Javascript Cypress:Cypress自定义命令'；s的返回值在测试文件中实际返回null

我创建了一个Cypress自定义命令，该命令使用console.log显示值（因此我知道它可以工作）。但是，当我在Cypress测试文件中调用自定义命令时，它返回blank/null

support/commands.js:

Cypress.Commands.add('scanAWSDb', (siteId) => {
 let siteName = null //default it to null
 ... some AWS SDK function which scans the DB and check for corresponding Name of the ID: 12345 ...
 siteName = <new value>
 console.log("Value returned is: " + siteName //This displays the value in the web console for the corresponding ID: 12345, let's say name is Taylor
 return siteName //Expected to return "Taylor" in the test file
})

describe('Display value from the Custom command that scanned the AWS DB', ()=> {
    it('Display value from the Custom command that scanned the AWS DB', () => {
        const siteId = "12345" 
        cy.scanAWSDb(siteId)
            .then((returned_value) => {
                cy.log(returned_value) //This displays a null value so it is not picking up the return value from the custom command which is supposedly Taylor
            })
    })
})

const tableName = 'table1';
let recordId = '';

cy.scanDB(tableName, recordId, $returnValue => {
cy.log($returnValue) //<-- THIS DISPLAYS THE OBJECT BUT I NEED TO CONVERT IT TO STRING SO I CAN DO ASSERTION like this:
//expect($returnValue).to.eq(recordId)
    })

const AWS = require('aws-sdk')
const region = Cypress.env('aws_region')
const accessKeyId = Cypress.env('aws_access_key_id')
const secretAccessKey = Cypress.env('aws_secret_access_key')
const sessionToken = Cypress.env('aws_session_token')

let scannedRecordId = ''

AWS.config.update({region: region})
AWS.config.credentials = new AWS.Credentials(accessKeyId, secretAccessKey, sessionToken)

const docClient = new AWS.DynamoDB.DocumentClient();

export const scanTable = async (tableName, recordId) => {
    const params = {
        TableName: tableName,
        FilterExpression: '#Id = :RecordId',
        ExpressionAttributeNames: {
            '#Id': 'RecordId',
        },
        ExpressionAttributeValues: {
            ':RecordId': recordId // Check if Id is stored in DB
        }
    };

    let scanResults = []; 
    let items
    let index = 0
    do{
        items =  await docClient.scan(params).promise()
        items.Items.forEach((item) => scanResults.push(item))
        params.ExclusiveStartKey  = items.LastEvaluatedKey
        scannedRecordId = JSON.stringify(items.Items[index].Id)
        cy.log('Record successfully found in table: ' + scannedRecordId)
        index += 1 // This may not be required as the assumption is that only a unique record is found
    }while(typeof items.LastEvaluatedKey != "undefined")

    return scannedRecordId;
};

Cypress.Commands.add('scanDB', (tableName, recordId, cb) => {
    const record = scanTable(tableName, recordId)
    cb(record) // Callback function

    // const record = scanTable(tableName, recordId).then(record => { cb(record) }) //This does not work and returns a console error
})

const tableName = 'random-dynamodb-table'
let myId = '12345'
it('Verify if ID is stored in AWS DynamoDB', () => {
cy.scanDB(tableName, myId, $returnValue => {
        cy.log($returnValue)
        cy.log(`Record ID: ${myId} is found in table: ` + $returnValue)
        expect($returnValue).to.deep.eq(myId) //This asserts that the Id is found
        })
    })

=== 更新：

Cypress.Commands.add('scanAWSDb', (siteId) => {
 let siteName = null //default it to null
 ... some AWS SDK function which scans the DB and check for corresponding Name of the ID: 12345 ...
 siteName = <new value>
 console.log("Value returned is: " + siteName //This displays the value in the web console for the corresponding ID: 12345, let's say name is Taylor
 return siteName //Expected to return "Taylor" in the test file
})

describe('Display value from the Custom command that scanned the AWS DB', ()=> {
    it('Display value from the Custom command that scanned the AWS DB', () => {
        const siteId = "12345" 
        cy.scanAWSDb(siteId)
            .then((returned_value) => {
                cy.log(returned_value) //This displays a null value so it is not picking up the return value from the custom command which is supposedly Taylor
            })
    })
})

const tableName = 'table1';
let recordId = '';

cy.scanDB(tableName, recordId, $returnValue => {
cy.log($returnValue) //<-- THIS DISPLAYS THE OBJECT BUT I NEED TO CONVERT IT TO STRING SO I CAN DO ASSERTION like this:
//expect($returnValue).to.eq(recordId)
    })

const AWS = require('aws-sdk')
const region = Cypress.env('aws_region')
const accessKeyId = Cypress.env('aws_access_key_id')
const secretAccessKey = Cypress.env('aws_secret_access_key')
const sessionToken = Cypress.env('aws_session_token')

let scannedRecordId = ''

