Protractor page object definition not working as expected - protractor

Question

I apologize for the slightly vague title, I'm not sure how exactly to word this.
I have my Page Object which, with one exception, works perfectly. Here's the excerpt:
module.exports = function(){
this.facilityList = element(by.name('facility')).all(by.tagName('option'));
this.randomFacility = element(by.name('facility')).all(by.tagName('option')).count().then(function(numberOfItems) {
var rnum = parseInt(Math.random() * numberOfItems);
return rnum;
}).then(function(randomNumber) {
element(by.name('facility')).all(by.tagName('option')).get(randomNumber)
});
}
I can access and use facilityList just fine. But then I realized that I'm almost always doing the same thing to facilityList so why don't I just create another line to make it choose a random one. So I create randomFacility using the code from the main conf.js.
It didn't work. The error I see displayed is:
Failed: Error while waiting for Protractor to sync with the page: "both angularJS testability and angular testability are undefined. This could be either because this is a non-angular page or because your test involves client-side navigation, which can interfere with Protractor's bootstrapping. See http://git.io/v4gXM for details"
I'm confused. Is this saying I can't do all that processing in the page object to get the random one or do I simply have to manipulate facilityList in the conf.js and be done with it?

Answer 1

You nee to know the mechanism about how protractor to find element. Protractor only to start find element from page when protractor's action API be called, like getText(), click(), count() etc.
So when you define variable to represent certain element on page, when Nodejs execute this line, protractor won't to start find element from page:
// page object login.page.js
module.exports = function LoginPage(){
this.sumbitButton = element(by.css('#submit'));
this.countName = element.all(by.css('.username')).count();
}
// use page object in conf.js
var LoginPage = require('./login.page.js');
var loginPage = new Loginpage();
When Nodejs execute line var loginPage = new Loginpage();, all lines in function LoginPage will be executed.
When execute the first line, protractor not to find element from current open page,
When execute the second line, protractor will find element from current open page, But at this time point, protractor is possible to launching browser with a blank page, the target page have not been opened or navigated to.
To fix your problem, you need to define randomFacility as class's Method, rather than Property:
module.exports = function() {
this.facilityList = element(by.name('facility')).all(by.tagName('option'));
this.randomFacility = function() {
return element(by.name('facility'))
.all(by.tagName('option')).count()
.then(function(numberOfItems) {
console.log('count: '+numberOfItems);
var rnum = parseInt(Math.random() * numberOfItems);
console.log('random index: '+rnum);
return rnum;
})
.then(function(randomNumber) {
console.log('argument randomNumber: '+randomNumber);
return element(by.name('facility'))
.all(by.tagName('option')).get(randomNumber)
});
}
};
// how to use
pageObject.randomFacility().then(function(ele){
return ele.click();
});