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

Question

In the official documentation you can find the following code:

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

But you can also find examples using promises

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

So why does Protractor sometimes returns a promise and sometimes it returns a value?

Answer 1

history.count() does return a promise, but Protractor adapts Jasmine expect to understand promises.

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

Answer 2

It always returns a promise, it's just that expect is patched to handle them by adding them to the control-flow so that they get executed and resolved in the proper order.

Answer 3

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.

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