In an effort to reduce the workload of some unit tests, and create a

more standardized set of testing functions, TestCase has gained two

new functions:


precreate_tempfiles() will generate a specified number of temporary

   filenames (using make_tempfile()), spy on make_tempfile, and then

   return that list. The list of temp filenames are also returned to the

   caller. This allows the caller to pre-generate some command

   executions or spy operations that may need to know those temp

   filenames.


assertDiffEqual(), which compares two diffs, ensuring both are

   bytestrings and comparing the lines of each to ensure correct content

   (or to make diffing of mismatches clear).


Along with this, maxDiff was set to a high number, allowing assertion

failures that compare strings or lists to provide more useful

information, rather than truncating prematurely.
kgb 6.1 is now required, in order to support the spy operation

functionality needed by precreate_tempfiles().

Successfully made use of the new functionality in some upcoming unit tests.