Testing & fixtures

The compiler’s correctness rests on a large fixture suite plus a TypeScript type-check gate. Both live under bynkc/tests/.

The fixture suite

tests/e2e.rs discovers every directory under tests/fixtures/positive/ and tests/fixtures/negative/ (currently 143 positive, 105 negative) and runs each as one fixture. There are two shapes:

Single-file

• input.bynk — the source (a self-contained commons).
• expected.ts — the exact emitted TypeScript (positive), or
• expected_error.txt — expected diagnostics (negative).

Project

• src/ — a source tree (one or more context/commons units).
• expected/ — the emitted output tree to match (positive), or expected_error.txt (negative).
• target.txt — optional; workers selects the Workers target (default bundle).
• bynk.toml — optional; enables split-paths mode.

runtime.ts and tsconfig.json are excluded from per-fixture comparison (they are checked separately).

How matching works

• Positive fixtures compare emitted files byte-for-byte against expected/ (or expected.ts).
• Negative fixtures match by substring: each non-blank, non-# line of expected_error.txt must appear somewhere in the concatenated "{code} {message}" of the diagnostics. So a line is usually just a code, e.g. bynk.refine.literal_violates.

The bless workflow

When you change the emitter (and the new output is correct), regenerate the positive fixtures’ expectations rather than editing them by hand:

BYNK_BLESS=1 cargo test -p bynkc bless_positive_fixtures

The bless_positive_fixtures test is a no-op unless BYNK_BLESS is set; with it set, it recompiles each positive fixture and overwrites expected/. Always review the resulting diff — blessing is how a regression silently becomes the new “expected” if you are not careful.

BYNK_BLESS is the project’s shared regenerate switch: the same run also refreshes the generated reference pages (see Working on the docs). Scope it to a specific test when you only mean to bless one thing.

The tsc verification gate

tests/tsc_verify.rs (emitted_typescript_passes_tsc_strict) compiles every project-form positive fixture and runs tsc --strict --noEmit over the output. It is a backstop for emitter bugs that produce TypeScript which round-trips our own comparison but does not actually type-check.

It needs tsc on PATH, or falls back to npx -p typescript@5 tsc. Behaviour when neither is available:

• locally — it logs a warning and passes (so a missing toolchain does not block you);
• in CI — set BYNK_REQUIRE_TSC=1 to make a missing tsc a hard failure.

Adding a feature: the definition of done

A grammar increment is not complete until:

1. positive and negative fixtures cover it (and pass);
2. emitted output type-checks under the tsc gate;
3. any new diagnostic code is added to the registry in diagnostics.rs;
4. the docs are updated in the same change — see Working on the docs.