cypress

cypress和selenium一样都是基于浏览器的自动化测试工具，两者各有特点。cypress最大的特点就是环境非常简单，支持js语言，并且GUI非常好看。

selenium则是历史悠久，工业规范，多语言支持，尤其是支持Python。

安装与运行

npm i --save cypress
npx cypress open

框架与语法简介

在当前目录运行cypress open之后会生成下图这样的目录结构（也可以在当前仓库看到。）

有一个cypress.json是存储基础的配置的，例如常用来存储host，exclude test等。

有一个cypress目录，其中有个integration目录是用来存储集成测试的test case脚本的，所有的js文件必须以.spec.js来结尾才会被cypress识别为测试脚本

测试脚本的语法可以参考提供的todo.spec.js如下，第一行是必须的，然后所有的测试都在一个describe函数的回调中运行，因为有第一行的引入，在当前js上下文中是可以使用cypress提供的函数和变量的，

例如beforeEach函数就是在接下来每个it测试场景之前都会执行的操作。

cy.visit是当前浏览器指定访问一个url。

cy.get类似jQuery的选取dom，得到一个或多个dom元素，dom元素支持的常见方法：

• should('have.text', 'xxx') 判断内部文字
• click() 点击
• type('xx') 输入文字

cy.get.contains用于辅助锁定dom元素。

核心秘诀

• Cypress.$等于jquery的$，是内嵌了jQuery。但是不要visit之后上来就用，因为页面还没加载出来。
• cy的函数基本都是异步的，在context第一行定义一个getText的异步函数，然后在visit之后先getText一下。
• 本目录下cypress项目cypress/integration/1-getting-started/youdao.spec.js展示了如何进行爬虫，非常实用。

let jq = Cypress.$;
let getText = async (node) => {
  return await new Promise((t,c) => {
    node.invoke('text').then(t)
  })
}

/// <reference types="cypress" />

// Welcome to Cypress!
//
// This spec file contains a variety of sample tests
// for a todo list app that are designed to demonstrate
// the power of writing tests in Cypress.
//
// To learn more about how Cypress works and
// what makes it such an awesome testing tool,
// please read our getting started guide:
// https://on.cypress.io/introduction-to-cypress

context('example to-do app', () => {
  beforeEach(() => {
    // Cypress starts out with a blank slate for each test
    // so we must tell it to visit our website with the `cy.visit()` command.
    // Since we want to visit the same URL at the start of all our tests,
    // we include it in our beforeEach function so that it runs before each test
    cy.visit('https://example.cypress.io/todo')
  })

  it('displays two todo items by default', () => {
    // We use the `cy.get()` command to get all elements that match the selector.
    // Then, we use `should` to assert that there are two matched items,
    // which are the two default items.
    cy.get('.todo-list li').should('have.length', 2)

    // We can go even further and check that the default todos each contain
    // the correct text. We use the `first` and `last` functions
    // to get just the first and last matched elements individually,
    // and then perform an assertion with `should`.
    cy.get('.todo-list li').first().should('have.text', 'Pay electric bill')
    cy.get('.todo-list li').last().should('have.text', 'Walk the dog')
  })

  it('can add new todo items', () => {
    // We'll store our item text in a variable so we can reuse it
    const newItem = 'Feed the cat'

    // Let's get the input element and use the `type` command to
    // input our new list item. After typing the content of our item,
    // we need to type the enter key as well in order to submit the input.
    // This input has a data-test attribute so we'll use that to select the
    // element in accordance with best practices:
    // https://on.cypress.io/selecting-elements
    cy.get('[data-test=new-todo]').type(`${newItem}{enter}`)

    // Now that we've typed our new item, let's check that it actually was added to the list.
    // Since it's the newest item, it should exist as the last element in the list.
    // In addition, with the two default items, we should have a total of 3 elements in the list.
    // Since assertions yield the element that was asserted on,
    // we can chain both of these assertions together into a single statement.
    cy.get('.todo-list li')
      .should('have.length', 3)
      .last()
      .should('have.text', newItem)
  })

  it('can check off an item as completed', () => {
    // In addition to using the `get` command to get an element by selector,
    // we can also use the `contains` command to get an element by its contents.
    // However, this will yield the <label>, which is lowest-level element that contains the text.
    // In order to check the item, we'll find the <input> element for this <label>
    // by traversing up the dom to the parent element. From there, we can `find`
    // the child checkbox <input> element and use the `check` command to check it.
    cy.contains('Pay electric bill')
      .parent()
      .find('input[type=checkbox]')
      .check()

    // Now that we've checked the button, we can go ahead and make sure
    // that the list element is now marked as completed.
    // Again we'll use `contains` to find the <label> element and then use the `parents` command
    // to traverse multiple levels up the dom until we find the corresponding <li> element.
    // Once we get that element, we can assert that it has the completed class.
    cy.contains('Pay electric bill')
      .parents('li')
      .should('have.class', 'completed')
  })

  context('with a checked task', () => {
    beforeEach(() => {
      // We'll take the command we used above to check off an element
      // Since we want to perform multiple tests that start with checking
      // one element, we put it in the beforeEach hook
      // so that it runs at the start of every test.
      cy.contains('Pay electric bill')
        .parent()
        .find('input[type=checkbox]')
        .check()
    })

    it('can filter for uncompleted tasks', () => {
      // We'll click on the "active" button in order to
      // display only incomplete items
      cy.contains('Active').click()

      // After filtering, we can assert that there is only the one
      // incomplete item in the list.
      cy.get('.todo-list li')
        .should('have.length', 1)
        .first()
        .should('have.text', 'Walk the dog')

      // For good measure, let's also assert that the task we checked off
      // does not exist on the page.
      cy.contains('Pay electric bill').should('not.exist')
    })

    it('can filter for completed tasks', () => {
      // We can perform similar steps as the test above to ensure
      // that only completed tasks are shown
      cy.contains('Completed').click()

      cy.get('.todo-list li')
        .should('have.length', 1)
        .first()
        .should('have.text', 'Pay electric bill')

      cy.contains('Walk the dog').should('not.exist')
    })

    it('can delete all completed tasks', () => {
      // First, let's click the "Clear completed" button
      // `contains` is actually serving two purposes here.
      // First, it's ensuring that the button exists within the dom.
      // This button only appears when at least one task is checked
      // so this command is implicitly verifying that it does exist.
      // Second, it selects the button so we can click it.
      cy.contains('Clear completed').click()

      // Then we can make sure that there is only one element
      // in the list and our element does not exist
      cy.get('.todo-list li')
        .should('have.length', 1)
        .should('not.have.text', 'Pay electric bill')

      // Finally, make sure that the clear button no longer exists.
      cy.contains('Clear completed').should('not.exist')
    })
  })
})