<p> This is what I expect will become the first of a series of posts where I detail some of the solutions I&#39;ve arrived at, based on the test programs that I&#39;ve written to work through the problem.</p> <p> The situation I was running into was this:</p> <p> I was writing tests for some parsing code. The output of the parse was a nested data structure. Some (well, many) parts of the data structure were optional. One in particular was giving me a hard time, though—it was a default being set from a dynamic value being passed into the parser. Obviously I had to get that same dynamic value into the test data as well, in order for them to match.</p>