Tests fail when built with -DNDEBUG

[r-burns]

Since assert is a necessary part of the tests' control flow, compiling with NDEBUG defined globally (e.g. via config.cc.poptions+=-DNDEBUG) causes the tests to fail.

Forcibly undefining NDEBUG in each test driver before including <cassert> looks like one way to fix this:

--- a/tests/command/driver.cxx
+++ b/tests/command/driver.cxx
@@ -3,2 +3,5 @@
 
+#ifdef NDEBUG
+#undef NDEBUG
+#endif
 #include <cassert>

If this looks like an appropriate solution, I'm happy to open a PR.

[r-burns]

Cool, it looks like this was addressed in 7a4fc37. I was even able to cherry-pick it back to 0.13 (excluding any newly-added tests) and all tests are passing with global -DNDEBUG now. Thanks @karen-arutyunov!