libretro/wiki/testing-guide.md

# Testing Guide

This page covers how to run, understand, and extend the test suite.

The suite is discovered dynamically across focused modules, so its exact count
is reported by the test runner instead of being hand-maintained here. Tests do
not require network access. Most build synthetic fixtures under the repository's
`tmp/`; modules that read real artifacts skip cleanly when those inputs are absent.

## Running tests

Run the full suite:

```bash
python -m unittest discover -s tests -t . -v
```

Run a single module, or several:

```bash
python -m unittest tests.test_e2e -v
python -m unittest tests.test_install tests.test_install_cores -v
```

The table below says which module covers what.

Running the build needs Python 3.12 and `pyyaml` alone, and so does most of the suite. The
schema contract tests also need `jsonschema[format-nongpl]`, which the CI
installs: without it they are reported as skipped, so install it before a pull
request that touches a profile, a platform file or a schema
(`pip install "jsonschema[format-nongpl]"`). No test framework beyond the
standard library `unittest` module.

## Modules at a glance

Every module in `tests/`, by the area it guards.

| Area | Fixtures | Modules |
|------|----------|---------|
| Core regression suites | synthetic | `test_e2e`, `test_audit_regressions` |
| File resolution and identity | synthetic + collection | `test_adler32_resolution`, `test_agnostic_scan`, `test_agnostic_scan_mode`, `test_agnostic_scope`, `test_agnostic_substitute`, `test_archive_choice`, `test_bios_companions`, `test_bundled_identity`, `test_casefold_cache`, `test_db_aliases`, `test_declared_names`, `test_derivations`, `test_directory_entries`, `test_extra_identity`, `test_foreign_tree`, `test_foreign_tree_names`, `test_frontend_digest`, `test_game_data_homonyms`, `test_hashing`, `test_identity`, `test_md5_pack_context`, `test_name_tiebreak`, `test_nec_filing`, `test_owner_resolution`, `test_path_suffix`, `test_resolution_evidence`, `test_shipped_content`, `test_twin_declarations`, `test_validated_choice`, `test_variant_choice`, `test_variant_identity`, `test_zipped_member` |
| Verification, cross-reference and profile checks | synthetic + profiles | `test_crypto_aes`, `test_crypto_unique_data`, `test_crypto_verify`, `test_case_insensitive_platforms`, `test_checks_have_values`, `test_core_file_fills_declaration`, `test_cross_reference_sources`, `test_file_consumers`, `test_fileless_audit`, `test_gap_settlement`, `test_hidden_extras`, `test_native_mode`, `test_no_case_collisions`, `test_path_conflict_status`, `test_path_null_copies`, `test_profile_checks`, `test_romm_hash_rule`, `test_shared_groups`, `test_standalone_mode`, `test_undeclared_dedup`, `test_unplaced_extras`, `test_validation_scope`, `test_verify_all_dir`, `test_verify_emulator_evidence`, `test_verify_listing`, `test_verify_pack_choice` |
| Packs and manifests | synthetic + real packs | `test_artifact_lock`, `test_atomic_artifacts`, `test_batocera_cores`, `test_deterministic_zip`, `test_emulator_pack_counts`, `test_finalize_pack_names`, `test_large_file_cache`, `test_libretro_layout`, `test_manifest_entry`, `test_pack_conformance_dirs`, `test_pack_counts`, `test_pack_failures`, `test_pack_file_names`, `test_pack_grouping`, `test_pack_integrity`, `test_pack_member_identity`, `test_pack_readme`, `test_platform_inheritance`, `test_platform_keys`, `test_required_only_archives`, `test_required_only_twins`, `test_split_extras`, `test_split_names`, `test_split_pack`, `test_system_pack_extras`, `test_system_pack_parity`, `test_torrentzip`, `test_which_pack` |
| Slots and regions | synthetic + profiles | `test_region`, `test_region_agnostic_scan`, `test_region_groups`, `test_region_held`, `test_region_platform_index`, `test_region_required_only`, `test_slot`, `test_slots`, `test_slots_shipped_file` |
| Hardware targets and systems | synthetic + target files | `test_extract_targets`, `test_lakka_targets`, `test_libretro_slugs`, `test_system_ids`, `test_system_selection`, `test_target_names`, `test_target_scrapers`, `test_target_systems`, `test_target_verify` |
| Installer and downloads | loopback server | `test_check_release`, `test_download`, `test_install`, `test_install_cores`, `test_install_experience`, `test_install_selection` |
| Truth and native export | synthetic + cached originals | `test_export_counts`, `test_export_native_layer`, `test_exporters`, `test_truth_diff`, `test_truth_layout` |
| Scrapers, upstream and provenance | inline sources, synthetic | `test_check_freshness`, `test_dedup`, `test_fbneo_parser`, `test_find_pinned_revision`, `test_hash_merge`, `test_mame_parser`, `test_mame_ref_audit`, `test_profile_sync`, `test_provenance`, `test_refresh_data_dirs`, `test_refresh_failures`, `test_refresh_stale`, `test_retrodeck_scraper_errors`, `test_romset_recipes`, `test_scraper_contract`, `test_upstream`, `test_upstream_index` |
| Site, docs and repository contracts | rendered pages, sources | `test_contributing_text`, `test_data_dir_refs`, `test_dataclass_defaults`, `test_optional_dependencies`, `test_site_availability`, `test_site_cores`, `test_site_exports`, `test_site_platform_hashes`, `test_site_system_links`, `test_site_validation`, `test_site_write`, `test_validate_pr`, `test_validate_pr_hashes`, `test_workflow_paths` |

