# Conformance suite

pytest tests that assert an emulator correctly implements the control contract
(`../SPEC.md`, 0.1.x). Point them at any emulator — the reference x16emu, FAB,
the Neo6502 — and they check the same surface. Platform-agnostic: framebuffer
dimensions come from the PPM header, addresses use `$0000`, and `bank` is
exercised without requiring the platform to have banking.

## Run

Attach to an already-running emulator:

```
RRDC_PORT=8080 pytest -v
```

Or let the suite launch one (`{port}` is substituted into the command):

```
RRDC_EMU_CMD="SDL_VIDEODRIVER=dummy SDL_AUDIODRIVER=dummy \
    /path/to/x16emu -rom rom.bin -warp -controlport {port}" \
RRDC_PORT=8391 pytest -v
```

If nothing is listening and no `RRDC_EMU_CMD` is set, the tests **skip** (a bare
`pytest` in CI without an emulator is a skip, not a failure).

## What it checks

- `/status` — required keys present, contract MAJOR matches, sane types.
- `/regs` — a non-empty JSON object of integer registers.
- `/mem` — returns exactly `len` bytes; honours `bank`.
- `/screenshot` — a well-formed PPM whose body size matches its dimensions.
- `/step` — deterministic: equal steps advance the frame counter by equal,
  positive amounts, and `/step` returns the halted counter.
- `/pause` + `/resume` — toggle the paused state.
- Errors — unknown path → 404; `GET /step` → 405.

## Environment

| Var | Default | Meaning |
|---|---|---|
| `RRDC_PORT` | `8080` | control port to attach to / launch on |
| `RRDC_EMU_CMD` | — | shell command to launch an emulator (`{port}` substituted) |
| `RRDC_BOOT_TIMEOUT` | `20` | seconds to wait for `/status` |

Requires `pytest`. Nothing else — the client is stdlib-only (Pillow is optional
and unused here).