Switch to using lc3tools-sys for the lc3tools test infrastructure

[rrbutani]

what

Right now when we test things against LC3Tools we run it via the shell and then parse it's command line output.

This mostly works and the command line output format, though not documented, is unlikely to change. But this approach has downsides:

• It doesn't work on Windows
• It requires that LC3Tools is already installed and that the LC3TOOLS_BIN env var is set

lc3tools-sys sidesteps these issues by packaging LC3Tools as a static library that's passed to cargo at build time and by offering some bindings for the LC3Tools API that we can call from Rust.

Additionally, using lc3tools-sys gives us a little more control over things like providing inputs and receiving outputs from the simulator and hooks to do things/be notified on ACVs. Right now lc3tools-sys only offers some bare minimum functionality but as we expand our test suite to be more comprehensive this will become a factor worth considering.

To start with though, we can just make it so the function in src/lc3tools/runner.rs uses lc3tools-sys instead of the shell (other functionality and hooks for the tests can come later, in other PRs).

steps

• identify the functionality that the current runner needs
• contrast this with what lc3tools-sys offers
  • for anything that's missing, add bindings and send in PRs to lc3tools-sys
• make the changes to the runner!

where

branch: imp-lc3tools-sys-tests

open questions

None right now.