Excluding assemblies from Code Coverage

I regularly run Visual Studio’s code coverage analysis to get an idea of my test coverage, but there’s a lot of code in the project that’s auto generated code and I wanted to turn off the code coverage metrics for these assemblies.

I could look to add the ExcludeFromCodeCoverage attribute as outlined in a previous post “How to exclude code from code coverage” but this is a little laborious when you have many types to add this to and also, in some cases, I do not have control of the code gen tools to apply such attributes after every regeneration of the code – so not exactly ideal.

There is a solution as described in the post Customizing Code Coverage Analysis which allows us to create solution wide file to exclude assemblies from code coverage, I’m going to summarize the steps to create the file here…

Creating the .runsettings file

  • Select your solution in the solution explorer and then right mouse click and select Add | New Item…
  • Select XML File and change the name to your solution name with the .runsettings extension (the name needn’t be the solution name but it’s a good starting point).
  • Now I’ve taken the following from Customizing Code Coverage Analysis but reduced it to the bare minimum, I would suggest you refer to the aforementioned post for a more complete file if you need to use the extra features. 
    <?xml version="1.0" encoding="utf-8"?>
<!-- File name extension must be .runsettings -->
<RunSettings>
  <DataCollectionRunSettings>
    <DataCollectors>
      <DataCollector friendlyName="Code Coverage" uri="datacollector://Microsoft/CodeCoverage/2.0" assemblyQualifiedName="Microsoft.VisualStudio.Coverage.DynamicCoverageDataCollector, Microsoft.VisualStudio.TraceCollector, Version=11.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a">
        <Configuration>
          <CodeCoverage>
            <!-- Match assembly file paths: -->
            <ModulePaths>
              <Include>
                <ModulePath>.*\.dll$</ModulePath>
                <!--<ModulePath>.*\.exe$</ModulePath>-->
              </Include>
              <Exclude>
                <ModulePath>.*AutoGenerated.dll</ModulePath>
                <ModulePath>.*Tests.dll</ModulePath>
              </Exclude>
            </ModulePaths>

            <!-- We recommend you do not change the following values: -->
            <UseVerifiableInstrumentation>True</UseVerifiableInstrumentation>
            <AllowLowIntegrityProcesses>True</AllowLowIntegrityProcesses>
            <CollectFromChildProcesses>True</CollectFromChildProcesses>
            <CollectAspDotNet>False</CollectAspDotNet>

          </CodeCoverage>
        </Configuration>
      </DataCollector>
    </DataCollectors>
  </DataCollectionRunSettings>
</RunSettings>

    In the above code you’ll note I’ve included all dll’s using the Regular Expression .*\.dll$ but then gone on to exclude a couple of assemblies.

    Note: If I do NOT include the .* in the exclude module paths I found that the analysis still included those files. So just typing the correct name of the assembly on it’s own failed and I needed the .* for this to work.

  • The include happens first and then the exclude takes place. Hence we can use wildcards in the include then exclude certain assemblies explicitly.
  • Before we can actually use the runsettings we need to tell Visual Studio to use the runsettings. So before you test your changes you need to select the Test menu item then Test Settings followed by Select Test Settings File. Select your runsettings file.

    Note: you can tick/untick the selected file via the same menu option to turn on/off the runsettings file being used

Now I can run code coverage across my code and will see only the assemblies that matter to me.