[boost] Test Tool Proposal (test_tools.hpp)

From: r.lichtenberger_at_[hidden]
Date: 2003-02-03 02:09:34

I suggest adding the following (or a similar) macro to test_tools.hpp:

#define BOOST_CHECK_EQUAL_MESSAGE(left_, right_, message_) \
    boost::test_toolbox::detail::equal_and_continue_impl((left_), 
(right_), \
        boost::test_toolbox::detail::wrapstrstream() << #left_ " == " 
#right_ << " (" << message_ << ")" , __FILE__, __LINE__)

Sometimes in a unit test one has got a function/method to check certain 
properties of an object in order to avoid duplicating lots of code

--- SNIP Example ---
MyObject* my1 = new MyObject(1, 2, 3);
BOOST_CHECK_EQUAL(my1->getA(), 1);
BOOST_CHECK_EQUAL(my1->getB(), 2);
BOOST_CHECK_EQUAL(my1->getC(), 3);

MyObject* my2 = new MyObject(4, 5, 6);
BOOST_CHECK_EQUAL(my2->getA(), 4);
BOOST_CHECK_EQUAL(my2->getB(), 5);
BOOST_CHECK_EQUAL(my2->getC(), 6);
--- SNIP ---

can be refactored into:

--- SNIP Example refactored ---
void checkMyObject(MyObject* my, int a, int b, int c) 
{
        BOOST_CHECK_EQUAL(my->getA(), a);
        BOOST_CHECK_EQUAL(my->getB(), b);
        BOOST_CHECK_EQUAL(my->getC(), c);
}

MyObject* my1 = new MyObject(1, 2, 3);
checkMyObject(my1, 1, 2, 3);
MyObject* my2 = new MyObject(4, 5, 6);
checkMyObject(my2, 4, 5, 6);
--- SNIP ---

The problem with the second version is that if the check for equality 
fails, the only output is the line number within checkMyObject() that 
failed. No hint about the calling line is present. Ideally all macros 
should print out a stack trace (as done in e.g. Java), but from my limited 
knowledge of C++ I guess that this is not (easily) possible, so 
introducing a BOOST_CHECK_EQUAL_MESSAGE macro is the second best solution 
IMHO:

--- SNIP Example with new macro ---
void checkMyObject(MyObject* my, int context, int a, int b, int c) 
{
        BOOST_CHECK_EQUAL_MESSAGE(my->getA(), a, context);
        BOOST_CHECK_EQUAL_MESSAGE(my->getB(), b, context);
        BOOST_CHECK_EQUAL_MESSAGE(my->getC(), c, context);
}

MyObject* my1 = new MyObject(1, 2, 3);
checkMyObject(my1, __LINE__, 1, 2, 3);
MyObject* my2 = new MyObject(4, 5, 6);
checkMyObject(my2, __LINE__, 4, 5, 6);
--- SNIP ---

Note that instead of using an int context we could also have a std::string 
or any other streamable object. Using an int and the __LINE__ macro is 
just convenient here.

Best regards, 
        Robert