Hello.

I'm trying to test my DBI based application with the help of Test::MockDBI module. And--I don't get it.

I have the following code:

→ File dblibtry.t

#!/usr/bin/env perl
use strict;
use warnings;
use diagnostics;
use Readonly;

use Test::MockDBI;
use Test::Simple tests => 10;

use DbLibTry;
# Testing DbLibTry Perl module

Readonly my %RET_VALS => (
    1 => {
        name  => 'fgv3df1fv5f3',
        time  => '32:20',
        album => 5120,
        order => 2,
    },
    2 => {
        name  => 'fdgetre14w6e46we4',
        time  => '2:00',
        album => 89,
        order => 5,
    },
);

my $dblibtry = DbLibTry->new;
my $mock_dbi = Test::MockDBI::get_instance;
my %song;

$mock_dbi->set_retval(
    method => 'get_all_songs',
    retval => \%RET_VALS
);

ok(defined $dblibtry, "Defined $dblibtry");
ok($dblibtry->isa('DbLibTry'), 'ISA');

ok($dblibtry->can('connect'), 'Method ->connect() exists');
ok($dblibtry->can('disconnect'), 'Method ->disconnect() exists');
ok($dblibtry->can('get_all_songs'), 'Method ->get_all_songs() exists')
+;

ok($dblibtry->connect == 1, 'Connected');

ok(%song = %{$dblibtry->get_all_songs});

ok($dblibtry->disconnect == 1, 'Disconnected');

ok($song{2}->{order} == 2);
ok($song{1}->{time} eq '2:00');
[download]

→ File DbLibTry.pm

package DbLibTry;

use strict;
use warnings;
use diagnostics;
use DBI;

sub new {
    return bless {}, shift;
}

sub connect {
    my $self = shift;

    $self->{dbh} = DBI->connect(
        "DBI:SQLite:dbname=songdb.sqlite3",
        q{},
        q{},
        {RaiseError => 1}
    ) or return $DBI::errstr;
    return 1;
}

sub disconnect {
    my $self = shift;

    $self->{dbh}->disconnect;
    return 1;
}

sub get_all_songs {
    my $self = shift;

    my $sth = $self->{dbh}->prepare('select * from songs;');
    my $rv  = $sth->execute or return $DBI::errstr;
    return $DBI::errstr if ($rv < 0);
    my %hash;
    while (my @row = $sth->fetchrow_array) {
        $hash{$row[0]} = {
            name  => $row[1],
            # Name of song
            time  => $row[2],
            # Total time of song
            album => $row[3],
            # Album ID for song
            order => $row[4],
            # Order of song in album
        };
    }
    return \%hash;
}

1;
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→ File dblibtry.pl

#!/usr/bin/env perl
use strict;
use warnings;
use diagnostics;
use feature qw(say);
use Data::Dumper;
use DbLibTry;

my $dblibtry = DbLibTry->new;
$dblibtry->connect;
my %hash = %{$dblibtry->get_all_songs};
$dblibtry->disconnect;
say Dumper %hash;
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If I run the .pl file, everything is fine, but if I run the test, I got the following output:

$ perl dblibtry.t
1..10
ok 1 - Defined DbLibTry=HASH(0x8847860)
ok 2 - ISA
ok 3 - Method ->connect() exists
ok 4 - Method ->disconnect() exists
ok 5 - Method ->get_all_songs() exists
ok 6 - Connected
Can't use an undefined value as a HASH reference at dblibtry.t line 46
+ (#1)
    (F) A value used as either a hard reference or a symbolic referenc
+e must
    be a defined value.  This helps to delurk some insidious errors.
    
Uncaught exception from user code:
    Can't use an undefined value as a HASH reference at dblibtry.t lin
+e 46.
# Looks like you planned 10 tests but ran 6.
# Looks like your test exited with 255 just after 6.
$
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What am I doing wrong?