Test::More usage to test functions that die

mkirank has asked for the wisdom of the Perl Monks concerning the following question:

I have a subroutine f1 in a Class

Package A;

use Carp;

sub new {
 ...
}

sub f1 {
my $param1 = shift;
my $param2 = shift;
my $param3 = shift;

croak '- parameter1 required' unless $param1;
if ((!$param2) && $param3 eq 'X') {
    croak '- parameter2 required' ;
}

some code here;
}
[download]

I use Test::More to test this sub . Here is what i have used


use Test::More qw(no_plan);

my $n = 1;
BEGIN {
    use_ok('A');
}
$n++;

my $a = new A;

isa_ok( $a,"A");
$n++;

eval {
    $a->f1( ) };

print "ok $n";
print "\t\tno arguements passed\n";
if ( $@) {
    diag ( "$@\n" );
}
$n++;
[download]

my question is When we do not pass parameter to the f1 then it must die,
I use eval to do this in the test script ,
Is this how i should test this function ) or is there any other option in Test::more (which is the best way)

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Re: Test::More usage to test functions that die by tomhukins (Curate) on Dec 08, 2004 at 14:23 UTC
It's not part of Test::More itself, but Test::Exception's `dies_ok` method should help: `dies_ok { $a->f1 } 'passing no arguments to f1 dies';` [download] For more information about the different testing modules available, see the Testing Modules section of Perl Quality Assurance Projects.	[reply] [d/l] [select]
Re: Test::More usage to test functions that die by herveus (Prior) on Dec 08, 2004 at 11:44 UTC
Howdy! eval sets $@ if the code dies, so something like `ok($@, "no args passed");` [download] will directly test that condition. yours, Michael	[reply] [d/l]
Re: Test::More usage to test functions that die by stvn (Monsignor) on Dec 08, 2004 at 15:31 UTC
If you don't want to use Test::Exception (which I highly recommend), then the easist Test::More way of doing this would be this: `eval { $a->f1( ) }; ok($@, '... an exception has been thrown'); like($@, qr/\- parameter1 required/, '... and it is the correct except +ion');` [download] I would also recomment when you test the function with parameters, to also wrap it inside an eval, like this: `eval { $a->f1("paramter" ) }; ok(!$@, '... no exception has been thrown');` [download] This is the idea behind the `lives_ok` function in Test::Exception. -stvn	[reply] [d/l] [select]
Re: Test::More usage to test functions that die by trammell (Priest) on Dec 08, 2004 at 14:55 UTC
One way is to overload `croak()` inside your test, then make sure that calling your function calls `croak()` under the right circumstances. E.g.: `# (pseudocode) our $croakcount; sub main::croak { $croakcount++; } myfunc(my $badoptions); is ($croakcount, 1, "myfunc() calls croak()");` [download]	[reply] [d/l] [select]
Re^2: Test::More usage to test functions that die by stvn (Monsignor) on Dec 08, 2004 at 15:21 UTC
This wont work unless all your code is in `main::` (and even then its a delicate situation at best) `#!/usr/bin/perl sub main::croak { print "I croaked"; } { package Test; use Carp; sub myfunc { croak("I am dying"); } } eval { Test::myfunc(); }; print $@ if $@; *myfunc = \&Test::myfunc; eval { myfunc(); }; print $@ if $@; __OUTPUT__ I am dying at test.pl line 18 I am dying at test.pl line 26` [download] However, what you are talking about is not unlike the ideas behind MockObjects, see Test::MockObject and Test::MockModule for more info. -stvn	[reply] [d/l] [select]
Re^3: Test::More usage to test functions that die by trammell (Priest) on Dec 08, 2004 at 16:22 UTC
I know that the code as written won't work, which is why I labeled it pseudocode. But thanks for clarifying. Yes, this is essentially the MockObject strategy. Thanks for adding the links.	[reply]