AWS.config.update({region: region})
AWS.config.credentials = new AWS.Credentials(accessKeyId, secretAccessKey, sessionToken)

const docClient = new AWS.DynamoDB.DocumentClient();

export const scanTable = async (tableName, recordId) => {
    const params = {
        TableName: tableName,
        FilterExpression: '#Id = :RecordId',
        ExpressionAttributeNames: {
            '#Id': 'RecordId',
        },
        ExpressionAttributeValues: {
            ':RecordId': recordId // Check if Id is stored in DB
        }
    };

    let scanResults = []; 
    let items
    let index = 0
    do{
        items =  await docClient.scan(params).promise()
        items.Items.forEach((item) => scanResults.push(item))
        params.ExclusiveStartKey  = items.LastEvaluatedKey
        scannedRecordId = JSON.stringify(items.Items[index].Id)
        cy.log('Record successfully found in table: ' + scannedRecordId)
        index += 1 // This may not be required as the assumption is that only a unique record is found
    }while(typeof items.LastEvaluatedKey != "undefined")

    return scannedRecordId;
};

Cypress.Commands.add('scanDB', (tableName, recordId, cb) => {
    const record = scanTable(tableName, recordId)
    cb(record) // Callback function

    // const record = scanTable(tableName, recordId).then(record => { cb(record) }) //This does not work and returns a console error
})

const tableName = 'random-dynamodb-table'
let myId = '12345'
it('Verify if ID is stored in AWS DynamoDB', () => {
cy.scanDB(tableName, myId, $returnValue => {
        cy.log($returnValue)
        cy.log(`Record ID: ${myId} is found in table: ` + $returnValue)
        expect($returnValue).to.deep.eq(myId) //This asserts that the Id is found
        })
    })

这是有效的，但当尝试执行断言时，它不起作用，因为我无法将对象承诺转换为字符串

测试文件：

Cypress.Commands.add('scanAWSDb', (siteId) => {
 let siteName = null //default it to null
 ... some AWS SDK function which scans the DB and check for corresponding Name of the ID: 12345 ...
 siteName = <new value>
 console.log("Value returned is: " + siteName //This displays the value in the web console for the corresponding ID: 12345, let's say name is Taylor
 return siteName //Expected to return "Taylor" in the test file
})

describe('Display value from the Custom command that scanned the AWS DB', ()=> {
    it('Display value from the Custom command that scanned the AWS DB', () => {
        const siteId = "12345" 
        cy.scanAWSDb(siteId)
            .then((returned_value) => {
                cy.log(returned_value) //This displays a null value so it is not picking up the return value from the custom command which is supposedly Taylor
            })
    })
})

const tableName = 'table1';
let recordId = '';

cy.scanDB(tableName, recordId, $returnValue => {
cy.log($returnValue) //<-- THIS DISPLAYS THE OBJECT BUT I NEED TO CONVERT IT TO STRING SO I CAN DO ASSERTION like this:
//expect($returnValue).to.eq(recordId)
    })

const AWS = require('aws-sdk')
const region = Cypress.env('aws_region')
const accessKeyId = Cypress.env('aws_access_key_id')
const secretAccessKey = Cypress.env('aws_secret_access_key')
const sessionToken = Cypress.env('aws_session_token')

let scannedRecordId = ''

AWS.config.update({region: region})
AWS.config.credentials = new AWS.Credentials(accessKeyId, secretAccessKey, sessionToken)

const docClient = new AWS.DynamoDB.DocumentClient();

export const scanTable = async (tableName, recordId) => {
    const params = {
        TableName: tableName,
        FilterExpression: '#Id = :RecordId',
        ExpressionAttributeNames: {
            '#Id': 'RecordId',
        },
        ExpressionAttributeValues: {
            ':RecordId': recordId // Check if Id is stored in DB
        }
    };

    let scanResults = []; 
    let items
    let index = 0
    do{
        items =  await docClient.scan(params).promise()
        items.Items.forEach((item) => scanResults.push(item))
        params.ExclusiveStartKey  = items.LastEvaluatedKey
        scannedRecordId = JSON.stringify(items.Items[index].Id)
        cy.log('Record successfully found in table: ' + scannedRecordId)
        index += 1 // This may not be required as the assumption is that only a unique record is found
    }while(typeof items.LastEvaluatedKey != "undefined")

    return scannedRecordId;
};

Cypress.Commands.add('scanDB', (tableName, recordId, cb) => {
    const record = scanTable(tableName, recordId)
    cb(record) // Callback function

