title: Running a data driven unit test off more than one input file
body: <p>Background: In our project, we have a bunch of xml files that define tests that are loaded into a report generator. Since we want to make sure our tests stay accurate, we have data driven unit tests set up to test that the xml input produces the same output. This is currently held in a large excel spreadsheet, and works great with Visual Studio's data driven unit tests. But, this leads to problems because often more than one developer will be working on tests, and they will need to get the spreadsheet to add the unit tests. If another developer has the spreadsheet, then they are stalled waiting on it to get checked back in since VS can't merge the excel file. In addition, we are wanting to switch to git, and this approach won't work well there either due to the lack of locking on checkouts and inability to merge binary files.</p>
  
  <p>So, we are trying to switch to having a separate file for each individual test's set of unit tests in a folder. Then, when the unit tests are run, we load up all the files in the folder and run the test data in each of the files. This way, when a developer makes a new test, they just have to add a new file for the unit tests, instead of having to add an entry to a central file.</p>
  
  <p>The data format is going to be the same across all the files, so really, even concatenating them together should work. But, I'm trying to do this and retain the data driven behavior where each row in the test data is equivalent to one test in the output; they all pass or fail/produce output messages separately. </p>
  
  <p><strong>Is it possible to run a data driven unit test off of multiple files? If so, can we still retain the 'one row == one test' style output in the results?</strong></p>