Have you ever wanted to test the availability of a URL or web page? or check for the presence of content or links on a page? even clicking through a flow of web pages automatically?
Well, these things are not necessarily new concepts or challenges. In fact, in the Application Testing space this is the type of thing we do day in and out.
I have recently been messing around with Selenium and Python web test scripts, and just for kicks wondered if similar things could be achieved using Powershell. Funnily enough, the answer is yes, and quite easily too for anyone familiar with Powershell scripting.
So here are some basics just for fun, to get things going... the magic sauce is in the Invoke-WebRequest cmdlet. Let's check up on this blog's main page as follows by feeding the URL we want to check to the Invoke-WebRequest cmdlet, and assigning the resulting object to a variable called $webpage:
$webpage = Invoke-WebRequest https://blazingtm.com
Nice. Exciting. Maybe not 😃
What can we do with this thing called $webpage you might ask. Well, first let's see what type this object actually is. You can do this calling
$webpage.GetType()
It's a thing called HtmlWebResponseObject. Ok, so not just a simple "webpage", but an object. Well, so it may have associated member properties we can inspect, maybe that could be interesting. We can do this using the following cmdlet
$webpage| Get-Member
The result should look something like follows, listing all member properties and methods for the webpage:
| Name | MemberType | Definition |
| ---- | ---------- | ---------- |
| Dispose | Method | void Dispose(), void IDisposable.Dispose() |
| Equals | Method | bool Equals(System.Object obj) |
| GetHashCode | Method | int GetHashCode() |
| GetType | Method | type GetType() |
| ToString | Method | string ToString() |
| AllElements | Property | Microsoft.PowerShell.Commands.WebCmdletElementCollection |
| BaseResponse | Property | System.Net.WebResponse BaseResponse {get;set;} |
| Content | Property | string Content {get;} |
| Forms | Property | Microsoft.PowerShell.Commands.FormObjectCollection Forms |
| Headers | Property | System.Collections.Generic.Dictionary[string,string] Hea |
| Images | Property | Microsoft.PowerShell.Commands.WebCmdletElementCollection |
| InputFields | Property | Microsoft.PowerShell.Commands.WebCmdletElementCollection |
| Links | Property | Microsoft.PowerShell.Commands.WebCmdletElementCollection |
| ParsedHtml | Property | mshtml.IHTMLDocument2 ParsedHtml {get;} |
| RawContent | Property | string RawContent {get;set;} |
| RawContentLength | Property | long RawContentLength {get;} |
| RawContentStream | Property | System.IO.MemoryStream RawContentStream {get;} |
| Scripts | Property | Microsoft.PowerShell.Commands.WebCmdletElementCollection |
| StatusCode | Property | int StatusCode {get;} |
| StatusDescription | Property | string StatusDescription {get;} |
Let's have a little look at that StatusCode property. To see what it is, use
$statuscode = $webpage.StatusCode
You would have guessed, if we look at the value of $statuscode we will see it's 200. Provided the webpage was available earlier of course. 200 is good when it comes to web page availability.
We can test for this using something along the lines of
if ($statuscode -eq 200) {Write-Output("Brilliant, this page is available :)")}
else {Write-Output("Well, that did not work :(")}
Equally, we might want to make sure the page is not only available (ie a Status Code 200), but that it has a certain content on the page. That is often useful to know to ensure a page has rendered the right results.
This is where the Content property comes in handy. Let's say we wanted to check that the page contains the phrase "Late night musings". Too easy, do this
$webpage.Content.Contains("Late night musings")
Now this will simply return True, or False, depending on whether the phrase is found. Of course you can have further logic on the back of this, but you can see the basics of some interesting web tests evolving here.
That's all for tonight, but following on from this wouldn't it be great if we could script up a whole user flow navigating web pages to test availability of a web site, not just a page. That's however a topic for another time.
Enjoy.
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