Re: [Boost-users] [Test] How to Access Private Data from a Test

Subject: Re: [Boost-users] [Test] How to Access Private Data from a Test
From: Jürgen Hunold (jhunold_at_[hidden])
Date: 2015-06-25 16:52:08

Hi Merrill,

Am Donnerstag, 25. Juni 2015, 14:37:30 schrieb Merrill Cornish:
> In the Bad-Old-Days when I had to roll my own, I would define my tests
> as methods of a special test class.  If those tests needed to access
> private data in the classes under test, I would declare special test
> class as a friend of the class under test--one extra statement and
> everything worked.

In my opinion, a test should never access private data. But there are times 
and legacy code where I had no other choice, too.

> How do I do that using Boost test (1.58.0) with the AUTO_TEST family of
> macros?
> 
> In the labyrinth of macro expansions, I found a struct name with the
> argument name from  BOOST_AUTO_TEST_CASE(), but a friend of that name
> doesn't work.

for BOOST_AUTO_TEST_CASE(foo_test)

use

friend struct ::foo_test;

Note the "::" for the global namespace though it might work without.

> The ideal case would be to declare the string name in
> BOOST_AUTO_TEST_SUITE() as a friend so one friend declaration does it
> all.  Alternately, having to declare a separate friend for each
> BOOST_AUTO_TEST_CASE() would be tedious (especially for large classes),
> but it would work.

For BOOST_AUTO_TEST_SUITE(test_suite) use
friend struct test_suite::foo_test;

Rule of thumb: Each SUITE(bar)  just add another namespace "bar" into the 
chain.

> At the moment, I'm using the ole private=public trick:
> 
>      #define private public
>      #include "header_under_test"
>      #undef private
>
> However, I've already discovered one system header, <sstream>, that
> won't work with that kludge.  There may be others.

Won't work with msvc because it mangles the access control specifiers into the 
symbol name. No luck then...
 
> Is there another workaround for Boost Tests?  I can't be the only one
> who has to access private data in tests.

Been there, done that. Just had to grep the examples out of one of my test 
suites...

Yours,

Jürgen
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