erlang: extract ffi test suite (637/637, ffi 14/14)

plans/erlang-on-sx.md

@@ -120,12 +120,14 @@ Replace today's hardcoded BIF dispatch (`er-apply-bif`/`er-apply-remote-bif` in
 - [x] `file:read_file/1`, `file:write_file/2`, `file:delete/1` — **+10 eval tests** (633/633 total). Returns `{ok, Binary}` / `ok` / `{error, Reason}` where Reason is `enoent`/`eacces`/`enotdir`/`eisdir`/`posix_error` (classified from the SX `file-read`/`-write`/`-delete` exception string). Path accepts SX string, Erlang binary, or Erlang char-code list. `file:list_dir/1` deferred — no directory-listing primitive in this SX runtime; see Blockers.
 - [ ] `httpc:request/4` — **BLOCKED** (no HTTP client primitive). See Blockers.
 - [ ] `sqlite:open/1`, `sqlite:close/1`, `sqlite:exec/2`, `sqlite:query/2` — **BLOCKED** (no SQLite primitive). See Blockers.
-- [ ] Tests: 1 round-trip per BIF; suite name `ffi`; conformance scoreboard auto-picks it up. Target +40 ffi tests, ~570/570 total
+- [x] Tests: 1 round-trip per BIF; suite name `ffi`; conformance scoreboard auto-picks it up — **+14 ffi tests** at 637/637 total. Suite covers the 3 implemented file BIFs (9 tests: write-ok, read-ok-tag, payload-is-binary, byte_size content, missing-enoent, bad-path-enoent, binary-payload round-trip, delete-ok, read-after-delete-enoent) plus 5 negative asserts (one per blocked BIF — `crypto:hash`/`cid:from_bytes`/`file:list_dir`/`httpc:request`/`sqlite:exec`) so this suite fails fast if a future iteration adds a wrapper without registering proper tests. Target "+40 ffi tests" was relative to the original 5-BIF-family plan; with 5 of those families blocked on host primitives, the achievable count is 14 — the suite scaffolding is what matters and is ready to accept the remaining tests when the primitives land.
 
 ## Progress log
 
 _Newest first._
 
+- **2026-05-14 ffi test suite extracted, conformance scoreboard auto-picks it up** — New `lib/erlang/tests/ffi.sx` with its own counter trio (`er-ffi-test-count`/`-pass`/`-fails`) and `er-ffi-test` helper following the same pattern as runtime/eval/ring tests. The 10 file BIF eval tests from the previous iteration moved out of `eval.sx` (eval dropped from 395 to 385 tests) and into the new suite where they're now 9 tests (consolidated the two write+read tests). `conformance.sh` updated: added `ffi` to `SUITES` array with `er-ffi-test-pass`/`-count` symbols, added `(load "lib/erlang/tests/ffi.sx")` after `fib_server.sx`, added `(epoch 109) (eval "(list er-ffi-test-pass er-ffi-test-count)")`. Scoreboard markdown auto-updated to include the row. Suite also asserts that the 5 blocked BIFs (`crypto:hash`, `cid:from_bytes`, `file:list_dir`, `httpc:request`, `sqlite:exec`) are NOT yet registered — turns a future "added the wrapper but forgot to extend ffi tests" into a hard failure. One eval-comparison gotcha en route: SX's `=` does identity equality on dicts so comparing two separately-constructed `(er-mk-atom "true")` values is false; the existing eval suite has an `eev-deep=` helper that handles this, but the simpler fix in ffi was to extract `:name` via `ffi-nm` and compare strings. Total **637/637** (+14 ffi). Phase 8 fully ticked aside from the BLOCKED bullets — those remain unchecked with explicit Blockers references.
+
 - **2026-05-14 file BIFs landed; crypto/cid/list_dir/http/sqlite blocked on missing host primitives** — Three new FFI BIFs registered in `runtime.sx`: `file:read_file/1`, `file:write_file/2`, `file:delete/1`. Each wraps the SX-host primitive (`file-read`, `file-write`, `file-delete`) inside a `guard` that converts thrown exception strings into Erlang `{error, Reason}` tuples. New helper `er-classify-file-error` does loose pattern-matching on the error message using `string-contains?` to map to standard POSIX-style reasons: `"No such"` → `enoent`, `"Permission denied"` → `eacces`, `"Not a directory"` → `enotdir`, `"Is a directory"` → `eisdir`, fallback `posix_error`. Filenames coerce through `er-source-to-string` so SX strings, Erlang binaries, and Erlang char-code lists all work. Read returns `{ok, Binary}` (bytes via `(map char->integer (string->list ...))` then `er-mk-binary`); write returns bare `ok`; delete returns bare `ok`. Bootstrap registrations added at the bottom of `er-register-builtin-bifs!` under `"file"`. 10 new eval tests: write-then-read round-trip, ok-tag, payload is binary, byte_size content, missing-file `enoent`, delete-ok, read-after-delete `enoent`, write to non-existent dir `enoent`, binary payload (5 raw bytes) round-trip preserving byte count. Blockers entry added covering five Phase 8 BIFs whose host primitives don't exist in this SX runtime: `crypto:hash/2`, `cid:from_bytes/1`/`to_string/1`, `file:list_dir/1`, `httpc:request/4`, `sqlite:open/exec/query/close`. Fix path documented inline (architecture-branch iteration to register OCaml-side primitives). Total **633/633** (+10 eval).
 
 - **2026-05-14 term-marshalling helpers landed** — `er-to-sx` (Erlang term → SX-native) and `er-of-sx` (SX-native → Erlang term) plus internal helper `er-cons-to-sx-list` (recursive cons-chain walker). All three live in `runtime.sx` next to the BIF registry. Conversion table: atom ↔ symbol via `make-symbol`/`er-mk-atom`; nil ↔ `()`; cons-chain → SX list (recursive marshal of each head); tuple → SX list (one-way — tuples flatten and can't be reconstructed without a tag); binary ↔ SX string (bytes ↔ char codes via `char->integer`/`integer->char`); integer / float / boolean passthrough; opaque types (pid, ref, fun) passthrough. SX strings on the way back become Erlang binaries — the natural FFI return shape. Empty SX list (`type-of` `"nil"`) marshals back to `er-mk-nil`. Edit gotchas during implementation: SX has no `while`, `string-ref`, or `string-length` primitive — used `(map char->integer (string->list s))` for byte extraction and a recursive helper for cons-walking. 23 new runtime tests in `tests/runtime.sx`: 10 covering `er-to-sx` (atom/atom-is-symbol, nil, int / float / bool passthrough, binary→string, cons→list, tuple→list, nested), 8 covering `er-of-sx` (symbol→atom, atom-tag, string→binary, byte content, int passthrough, empty-list→nil, list→cons length, head field), 4 round-trips (int, atom, binary bytes, list length), 1 negative documenting that tuple round-trip flattens to cons. Total **623/623** (+23 runtime).