I have a couple of annoying issues with Boost.Test's output on failed tests: 1) The printing code doesn't restore the iostream's original precision after it's changed it for formatted output. It's a minor issue but very annoying at times :-) Looks trivial to patch in print_log_value as well? 2) If the type has no numeric_limits support, say if it's a composite type, like std::complex<double> then you don't get enough digits to tell what the problem is. Could the code default to whatever digits long-double has? Again a minor change to print_log_value (in my experience std lib's ignore requests for more digits than a type really has anyway, so it should be harmless?). 3) If a BOOST_CHECK_CLOSE fails, you get the two values, but not what the % difference between them was. And it's the % difference that matters :-) I know this has come up before, but it's still bugging me. Here's the problem: if the type is say a 128-bit long double then you get two very long 35-digit numbers printed out: which have two many digits for the average calculator, so you can't even calculate the % difference manually to see how far off you were! Many thanks, John.