Is there a function in boost::test that can return error value?

Question

Boost Test Library is a very useful unit test framework. However, one thing I feel uncomfortable is that during the unit test if errors happen it will inform the user but not the program itself. Let me make my point clear by using BOOST_CHECK as an example:

i=3;
j=4;
BOOST_CHECK(i==j);

The above test case will fail. So, checking the details to find why this test fails will be very interesting. In this case, printing some variables or performing more complicated operations such as writing a file to the disk in the program will be necessary if it knows that the unit test fails. However, BOOST_CHECK will not return a value to denote the test is successful or not. A perfect function should work like this:

    i=3;
    j=4;
    if(Enhanced_BOOST_CHECK(i==j) == failed)
    {

        // print some internal varaibles.
        // or write some data to a file in the disk
     }

So my question is: does BOOST Test Library support this functionality? Thanks.

Answer 1

Boost provides a macro BOOST_WARN_MESSAGE (and BOOST_CHECK_MESSAGE and BOOST_REQUIRE_MESSAGE as well). In your case it could be used like this:

i=3;
j=4;

bool isEqual = i==j;

BOOST_CHECK(isEqual);
BOOST_WARN_MESSAGE(isEqual, "Failure since i = " << i << " and j = " << j);

Further info is found here .

Answer 2

Boost Test offers a lot more than just BOOST_CHECK .

See the docs :

The UTF testing tools reference

 BOOST_<level> BOOST_<level>_BITWISE_EQUAL BOOST_<level>_CLOSE BOOST_<level>_CLOSE_FRACTION BOOST_<level>_EQUAL BOOST_<level>_EQUAL_COLLECTION BOOST_<level>_EXCEPTION BOOST_<level>_GE BOOST_<level>_GT BOOST_<level>_LE BOOST_<level>_LT BOOST_<level>_MESSAGE BOOST_<level>_NE BOOST_<level>_NO_THROW BOOST_<level>_PREDICATE BOOST_<level>_SMALL BOOST_<level>_THROW BOOST_ERROR BOOST_FAIL BOOST_IS_DEFINED 

You may want to use BOOST_CHECK_EQUAL(i, j) in your case.

Alternatively, looking at your second example, for more complex cases, you simply can do:

if (!(i==j)) {
  // Complex condition failed - report to boost test and add custom message
  std::string message = ...;
  BOOST_CHECK_MESSAGE(false, message);
}