andykuszyk/Performance profiling NUnit tests using Visual Studio 2015.md

## Performance profiling NUnit tests using Visual Studio 2015.md

      
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              Performance profiling NUnit tests using Visual Studio 2015.md
            
          
    Performance Profiling NUnit using Visual Studio 2015

Shortly after learning about the great performance profiling tools built into Visual Studio 2015 (we've just upgraded from 2010, when the best free solution was to use SlimTune [which is awesome for a free, unsupported, open-source tool, but not as awesome as the tools in VS 2015]), I wanted to be able to performance profile slow running unit tests.
Previously, using the afore mentioned SlimTune (https://code.google.com/archive/p/slimtune/), I would run the NUnit gui runner and run the test I was interested in. Although this is still an option using the new VS tools, it doesn't give you a very accurate picture of what's taking the time and, importantly, results in the "hot path" analysis not being useful.
As such, I followed these simple steps to profile my first few tests.
1. Prepare the test for profiling

Nothing special here, I just marked the test for profiling with a unique category so I could pull it out and run it independently from the command line:
  [Test]
  [Category("Profile-Me")
  public void SlowRunningTest_ShouldRunFaster()
  {
    Thread.Sleep(1000);
  }
2. Run the Performance Profiler without the debugger

Next, I fired up the performance profiler from within Visual Studio using:

Debug -> Start Diagnostic Tools without Debugging...

Then:

Change the Target to executable & click Start;
Choose the type of profiling you're after:


Instrumentation won't work here, because you're not profiling an assembly you've built with profiling in;
I generally go with CPU sampling, because this gives you a pretty good idea what's taking the time in your offending test.


On the next screen, you need to choose the executable option again;
Then you need to specify some options for the executable:


The file path will be the path to your installation of the NUnit console runner;
The command line arguments should point the console runner to your assembly or NUnit project, and specifically include your special profiling category.
e.g. C:\Path\To\Tests\MyTestProj.nunit /include: Profile-Me

3. Run the test and analyse the results

From here its easy: just finish the wizard to run the test. Once the test completes, VS will compile a performance report which can be really useful in finding the areas of code that are taking the most time in the test.