Test::Deep 0.096

Test::Deep is a Perl module for extremely flexible deep comparison.

SYNOPSIS

use Test::More tests => $Num_Tests;
use Test::Deep;

cmp_deeply(
$actual_horrible_nested_data_structure,
$expected_horrible_nested_data_structure,
"got the right horrible nested data structure"
);

cmp_deeply(
$object,
methods(name => "John", phone => "55378008"),
"object methods ok"
);

cmp_deeply(
@array,
[$hash1, $hash2, ignore(
"first 2 elements are as expected, ignoring 3"
);

cmp_deeply(
$object,
noclass({value => 5}),
"object looks ok, not checking its class"
);

cmp_deeply(
@result,
bag(a, b, {key => [1, 2]}),
"array has the 3 things we wanted in some order"
);

If you dont know anything about automated testing in Perl then you should probably read about Test::Simple and Test::More before preceding. Test::Deep uses the Test::Builder framework.

Test::Deep gives you very flexible ways to check that the result you got is the result you were expecting. At its simplest it compares two structures by going through each level, ensuring that the values match, that arrays and hashes have the same elements and that references are blessed into the correct class. It also handles circular data structures without getting caught in an infinite loop.
Where it becomes more interesting is in allowing you to do something besides simple exact comparisons. With strings, the eq operator checks that 2 strings are exactly equal but sometimes thats not what you want. When you dont know exactly what the string should be but you do know some things about how it should look, eq is no good and you must use pattern matching instead. Test::Deep provides pattern matching for complex data structures.