> There doesn't seem to be a simple, generic way to negate an arbitrary test in Test::More AFAICT.

I just realized that all tests return a boolean result.

So here a workaround:

use strict;
use warnings;
use Test::More;


sub fail_ok (&;@) {
    my ($code,$description) = @_;

    my $result;
  TODO:
    {
        local $TODO= "should be silent";
        my $result = $code->();
    }

    $result
      ? fail($description)
        : pass($description);
}

fail_ok { is(1,2,"") }
  "Bingo! Test failed";

done_testing;
[download]

The TODO block ensures that there is no failed test in the final result.

But I still need to understand how to make the output of the failed inner test silent ... °

... I probably need to redirect the STDERR output of Test::Builder or fiddle with TAP altogether

    
-*- mode: compilation; default-directory: "d:/exp/" -*-
Compilation started at Fri Jul 24 13:02:20

C:/Perl_524/bin\perl.exe -w d:/exp/pm_negate_test.pl 
not ok 1 -  # TODO should be silent
#   Failed (TODO) test ''
#   at d:/exp/pm_negate_test.pl line 21.
#          got: '1'
#     expected: '2'
ok 2 - Bingo! Test failed
1..2

Compilation finished at Fri Jul 24 13:02:21
[download]

°) Hmm... probably with subtests...

Are you testing regular code, or testing other tests?

If the former, why not just something like

my $cond = 1 == 2;
ok( $cond   ); # fails 
ok( ! $cond ); # passes
[download]

... or whatever boolean condition.

If the latter, Test::Builder::Tester seems designed to test other tests.

To be fair, I could be misunderstanding - this is not a use case I've come across before.

> If the former, why not just something like

I'm looking for a generic approach, is_deeply is an example where its not that easy, but reiterating an example with is_deeply would lead the thread again into a different direction.

So either I give a trivial example which is too easy or a complex where people are concentrating on the concrete example instead discussing the abstraction.

> If the latter, Test::Builder::Tester seems designed to test other tests.

Good call! looks promising, thanks. :)

> Are you testing regular code, or testing other tests?

Both. I already experimented with Test::Builder to generate another Test object redirecting the output.

Cheers Rolf
_{(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery}

> But I still need to understand how to make the output of the failed inner test silent ... °

FWIW, this will silence the output, tho using a new Test::Builder object or using Test::Builder::Tester might be the better approach.

use strict;
use warnings;
use Test::More;

my $Test = Test::Builder->new;

sub fail_ok (&;@) {
    my ($code,$description) = @_;

    #  --- silence output
    my $ignore;
    $Test->output(\$ignore);
    $Test->failure_output(\$ignore);
    $Test->todo_output(\$ignore);

    my $result;
  TODO:
    {
        local $TODO= "should be silent";
        #my $result = subtest "Negation of $description", $code;
        my $result = $code->();
    }

    # --- undo silence
    $Test->reset_outputs;

    #  --- output result
    $result
      ? fail($description)
        : pass($description);
}

fail_ok { is(1,2,"") }
  "Bingo! Test failed";


fail_ok { is(1,3,"") }
  "Bingo! Test failed again";

done_testing;
[download]

C:/Perl_524/bin\perl.exe -w d:/exp/pm_negate_test.pl 
ok 2 - Bingo! Test failed
ok 4 - Bingo! Test failed again
1..4
[download]

Cheers Rolf
_{(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery}