On 4/5/2011 2:25 PM, Sebastian Nowozin wrote:
Hello Grennadiy,
On Tue, Mar 29, 2011 at 6:19 PM, Gennadiy Rozental<rogeeff@gmail.com> wrote:
BOOST_CHECK_DOUBLES_EQUAL(first, second, absolute_tolerance);
Use BOOST_CHECK_SMALL.
This does not do the job, as BOOST_CHECK_SMALL(std::fabs(first - second), 1.0e-3) will be about as useful as BOOST_CHECK(std::fabs(first - second)<= 1.0e-3)
It is not useful because in case this check fails I do not get to see the original values of both 'first' and 'second', but only their difference.
In my application, first and second are in the range of 0 to 1, but can in fact be quite close to zero. The qualitative test is correct if the absolute difference between first and second is small enough, irrespectively of the absolute value of first. Therefore, I fail to see why the boost test library provides only BOOST_CHECK_CLOSE and BOOST_CHECK_SMALL, but no analog to CPPUNIT_ASSERT_DOUBLES_EQUAL.
You can implement any check with a minor amount of code. Here, for example, is the test I have for making sure a quantity is within some tolerance of equality: template < typename Quantity > boost::test_tools::predicate_result compare_quantity(Quantity a, Quantity b, double tolerance) { double diff = abs(a.value() - b.value()); if ( diff > tolerance) { boost::test_tools::predicate_result res( false ); res.message() << "Quantities [" << a << "] and [" << b << "] do not fall within [" << tolerance << "]. Difference is [" << diff << "]"; return res; } return true; }