });
    })
    .then((result) => {
        var usedFields = {savable: [], primary: []};
        //[...]
        return usedFields;
    })
    .then((result) => {
        var sqlParams = [];
        var sql = "UPDATE User SET";
        //[...]
        sql += ";";
        pool.getConnection((err, connection) => {
            if(err) throw err;

            connection.query(sql, sqlParams, (error, results, fields) => {
                if(error) throw error;
                connection.release();
                return results.affectedRows == 1;
            });
        });
    })
    .catch((error) => {
        console.log(error);
        throw error;
    })
};

Answer 1

第二个then((result)=> ...)没有返回任何东西,因此undefined

该return results.affectedRows == 1;是一个lambda里面.它返回那个lambda,而不是周围的`then``

您需要更改语义pool.getConnection以将其从回调更改为Promise.把它包裹在Promise中,解决它并链接它,看起来像

return new Promise((resolve, reject) => {

    pool.getConnection((err, connection) => {
        if(err) {
             //see @robertklep comment
             try { connection.release(); } catch(e) { /* ignore ? */ }
             return reject(err);
        }

        connection.query(sql, sqlParams, (error, results, fields) => {
            if(error) throw error;
            connection.release();
            resolve(results.affectedRows == 1);
        });
    });
})