I don't really know why it was still in cmdgen.c at all. There's no
reason it shouldn't live in its own source file, and keep cmdgen.c for
the actual code of the key generation program!
cmdgen.c has contained code for ages to build a test main() if you
compile with -DTEST_CMDGEN. But it's painful to do so manually, since
you've still got to link in all the same supporting objects, and also
nobody can have actually done that for a while because the stub test
code hasn't been kept up to date with changes in the internal APIs
(specifically prompt_t).
Now we have the ability to include our test programs in Recipe as [UT]
or [XT] so as to leave them out of 'make install', that seems like a
useful thing to do with cmdgen's test suite. So here's a Recipe change
that builds it as 'cgtest', plus fixes for compiler warnings and bit
rot. Pleasantly, the test suite still _passes_ after those are fixed.
Simon Tatham