In the spirit of TMTOWTDI you could also use IO::File to create a temporary file, redirect STDIN to the temporary file, do your stuff, seek back to the start and slurp up the output into a scalar for testing as normal.

The skip2.t test in Test::Class uses this method.

One of the advantages is that IO::File is core so you don't have to muck around with other modules.

I did write a Test::Output module (download Test-Output-0.01.tar.gz) that allowed you to do things like:

  output_is     { hello() } "hello world\n", STDOUT, "hello world";
  output_isnt   { hello() } "goodbye",       STDOUT, "not goodbye";
  output_unlike { hello() } qr/bye/,         STDOUT, "didn't print bye
+";
  output_like   { hello() } qr/hello/,       STDOUT, "printed hello";
  like(Test::Output->last, qr/world/, "... and world");
[download]

... but I'm not entirely happy with the API so have not distributed it yet... feedback welcome :-)