Test command line tools --- proposal

[elshize]

Proposal

This is one idea I had that doesn't involve some crazy complicated stuff in C++.

Basically, we have a hidden flag --print-arguments that doesn't show up in the help. We always have this pattern:

int main(int argc, char** argv)
{
    if (argc > 1 and argv[1]) {
        print_out(args(argc, argv));
    } else {
        std::apply(do_work, args(argc, argv));
    }
}

where print_out simply prints out the arguments so we can verify them in testing; and do_work is the entry function of the program, args is a program-specific function where you do all the CLI stuff and return a tuple to apply to the do_work function (names are just examples).

So now we can verify that we pass the right values by running a simple python script and compare the output.

Ideally, do_work should have its own integration test but that might be tricky sometimes. First, it must be separated in a header. In that case, some things would be compiled twice, which is an awful idea for things like queries.

There is one solution that might be a bit annoying. We'd have three files:

1. program.hpp
2. program.cpp
3. program_entry.cpp

The last one would be something like this:

#include program.hpp

int main(int argc, char** argv) {
    std::apply(do_work, args(argc, argv));
}

This is not ideal, but actually this would allow to directly test args from Catch.

Any thoughts? Other ideas?