javascript - 有人可以解释以下 Angular 测试代码中调用的 evaluate() 和 dragAndDrop() 是什么吗？

Question

以下代码用于使用 Protractor 测试 angular-Gridster 应用程序的拖放方向。

我对下面的一些函数调用不熟悉，有人能解释一下 evaluate() 的意义吗——API 定义太困惑了，还有 dragAndDrop()？ -- 在任何地方都找不到这个函数

describe('DragAndDrop Test', function () {

require('jasmine-expect');

beforeAll(function () {
    context = new Context();
    context.get();
    browser.waitForAngular();
    browser.driver.manage().window().maximize();

});

it('should drag and drop a tile', function () {

    //target is where we are dragging the box to.  Box is the Box
    var target = { x: 400, y: 400 };
    var box = element(by.css('.ng-scope.gridster-item'));

    //scope is going to hold the scope variables that tell us where the box is located
    //see the documentation for angular gridster on github for info on scope variable
    //get the standardItems Scope
    box.evaluate('standardItems').then(function (scope) {

        //make sure the box we are using is in column 0 and Row 0
        expect(scope[0].col).toEqual(0);
        expect(scope[0].row).toEqual(0);
    });

    //drag and drop the box somewhere else.
    browser.actions().dragAndDrop(box, target).perform();
    browser.waitForAngular();

    //get the updated scope
    box.evaluate('standardItems').then(function (scope) {

        //test to see that the box was actually moved to column and row 2, better test
        expect(scope[0].col).toEqual(2);
        expect(scope[0].row).toEqual(2);
    });
    //this is to test the pixel location which is not the best
    box.getLocation().then(function (location) {
        expect(location.x).toEqual(476);
    });
});
});

var Context = function () {

//load the website
this.get = function () {
    browser.get('https://rawgit.com/ManifestWebDesign/angular-gridster/master/index.html#/main');
};
};

Answer 1

evaluate()将在您调用它的元素的范围内评估表达式。当您需要访问范围内的特定变量时很有用:

Evaluates the input as if it were on the scope of the current element.

---

dragAndDrop()是一个“浏览器操作”，继承自 WebDriverJS(请记住， Protractor 构建在 WebDriverJS 之上):

Convenience function for performing a "drag and drop" manuever. The target element may be moved to the location of another element, or by an offset (in pixels).