Assets.getBytes returns null in test environment

Question

I'm using the latest Haxe (2.10), NME (3.4.3), and MUnit.

I've written some unit tests that need to fetch bitmap data from SWF symbols. The first step is to actually load the SWF data. To do this, I use NME's getByteArray along with the swf library, like so:

var blah:SWF = new SWF(Assets.getBytes("assets/swf/test.swf"));

The call to Assets.getBytes returns null when I'm running this under MUnit. When running my actual game code, I'm able to get the byte array (and consequentially, instantiate the SWF class).

Am I doing something wrong? What am I missing?

Edit: My directory structure is:

. (root
.\assets
.\assets\*.png (other images)
.\assets\swf\*.swf (SWFs)
.\Source\*.hx (source code)
.\Test\*.hx (tests)