when running `zig build functionaltest`, it might
take a while until the test harness nvim instance checks
for interrupts, which causes a lot of tests to keep running after
CTRL+C. Check after each test instead
This is in preparation of zig 0.17 where b.install_path is no
longer known inside `pub fn build()`.
Builds which should hardcode a runtime path into the binary has to specify it.
We could use a nlua0 helper to encode the install path at build time but
I think this is cleaner anyway. (like currently the appimage still
encodes a temporary build path which is nonsensical, it is better to
just include none)
Similarily b.args will not be available anymore (there will just
be an opaque pass-through)
Replace the busted-based Lua test runner with a repo-local harness.
The new harness runs spec files directly under `nvim -ll`, ships its own
reporter and lightweight `luassert` shim, and keeps the helper/preload
flow used by the functional and unit test suites.
Keep the file boundary model shallow and busted-like by restoring `_G`,
`package.loaded`, `package.preload`, `arg`, and the process environment
between files, without carrying extra reset APIs or custom assertion
machinery.
Update the build and test entrypoints to use the new runner, add
black-box coverage for the harness itself, and drop the bundled
busted/luacheck dependency path.
AI-assisted: Codex