To avoid the common mistake of re-arranging keypairs, provide them in a map which
forces the programmer to unpack the map in order to obtain the keys. This in turn makes
it harder to swap the PK/SK pair around and mistakenly giving out the secret key to the world.
Negative testing means we inject faulty data into the test now and then. When this happens, we make sure the SUT will
return some kind of badarg error for bad arguments. This means we should make sure things actually work out as they should.
As a side-effect, this can also be used to test for memory leaks. If run for a while, it makes sure there are no leaks in the code base,
and it probably also makes sure there are no ways to crash the server by any means of use of these NIFs. As such, it looks like the
NIFs are fairly stable.
