为什么量角器有时 returns 一个承诺，有时 returns 个值？

Question

在official documentation中可以找到以下代码：

var history = element.all(by.repeater('result in memory'));
expect(history.count()).toEqual(2);

不过你也可以找到

element.all(by.repeater('app in userApps')).count().then(function(count) {
    console.log(count);
});

那么为什么 Protractor 有时 returns 一个承诺，有时它 returns 一个值？

Answer 1

history.count() 做了 return 承诺，但 Protractor 改编 Jasmine expect 来理解承诺。

https://github.com/angular/protractor/blob/master/docs/control-flow.md

Answer 2

the protractor folks "patched" jasmine to be promise aware. that is, the expect statement does duck-typing -- if it is a promise, it waits for it to resolve and executes the underlying assertion. if it is any other type, it executes the assertion as it would in any other jasmine world.

source

Answer 3

它总是 returns 一个承诺，只是 expect 被修补以通过将它们添加到 control-flow 来处理它们，以便它们以正确的顺序执行和解析。

为什么量角器有时 returns 一个承诺，有时 returns 个值？

Why does Protractor sometimes returns a promise and sometimes returns a value?

javascript

angularjs

protractor