Open your solution in VS2010
Under Tools menu, you will find the Holmes Statistical Debugging menu option. Click this menu option and then choose Configuration Holmes instrumentation. This step open a windows that lists all projects in the solution.
Re-build the solution. Open your NUnit and run the tests.
Open Holmes analysis window from Tools – Holmes Statistical Debugging – Holmes Window menu option and launch a new analysis.
In the new analysis window, select the test framework type as NUnit, the test project path (path to the NUnit test project file), the project ("Local Solution" for non-TFS projects), the build and the test run that you would like to analyze. Optionally, you can select any of the previous builds as a baseline build.
Now click the Analyze button. This will start a new analysis. This might take a while depending on the number of test cases in the test run.
Once the analysis finishes, Holmes reports a list of code paths that may be causing the test failures (if any). Each row in the window corresponds to a potential root cause. Also displayed is the source file and the method containing the root cause.
Double click on any of the rows to view the code path in the Visual Studio editor. The code paths are highlighted in red. Holmes associates and sorts the suspicious code paths with a confidence score (indicated by the red bar next to each code path). The confidence indicates the degree of correlation between the code path and test failures. Holmes also associates each code path with a set of failures that are explained by the code path.