# t/Data.pm
package t::Data;

our @cases = (
  {
    label => "3 pairs",
    input => ( 'a' .. 'f' ),
  },
  # etc...
);

1;

##</code><code>##

# t/42_somefunctionality.t
use Test::More; # no plan here!
use t::Data;

my $tests_per_case = 13;

plan tests => $test_per_case * @t::Data::cases;

for my $case ( @t::Data::cases ) {
  # 13 tests here for each case
}

##</code><code>##

# t/DBM/Deep/Test.pm
package t::DBM::Deep::Test;
use base 'Test::Class';
use Test::More;

my @cases = (
  # all test data here
);

sub startup :Test(startup) {
  my $self = shift;
  $self->{cases} = \@cases;
}

1;

##</code><code>##

# t/DBM/Deep/Feature1.pm
use base 't::DBM::Deep::Test';
use Test::More;

sub a_simple_test :Tests {
  my $self = shift;
  for my $c ( @{ $self->{cases} } ) {
    # tests here
  }
}

1;

##</code><code>##

# runtests.t

use t::DBM::Deep::Feature1;
use t::DBM::Deep::Feature2;
# etc...

Test::Class->runtests();