Design a perl Moose class to facilitate testing

Question

I am trying to design a class in perl. I am using Mooose. I am using an outside module (let's name it PITA::Parser.

has _parser => (
    is => 'ro',
    isa => 'object',
    builder => _create_parser_object);

#other members here

sub _create_parser_object {
    #simplified code
    return PITA::Parser->new();    
}

sub BUILD {
    my $self = shift;
    $self->_values($self->load_and_validate_data());
}

sub _load_and_validate_data {
    my $values_href;
    foreach $key (@key_names) {
        $values_href->{$key} = $self->_parser->get_value();

    #code to validate the values

    return $values_href;
}

I want to mock out the PITA::Parser object. This object looks for a specific file (during new) that is not in my test folder, but rather in the environment where my code will be deployed. So, I am trying to mock it out as such:

my $mock_parser = Test::MockObject->new();
$mock_parser->mock('new', sub {});
$mock_parser->mock('get_value', sub {});

Then I want to create an object of my class

my $my_class_object(_parser => $mock_parser);

However, this does not work, I get an error that get_value can not be located by Test::MockObject.

Answer 1

You can use Test::MockObject to mock the parser object and pass it when creating your own object.

my $mock = Test::MockObject->new();
$mock->mock( 'frobnicate',
    sub { return 'file that is not part of test environment' } );

my $obj = Your::Class->new(parser => $mock);
ok( $obj->load_and_validate_data );

It will create an object that has a method frobnicate. When called in your load_and_validate_data, it will return the controlled values you want it to return. There's a bunch of other stuff you can do with it. I suggest you take a look at the documentation.