Recursively compare the content of two arbitrary Perl data structures

Objective

To recursively compare the content of two arbitrary Perl data structures

Scenario

Suppose you are writing a test harness for a Perl function called get_credentials which returns a hash ref. You know exactly what value it should return and wish to test whether it has done so.

Method

You can compare Perl data structures using the Data::Compare module. First the module must be installed. On Debian-based systems it is located in the package libdata-compare-perl:

apt-get install libdata-compare-perl

The next step is to load the module. The function that you are most likely to need, called Compare, is imported by default:

use Data::Compare;

You should now be able to compare any two data structures by passing them to the Compare function:

my $returned_data = get_credentials;
my $expected_data = {username=>'user',password=>'xyzzy'};
if (!Compare($returned_data,$expected_data)) {
	die 'unexpected response from get_credentials';
}

The value returned by Compare is 1 if the values match or 0 if they do not.

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