Video Recording C# WebDriver Tests in TestPipe
The title is a little misleading because you can use the technique below to do a screen capture of anything happening on the screen and not just WebDriver tests. Yet, TestPipe does use C# WebDriver out the box so we will be recording these types of tests.
So, we want to add video recording tests to TestPipe. At first I thought this would be very difficult, but after finding Microsoft Expression Encoder SDK it became a lot easier. I was even able to find other people that have used this SDK which made a decision to move forward with this a little easier to take on.
First, I read the Working with Screen Capture section of the Overview of the Expression Encoder SDK. From this I learned that I needed to create an instance of ScreenCaptureJob. The question is, where do I create it?
In TestPipe we have a ScenarioSession class that holds state of various things while a test scenario runs and it makes sense to expose this new functionality there because we want to be able to control video recording within the context of individual test scenarios. Do we add a new property on the session or should it be a new property on the IBrowser interface. We already have a TakeScreenshot method on IBrowser. Yet, I don’t think it is a good fit on the browser interface because there is a bit of setup that needs to take place for ScreenCaptureJob that is out of scope for a browser and I don’t want to muddy up the API more than it already is.
When we setup a scenario we want to allow setup of the ScreenCaptureJob based on configuration for a feature and/or a scenario. We define features and scenarios in a text file, currently using Gherkin, and we store data used in feature and scenario tests in a JSON file. So, we have to configure video recording in the Gherkin, JSON or both.
Do we keep all recordings or only failing recordings? What if we want to keep only failing, but from time to time we need non-failing recordings for some reason? Do we overwrite old recordings or store in unique folders or filenames?
To trigger the recording we could use tags. If an @Video tag is present on the scenario or feature, record the scenario(s) and only keep the recording if the scenario fails. If the @Debug tag is present on the Feature or the Scenario, keep the recordings even if they don’t fail.
We can create a unique folder for the recordings so that we can store videos of multiple runs of the same scenario. We may want to think about how we clean these up, but we may have enough file clean up in other processes. We will just have to watch hard drive space in production use.
So, we have a strategy to automatically configure recording. Now, we have to implement it in a way that also allows manual configuration just in case we want to hard wire video recording in a test.
So, I found our seam to make the changes for video recording. In our RunnerBase class we have methods to setup and teardown a scenario. It is there that we will make the change to configure, start, stop, and delete video recordings.
Now to implement. First I download the encoder from http://www.microsoft.com/en-us/download/details.aspx?id=27870. This will have to be installed on every server that will run tests so I create a Powershell script to install it. It would be nice to also do a Chocolatey package, but that is overkill for me because I am not using Chocolatey on my servers right not. You can create your own automated installer by extracting the setup file from the download then creating a Powershell script to run
to quietly install. I believe you can use the -x parameter to uninstall, but I didn’t test this yet. (Assuming msiexe command line options are used https://msdn.microsoft.com/en-us/library/aa367988(v=vs.85).aspx)
With the encoder installed we have access to the DLLs that we need to work with. In VisualStudio I add a reference to the extensions for Microsoft.Expression.Encoder, Microsoft.Expression.Encoder.Api2, Microsoft.Expression.Encoder.Types, and Microsoft.Expression.Encoder.Utilities. Not sure if I need all these, but they were added by the installer so I will keep them for now.
From here I can add a using
and implement recording based on the sample code, updating to fit TestPipe standards.
One caveat is the encoder outputs some kind of Microsoft proprietary video format xesc. I thought about collecting all the videos that are kept at the end of a test run and run some kind of parallel task to convert them to a more portable format. In the end, I just left it alone. This is a new feature and only my team will be looking at the videos and everyone has Windows Media Player that can play the format.
I won’t write more on implementation details because I am boring myself, but if you want to check it out you can view it on GitHub (RunnerBase is where we use the recorder and you should be able to figure out the rest). One interesting twist is we implemented Expression Encoder behind an interface so that it isn’t requirement to use TestPipe. If we didn’t do this, you wouldn’t be able to build or use TestPipe without first installing the dependent encoder.
So, TestPipe comes out the box with a dummy implementation of the interface that won’t actually do the recordings. If you want to capture actual recording you can use the TestPipe.MSVideoRecorder plug-in or implement the IVideoRecorder interface on another screen capture program to enable video recording of tests. Right now TestPipe.MSVideoRecorder, is included in the TestPipe solution, but it is not set to build automatically. When we make changes we set it to build and manually move the binary to the folder we have configured to hold the video recorder plug-ins. Eventually, we will move it to a separate repository and create a NuGet package, but I’m tired.
Overview of the Expression Encoder SDK – https://msdn.microsoft.com/en-us/library/Gg602440(v=Expression.40).aspx
Road to screen recording in webdriver with C# – http://roadtoautomation.blogspot.com/2013/07/road-to-screen-recording-in-webdriver.html
Record video of your Selenium Tests – https://blog.testingbot.com/2011/12/19/record-video-of-your-selenium-tests
If you are running tests on Windows Server you have to add the feature User Interfaces and Infrastructure > Desktop Experience to install missing dependencies required by Microsoft Expression Encoder.