Test::MockObject and mocking module subroutines

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

I've just decided to try Test::MockObject for my tests but I have problems with it. The error message seems to indicate that the subroutine encoding_from_html_document is not exported by HTML::Encoding - but in the BEGIN block I try to mock this subroutine (perhaps the double "" is indication of some internal bug, but I am a novice here). Here is my code:

use Test::More tests => 1;

BEGIN {
    use Test::MockObject;
    Test::MockObject->fake_module ( 'HTML::Encoding',
        encoding_from_html_document => sub{ 'iso' }
    );
}

use_ok( Catalyst::Test, 'LinkDB' );
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And here is the error message when I try to run it:

1..1
not ok 1 - use Catalyst::Test;
#     Failed test (t/m/cdbi_link1.t at line 11)
#     Tried to use 'Catalyst::Test'.
#     Error:  Couldn't load "LinkDB", "Couldn't load "LinkDB::C::Bookm
+ark", ""encoding_from_html_document" is not exported by the HTML::Enc
+oding module
# Can't continue after import errors at lib/LinkDB/C/Bookmark.pm line 
+9
# BEGIN failed--compilation aborted at t/m/cdbi_link1.t line 11.
# Compilation failed in require at /usr/local/share/perl/5.8.4/Module/
+Pluggable/Fast.pm line 66.
# " at /usr/local/share/perl/5.8.4/Module/Pluggable/Fast.pm line 68.
# Compilation failed in require at /usr/local/share/perl/5.8.4/Catalys
+t/Test.pm line 78.
# " at /usr/local/share/perl/5.8.4/Catalyst/Test.pm line 80.
# BEGIN failed--compilation aborted at (eval 5) line 2.
# Looks like you failed 1 test of 1.
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What is wrong here?

I need to add that without the BEGIN block the test runs OK.

This is Test::MockObject VERSION = '0.20' and Perl version 5.8.4.

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Re: Test::MockObject and mocking module subroutines by chromatic (Archbishop) on Jun 22, 2005 at 16:26 UTC
`fake_module()` prevents Perl from loading HTML::Encoding, so if its `import()` does anything that the code your testing needs, you have to do it yourself. One option is to localize `*HTML::Encoding::encoding_from_html_document` or the glob in the appropriate package and assign your own subroutine to it there. I don't remember at the moment what Test::MockModule does, but it might handle this for you better than T::MO does.	[reply] [d/l] [select]

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Re: Test::MockObject and mocking module subroutines
by chromatic (Archbishop) on Jun 22, 2005 at 16:26 UTC

fake_module() prevents Perl from loading HTML::Encoding, so if its import() does anything that the code your testing needs, you have to do it yourself.

One option is to localize *HTML::Encoding::encoding_from_html_document or the glob in the appropriate package and assign your own subroutine to it there. I don't remember at the moment what Test::MockModule does, but it might handle this for you better than T::MO does.

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