The unit tests run in a separate deployment folder and not in the folder where they were created. The separation helps to ensure better test runs and more accurate test results. During a test run, Visual Studio performs several steps, and one of them is to copy all necessary files to the deployment folder. The deployment folder can be local or remote. A remote deployment folder is used when working with test rigs.
The files are copied in a specific order to the deployment folder. Files that are copied later, overwrites files copied earlier if they have the same name. Visual Studio copy the files in the following order:
1) The files that comprise the test.
2) Binaries that are instrumented, for example files that are used in code coverage analysis.
3) Files specified in the run configuration.
4) Dependent files, for example dependent assemblies and config files.
5) Deployment items specified per test.