## Test architecture

### test_e2e.py

The main regression suite. `TestE2E` exercises the resolution, verification,
pack generation and cross-reference logic; `StandaloneModeRequiresAStandaloneBuild`
sits beside it for the per-emulator build mode.

**Fixture pattern.** `setUp` creates a temporary directory tree with:

- Fake BIOS files (deterministic content for hash computation)
- Platform YAML configs (existence mode, MD5 mode, inheritance, shared groups)
- Emulator profile YAMLs (required/optional files, aliases, HLE, standalone)
- A synthetic `database.json` keyed by SHA1

`tearDown` removes the temporary tree.

**Test numbering.** Tests are grouped by category:

| Range | Category |
|-------|----------|
| `test_01`--`test_14` | File resolution (SHA1, MD5, name, alias, truncated MD5, composite, zip contents, variants, hash mismatch) |
| `test_20`--`test_31` | Verification (existence mode, MD5 mode, required/optional severity, zipped file, multi-hash) |
| `test_40`--`test_51` | Cross-reference and platform grouping (undeclared files, standalone skip, alias profiles, data dir suppression, exclusion notes) |
| `test_60`--`test_61` | Storage tiers (external, user-provided) |
| `test_70`--`test_84` | Emulator-level validation (index build, size, CRC32, MD5, SHA1, crypto) |
| `test_90`--`test_125` | Per-emulator and per-system verification, `dest_hint` resolution, registry metadata |
| `test_130`--`test_183` | Pack generation (required-only, split, `--from-md5`, path conflicts, archive extras, truth generation, exporters) |
| `test_200`--`test_227` | Pack source variants, deterministic ZIPs, SHA256/CRC32 resolution, MiSTer scraper, manifests |

Numbers are stable anchors, not an execution order. When a range fills up, a
letter suffix keeps a new test next to the behavior it covers
(`test_130b_existence_pack_reports_hash_mismatch`).

Each test calls the same functions that `verify.py` and `generate_pack.py` use
in production, against the synthetic fixtures.

### Parser tests

**test_mame_parser.** Tests the MAME C source parser that extracts BIOS root
sets from driver files. Fixtures are inline C source snippets containing
`ROM_START`, `ROM_LOAD`, `GAME()`/`COMP()` macros with
`MACHINE_IS_BIOS_ROOT`. Tests cover:

- Standard `GAME` macro detection
- `COMP` macro detection
- `ROM_LOAD` / `ROMX_LOAD` parsing (name, size, CRC32, SHA1)
- `ROM_SYSTEM_BIOS` variant extraction
- Multi-region ROM blocks
- Macro expansion and edge cases

**test_fbneo_parser.** Tests the FBNeo C source parser that identifies
`BDF_BOARDROM` sets. Same inline fixture approach.

**test_hash_merge.** Tests the text-based YAML patching module used to merge
upstream BIOS hashes into emulator profiles. Covers:

- Merge operations (add new hashes, update existing)
- Diff computation (detect what changed)
- Formatting preservation (comments, ordering, flow style)

Fixtures are programmatically generated YAML/JSON files written to a temp
directory.

### Provenance and installer tests

**test_provenance.** Covers the dump-catalog pipeline end to end on synthetic
DATs: the Logiqx XML parser, the Redump scraper's parsing path, the DAT pack
importer, the SHA1-then-MD5+size join performed by `generate_db.py`, and the
coverage report's covered/uncovered DAT accounting.

**test_install.** Covers `install.py` without touching the network: OS
detection, each registry detection method (`config_file`, `path_exists`,
`file_exists`), config-file key parsing, manifest loading, target filtering,
and destination resolution.

**test_profile_sync.** Covers ref anchoring end to end: the six statuses,
widening a one-line anchor until it is unique, refusing to rebase an ambiguous
one, following a rename, and the guarded YAML writes. Network access is
replaced by an injected fetch function.

**test_upstream.** Covers forge URL parsing for GitHub, GitLab and Forgejo,
the content-addressed cache and its atomic write, revision and tag resolution,
and tree comparison. The HTTP layer is replaced at module level, so nothing
leaves the machine.