    // const record = scanTable(tableName, recordId).then(record => { cb(record) }) //This does not work and returns a console error
})

const tableName = 'random-dynamodb-table'
let myId = '12345'
it('Verify if ID is stored in AWS DynamoDB', () => {
cy.scanDB(tableName, myId, $returnValue => {
        cy.log($returnValue)
        cy.log(`Record ID: ${myId} is found in table: ` + $returnValue)
        expect($returnValue).to.deep.eq(myId) //This asserts that the Id is found
        })
    })

awsTest.js文件：

Cypress.Commands.add('scanAWSDb', (siteId) => {
 let siteName = null //default it to null
 ... some AWS SDK function which scans the DB and check for corresponding Name of the ID: 12345 ...
 siteName = <new value>
 console.log("Value returned is: " + siteName //This displays the value in the web console for the corresponding ID: 12345, let's say name is Taylor
 return siteName //Expected to return "Taylor" in the test file
})

describe('Display value from the Custom command that scanned the AWS DB', ()=> {
    it('Display value from the Custom command that scanned the AWS DB', () => {
        const siteId = "12345" 
        cy.scanAWSDb(siteId)
            .then((returned_value) => {
                cy.log(returned_value) //This displays a null value so it is not picking up the return value from the custom command which is supposedly Taylor
            })
    })
})

const tableName = 'table1';
let recordId = '';

cy.scanDB(tableName, recordId, $returnValue => {
cy.log($returnValue) //<-- THIS DISPLAYS THE OBJECT BUT I NEED TO CONVERT IT TO STRING SO I CAN DO ASSERTION like this:
//expect($returnValue).to.eq(recordId)
    })

const AWS = require('aws-sdk')
const region = Cypress.env('aws_region')
const accessKeyId = Cypress.env('aws_access_key_id')
const secretAccessKey = Cypress.env('aws_secret_access_key')
const sessionToken = Cypress.env('aws_session_token')

let scannedRecordId = ''

AWS.config.update({region: region})
AWS.config.credentials = new AWS.Credentials(accessKeyId, secretAccessKey, sessionToken)

const docClient = new AWS.DynamoDB.DocumentClient();

export const scanTable = async (tableName, recordId) => {
    const params = {
        TableName: tableName,
        FilterExpression: '#Id = :RecordId',
        ExpressionAttributeNames: {
            '#Id': 'RecordId',
        },
        ExpressionAttributeValues: {
            ':RecordId': recordId // Check if Id is stored in DB
        }
    };

    let scanResults = []; 
    let items
    let index = 0
    do{
        items =  await docClient.scan(params).promise()
        items.Items.forEach((item) => scanResults.push(item))
        params.ExclusiveStartKey  = items.LastEvaluatedKey
        scannedRecordId = JSON.stringify(items.Items[index].Id)
        cy.log('Record successfully found in table: ' + scannedRecordId)
        index += 1 // This may not be required as the assumption is that only a unique record is found
    }while(typeof items.LastEvaluatedKey != "undefined")

    return scannedRecordId;
};

Cypress.Commands.add('scanDB', (tableName, recordId, cb) => {
    const record = scanTable(tableName, recordId)
    cb(record) // Callback function

    // const record = scanTable(tableName, recordId).then(record => { cb(record) }) //This does not work and returns a console error
})

const tableName = 'random-dynamodb-table'
let myId = '12345'
it('Verify if ID is stored in AWS DynamoDB', () => {
cy.scanDB(tableName, myId, $returnValue => {
        cy.log($returnValue)
        cy.log(`Record ID: ${myId} is found in table: ` + $returnValue)
        expect($returnValue).to.deep.eq(myId) //This asserts that the Id is found
        })
    })

---

如果此

AWS

函数是异步的，您应该像promise那样处理它，因此：

 let siteName = null //default it to null
 ... some AWS SDK function which scans the DB and check for corresponding Name of the ID: 12345 ...
 siteName = <new value>

此外，如果在测试中您只需要读取该值，您可以使用回调而不是承诺：例如

Cypress.Commands.add('scanAWSDb', (siteId, cb) => {
  AWSFunction().then((newValue) => {
    cb(newValue);
  })
})

// test
cy.scanAWSDb(siteId, (returned_value) => {
  cy.log(returned_value)
});

• 更新：

要从对象断言字符串，可以使用

wrap

和

invoke

cypress方法：

scan

函数是异步的，所以您必须这样调用它：

Cypress.Commands.add('scanDB', (tableName, recordId, cb) => {
    const record = scanTable(tableName, recordId).then(record => { cb(record) };
})

---

这个AWS函数是同步的还是异步的？它基于AWS Javascript SDK，所以我假设它是异步的。无论如何，Cypress团队也提供了一个基于此的示例。谢谢你。但是我不能让它工作。我得到未定义的“无法读取属性项”。基本上，我正在尝试调用DynamoDB并使用这里的解决方案返回一个值：。我在我的帖子上提供了一个更新（请参阅更新部分），但我觉得我所做的代码过于结构化。如果你能看一看，那就太好了。我无法在Cypress测试中将对象承诺转换为字符串。由于某些原因，我无法让

等待

或

。然后

工作我添加了更新部分，请让我知道这是否有帮助感谢您在这方面花费的时间。但是，上面的

const-record=scanTable（tableName，recordId）。然后（record=>{cb（record）

不起作用。我在控制台上得到错误：

Uncaught（in-promise）TypeError:无法读取在_callee$

处未定义的属性'recordId'，不尝试使用勺子，但我在Cypress上尝试了各种可能性。按照文档进行承诺、包装和调用，但此异步正在进行中。我需要更多详细信息来解决此问题，完整堆栈跟踪将非常有用。