This defines useful macros, in particular to print information and to
define tests and test suites.
The idea is a suite will be a set of test functions, where a test
function will fail <=> an assert is called. This allows us to stop
testing immediately upon a test failing and produce viable output.
Folder per module in test/. Header only tests with one actual main
file to implement a program that runs them.
Makefile runs the test and provides some eye candy to show if the test
succeeded or failed. The tests, on the other hand, will show success
or failure for each of them.
