Advanced Selenium

Selenium test design patterns

PageObject design pattern 

• The public methods represent the services that the page offers
• Try not to expose the internals of the page
• Generally don't make assertions
• Methods return other PageObjects
• Need not represent an entire page
• Different results for the same action are modelled as different methods

Page Factory

• If you use the PageFactory, you can assume that the fields are initialised. If you don't use the PageFactory, then NullPointerExceptions will be thrown if you make the assumption that the fields are already initialised.
• List

  <webelement>

  fields are decorated if and only if they have @FindBy or @FindBys annotation. Default search strategy "by id or name" that works for WebElement fields is hardly suitable for lists because it is rare to have several elements with the same id or name on a page.
• WebElements are evaluated lazily. That is, if you never use a WebElement field in a PageObject, there will never be a call to "findElement" for it.
• The functionality works using dynamic proxies. This means that you shouldn't expect a WebElement to be a particular subclass, even if you know the type of the driver. For example, if you are using the HtmlUnitDriver, you shouldn't expect the WebElement field to be initialised with an instance of HtmlUnitWebElement.