Advanced WPF automation – memory usage

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Post summary: Highlight eventual memory issue when using Telerik Testing Framework and TestStack White for desktop automation.

Memory is an important aspect. When you have several test cases it is not a problem. But on large projects with many tests memory turn out to be a serious issue.


This post is part of Advanced WPF desktop automation with Telerik Testing Framework and TestStack White series. The sample application can be found on GitHub.


Like every demo on certain technology automating WPF applications looks cool. And also like every technology problems occur when you start to use it on a large scale. Problem with WFP automation with Telerik Testing Framework and TestStack White is the memory. When your tests’ number grows frameworks start to use too much memory. By too much, I mean over 1GB which might not seem a lot but for a single process actually is. Increasing RAM of test machine is an only temporary solution and is not one that can be scaled.

Why so much memory

I have a project with 580 tests and 7300 verification points spread in 50 test classes. I’ve spent lots of hours debugging and profiling with several .NET profiling tools. In the end, all profilers show that a large amount of memory used is in unmanaged objects. So generally there is nothing you can do. It seems like some of the frameworks or both have memory issues and do not free all memory they use.


The solution is pretty simple to suggest but harder to implement – run each test class in the separate process. I’m using a much more enhanced version of NTestsRunner. It is running each test class in separate windows process. Once the test is finished results are serialized in results directory, the process is exited and all memory and object used for this test are released.


The memory could be a crucial factor in an automation project. Be prepared to have a solution for it. At this point, I’m not planning to put running tests in a separate process in NTestsRunner. If there is demand it is a pretty easy task to do it.

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