### Tests that read the working tree

Three modules assert on real repository data instead of fixtures. Each skips
when its input is missing, so a partial checkout still runs green.

**test_torrentzip.** Rebuilds real MAME romsets through the TorrentZip builder
and asserts the output is byte-identical, which is what keeps arcade ZIP hashes
stable across rebuilds.

**test_no_case_collisions.** Walks `bios/` and fails on two paths that differ
only by case. On Windows and macOS, git can only check out one of them, which
silently corrupts the clone. `.variants/` is exempt: those names are
disambiguated by a hash suffix on purpose.

**test_pack_integrity.** Described below; needs packs in `dist/`.

## How to add a test

1. **Pick the right category.** Find the number range that matches the
   subsystem you are testing. If none fits, start a new range after the last
   existing one.

2. **Create synthetic fixtures.** Write the minimum YAML configs and fake
   files needed to isolate the behavior. Use `tempfile.mkdtemp` for a clean
   workspace. Avoid depending on the repo's real `bios/` or `platforms/`
   directories.

3. **Call production functions.** Import from `common`, `verify`, `validation`,
   or `truth` and call the same entry points that the CLI scripts use. Do not
   re-implement logic in tests.

4. **Assert specific outcomes.** Check `Status`, `Severity`, resolution
   method, file counts, or pack contents. Avoid brittle assertions on log
   output or formatting.

5. **Run the full suite.** After adding your test, run `python -m unittest
   discover tests -v` to verify nothing else broke.

Example skeleton:

```python
def test_42_my_new_behavior(self):
    # Write minimal fixtures to self.root
    profile = {"emulator": "test_core", "files": [...]}
    with open(os.path.join(self.emulators_dir, "test_core.yml"), "w") as f:
        yaml.dump(profile, f)

    # Call production code
    result = verify_platform(self.config, self.db, ...)

    # Assert specific outcomes
    self.assertEqual(result[0]["status"], Status.OK)
```

### test_pack_integrity.py

End-to-end pack verification. Extracts each platform ZIP to `tmp/` (in the
repo, not `/tmp` which is tmpfs on WSL) and verifies that every file declared
in the platform YAML:

1. Exists at the correct path on disk after extraction
2. Has the correct hash per the platform's native verification mode

Handles inner ZIP verification for MAME/FBNeo ROM sets (checkInsideZip,
md5_composite, inner ROM MD5) and path collision deduplication.

One test per distinct pack contract: RetroArch, Batocera, BizHawk, EmuDeck,
Recalbox, RetroBat, RetroDECK, RomM. Inherited aliases such as Lakka reuse the
same artifact and are not counted twice.

```bash
python -m unittest tests.test_pack_integrity -v
# or via CLI:
python scripts/generate_pack.py --all --verify-packs --output-dir dist/
```

Integrated as pipeline step 6/8 (runs after consistency check, before
README generation). Requires packs in `dist/`; skip with `--skip-packs`.

## Verification discipline

The test suite is one layer of verification. The full quality gate is:

1. All unit tests pass (`python -m unittest discover -s tests -t .`)
2. The full pipeline completes without error (`python scripts/pipeline.py --offline`)
3. No unexpected CRITICAL entries in the verify output
4. Pack file counts match verification file counts (consistency check)
5. Pack integrity passes (every declared file extractable with correct hash)
6. `mkdocs build --strict` and `python scripts/validate_site.py` pass

If a change passes tests but breaks the pipeline, it's worth investigating before merging. Similarly, new CRITICAL entries in the verify output after a change usually indicate something to look into. The pipeline is designed so that all steps agree: if verify reports N files for a platform, the pack should contain exactly N files.

Ideally, tests, code, and documentation ship together. When profiles and platform configs are involved, updating them in the same change helps keep everything in sync.

## CI integration

The `validate.yml` workflow runs `python -m unittest discover -s tests -t . -v` on both
roads into main: every pull request, and every direct push, that touches
`bios/`, `platforms/`, `emulators/`, `schemas/`, `scripts/`, `tests/` or
`install.py`. Work reaches main by push as often as by pull request, so a suite
wired to pull requests alone would guard the road nobody takes. The test job
(`run-tests`) runs in parallel with schema validation, and on a pull request
with BIOS validation and auto-labeling too; those two read pull request context
and stay behind an event guard.

A push series collapses to the tip, so what a green run states is that the head
of main passes, not every commit under it.

Modules that need real artifacts skip themselves when those artifacts are absent,
so `test_pack_integrity` is a no-op in CI (no `dist/`) and a real check locally.
Run `python -m unittest discover -s tests -t .` before pushing.

Tests must pass before merge. If a test fails in CI, reproduce locally with:

```bash
python -m unittest discover -s tests -t . -v
```