I second Juerd's argument.

There are a few testing functions I like to use which wrap around the basic ok() function. I put them in a Test::Special module which sits under the t/ directory and which is brought into each file in the test suite simply by:

  use lib ("./t");
  use Test::Special;
[download]

See, for example, List::Compare.

OTOH, Test::Deep is by now quite a large set of modules and it might be a bit much to include it in your distribution solely for the purpose of testing.