c# - Problems with DeploymentItem attribute

Question

I'm currently maintaining an "old" system written in C#.net, removing some obsolete features and doing some refactoring. Thanks god, the previous guy wrote some unit tests (MSTests). I quite comfortable with JUnit tests, but didn't do yet much with MSTests.

The test methods have a DeploymentItem attribute, specifying a text file which is parsed by the business logic method that is being tested and a 2nd DeploymentItem where just a path has been specified containing a bunch of TIF files that have to be deployed too.

[TestMethod()]
[DeploymentItem(@"filesvalidvalid_entries.txt")]
[DeploymentItem(@"filesif")]
public void ExistsTifTest()
{
   ...
}

The tests worked before, but now I had to change the names of the TIF files contained in the filesif directory. According to a rule, the TIF filenames have to match a certain pattern which is also checked by the ExistsTifTest() method. Now I had to change the filenames in order to adapt them to the new requirements and suddently the TIF files are no more being deployed as before.

Can someone give me a hint why this happens or what may be the cause? The same thing happens also if I add a new text-file say "my2ndTest.txt" beside the "valid_entries.txt" in the filesvalid directory with the according DeploymentItem attribute on the test method. The file doesn't get deployed?

I got the images now deployed by defining the deployment path directly in the testrunconfig, but I'd like to understand why these things happen or why for instance my new file "my2ndTest.txt" doesn't get deployed while the others do.

Answer 1

DeploymentItem is a bit of a mess.

Each file in your solution will have a "Copy To Output Folder" setting in VS.NET. You need this to be "Copy Always" (or similar) in order to get the files into the output folder.

Check that you've got this set for the new files. If you don't have this set then the files won't get copied to the output folder, and then they can't be deployed from the output folder to the folder where MSTest does it stuff.

Personally, if I have files that I need for my unit tests I've found that embedding those files as resources into an assembly, and having that assembly "unpack" itself during the tests is a more predictable way of doing things. YMMV.

note: These comments are based upon my experience with VS2010. Comments to my answer would suggest that this is not problem with VS2012. I still stand by comments that using embedded resources involves less "magic" and, for me, makes the "arrange" stage of my unit tests much more explicit.