I've had this hanging around for ages, but I'm not happy with it yet. I should really generalise it into some sort of Test::Filehandle. However it may be of use as a starting point:

#! /usr/bin/perl -w

package Test::Output;
use 5.005;
use strict;
use Sub::Uplevel;
use Test::Builder;
use IO::File;
use Fcntl;
use Symbol qw(qualify_to_ref gensym);
use base qw(Exporter);


use vars qw($VERSION @EXPORT);
$VERSION = '0.01';
@EXPORT = qw(output_is output_isnt output_like output_unlike);


sub _try_as_caller {
    my ($sub, $level) = @_;
    eval { uplevel $level, $sub };
    return $@;
};


my $Last_output;

sub _get_output {
    my ($code, $fh, $level) = @_;
    $fh = qualify_to_ref($fh, caller);
    my $tmp = IO::File->new_tmpfile or die "no tmp file ($!)";
    my $old = gensym;
    *$old = *$fh;
    local *$fh = $tmp;
    my $exception = _try_as_caller($code, $level);
    *$fh = *$old;
    die if $exception;
    seek $tmp, SEEK_SET, 0 or die "could not seek ($!)";
    my $output = '';
    my $n;
    while ($n = read $tmp, $output, 1024, length($output)) {};
    die "could not read ($!)" unless defined($n);
    return($Last_output = $output);
};


sub _test_output {
    my ($method, $code, $expected, $fh, $name) = @_;
    my $builder = Test::Builder->new;
    my $todo = $builder->exported_to;
    local $Test::Builder::Level = 2;
    $builder->$method(_get_output($code, $fh, 6), $expected, $name);
};


sub output_is       (&$*;$) { _test_output('is_eq',  @_) };
sub output_isnt     (&$*;$) { _test_output('isnt_eq',@_) };
sub output_like     (&$*;$) { _test_output('like',   @_) };
sub output_unlike   (&$*;$) { _test_output('unlike', @_) };


sub last { $Last_output };

1;

[download]

Use something like:

  output_is     { hello() } "hello world\n", STDOUT, "hello world";
  output_isnt   { hello() } "goodbye",       STDOUT, "not goodbye";
  output_unlike { hello() } qr/bye/,         STDOUT, "didn't print bye
+";
  output_like   { hello() } qr/hello/,       STDOUT, "printed hello";
  like(Test::Output->last, qr/world/, "... and world");

[download]

(yes, I know,  _get_output sucks ;-)

In reply to Re: Tests for 'printing' code by adrianh
in thread Tests for 'printing' code by dda

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