Re: [Boost-users] whitebox testing with boost unit test framework?

22 Dec 2011

      Thanks to all for the suggestions!  You are correct that I'm testing
"legacy" code, though in this particular case the legacy code is
completely open for change.  But, I need unit tests before I go
mucking about so I know that I haven't made things any worse than they
are.

On Wed, Dec 21, 2011 at 7:04 PM, Ahmed Badran  wrote:
...
That is what I've come to accept as probably the cleanest possible solution
without hacking/redefining "private"/"protected" in production vs. test code
(even though it's far from what I would call elegant).
For a class I essentially create a friend in a completely different "test"
namespace, the unit tests go in that namespace and are linked against the
object files to test them and validate class internals/invariants. The
shipping code (headers) always have the 'missing' friend declarations, but
as I said it's a 1 line that I've gotten to accept as the least ugly
solution until I come across something that's more elegant.
For some reason I'm having difficulties implementing this suggestion.

The "legacy" code lives in a namespace, e.g.,

// ClassToBeTested.hh
namespace mycompany {
namespace internal {
class ClassToBeTested { ... };
} // namespace internal
} // namespace mycompany

If I understand the suggestion, I think I want to put the testing in a
different namespace, e.g.,

// test_ClassToBeTested.cxx
namespace mycompany {
namespace internal {
namespace test {
  // here lies the boost unit test stuff that I create
  struct ClassToBeTested_suite_fixture { ... };
  BOOST_FIXTURE_TEST_SUITE( ClassToBeTested_suite,
ClassToBeTested_suite_fixture )
  ... here lie unit tests...
  BOOST_AUTO_TEST_SUITE_END()
} } }

So, in the declaration for ClassToBeTested, I should have something like

class ClassToBeTested {
public:
  // public interface
protected:
  // protected members/methods
  friend class mycompany::internal::test::ClassToBeTested_suite_fixture;
};

When I compile, the compiler complains that it does not know about
namespace 'test'

]$ clang++ namespace_test.cxx
namespace_test.cxx:4:46: error: no member named 'test' in namespace
'mycompany::internal'
         friend class
::mycompany::internal::test::ClassToBeTested_suite_fixture;
                      ~~~~~~~~~~~~~~~~~~~~~~~^
namespace_test.cxx:6:8: error: expected external declaration
   } } }
       ^
2 errors generated.

The only way I've found around this is to forward declare
ClassToBeTested_suite_fixture in the ClassToBeTested header, e.g.,

// ClassToBeTested.hh
namespace mycompany {
namespace internal {
namespace test { class ClassToBeTested_suite_fixture; }
class ClassToBeTested { ... };
} // namespace internal
} // namespace mycompany

Is this the technique that you use?  I wonder, because it's more than
one lane and still intrusive, and I'm wondering if I'm missing
something.

-- 
Chris Cleeland