MSTest, Microsoft’s unit-testing framework, has the ability to deploy files to a predefined test directory via the [DeploymentItem] attribute. The documentation, however, includes this vague reference:

[DeploymentItem("file1.xml")] Deploys an item named file1.xml located at the RelativeRootPath. The file is deployed to the deployment root directory.
[DeploymentItem("file2.xml", "DataFiles")] Deploys an item named file2.xml located at the RelativeRootPath. The file is deployed to the DataFiles subdirectory of the deployment root directory.

Sounds good, but what is RelativePathRoot? It wasn’t easy to find out, but eventually I came across a post on the MSDN forums, which stated:

… it is simply the directory of the solution containing your test project.

Hmm… This is great, so long as your test project only exists in one solution — or, if in multiple solutions, all solutions are in the same . . .

→ Read More: MSTest, DeploymentItem, and the frustrating RelativePathRoot setting