Question

I am writing automation scripts using WATIR and WATIN. Watir has something called page checkers, which are code snippets that run on each page load. Is there something similar in WATIN ? I want a piece of code to run on each page load. Generally this is used to check for page errors or page loading images.

Answer 1

It is not really that easy to tell when page loads. I quickly googled about that page checkers in Watir, that you mentioned and found an article about page checkers in Watir. See first comment bellow the article. AFAIK it’s really similar in WatiN.

Unfortunately, I don’t see any similar functionality in WatiN (no event is fired after internal call to WaitForComplete. The easiest thing you could do is to subclass eg. IE class:

class MyIE : IE
{
    public MyIE(string url) : base(url) { } //TODO: add constructors

    public override void WaitForComplete(int waitForCompleteTimeOut)
    {
        base.WaitForComplete(waitForCompleteTimeOut);
        Console.WriteLine("Page has been loaded");
    }
}

However, the situation will be similar to described in mentioned comment (runs a lot more regularly than just page load).

I think that better approach would be using Page class from WatiN library. It is well documented. Example for watin.org webpage:

var ie = new MyIE("http://watin.org/");

var homePage = ie.Page<HomePage>();
Console.WriteLine(homePage.FirstFeature);
homePage.DocumentationLink.Click();

var documentationPage = ie.Page<DocumentationPage>();
Console.WriteLine(documentationPage.FAQLink.Url);

To run that code you need following classes:

abstract class WatiNBasePage : Page
{
    [FindBy(Id = "header")]
    public Div HeaderDiv { get; set; }

    public Link HomeLink { get { return HeaderDiv.Link(Find.ByText("Home")); } }

    public Link DocumentationLink { get { return HeaderDiv.Link(Find.ByText("Documentation")); } }

    protected override void InitializeContents()
    {
        base.InitializeContents();
        VerifyDocumentProperties(UnverifiedDocument, errorMessage => { throw new Exception(errorMessage); }); //TODO: modify if needed
    }

    protected override void VerifyDocumentProperties(Document document, Page.ErrorReporter errorReporter)
    {
        base.VerifyDocumentProperties(document, errorReporter);
        if (!HomeLink.Exists)
            errorReporter("HomeLink not exists");
        //TODO: more checks here
    }
}

class HomePage : WatiNBasePage
{
    [FindBy(Id = "features")]
    public Table FeatureTable { get; set; }

    public string FirstFeature { get { return FeatureTable.Span(Find.First()).Text; } }
}

class DocumentationPage : WatiNBasePage
{
    [FindBy(Text = "Frequently Asked Questions")]
    public Link FAQLink { get; set; }
}

Basically you need to implement VerifyDocumentProperties. Above code will check if HomeLink exists, but maybe you would like to check if DocumentationLink exists etc. The second thing is to modify call to VerifyDocumentProperties. Now, if verification fails, Exception will be thrown after calling ie.Page<T>() (where T is a subclass of WatinBaseClass).

In my opinion, even if you don’t need to use “page checkers”, using Page class is still really useful and clarifies the code, so I really recommend using it. I regret that I haven’t discovered it when I was starting work with WatiN.