75bc30bb8e
Implement parsing, evaluation, lexical this capture, and new rejection for arrow functions. Covers expression bodies, block bodies, zero/single/ multi-param forms, and backtracking disambiguation from grouping parens. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
124 lines
3.9 KiB
Markdown
124 lines
3.9 KiB
Markdown
# JavaScript Conformance Report
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Summary of the JS262 conformance test suite results. Tests are modeled after Test262
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but use our own harness since the interpreter doesn't yet support all features
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required by the Test262 harness (prototype chain remains).
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## Overall Results
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| Status | Count |
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|--------|-------|
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| Pass | 124 |
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| Known Fail | 4 |
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| Skip | 1 |
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| **Total** | **129** |
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## Results by Feature Area
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| Feature | Pass | Known Fail | Total |
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|---------|------|------------|-------|
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| expressions | 16 | 0 | 16 |
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| variable-declarations | 11 | 0 | 11 |
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| functions | 10 | 0 | 10 |
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| scheduling | 7 | 0 | 7 |
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| arrays | 6 | 0 | 6 |
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| control-flow | 6 | 0 | 6 |
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| dom-bindings | 6 | 0 | 6 |
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| errors | 6 | 0 | 6 |
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| events | 6 | 0 | 6 |
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| for-loops | 6 | 0 | 6 |
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| this-keyword | 5 | 0 | 5 |
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| promises | 5 | 0 | 5 |
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| try-catch | 5 | 0 | 5 |
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| types | 5 | 0 | 5 |
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| objects | 4 | 0 | 4 |
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| while-loops | 3 | 0 | 3 |
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| string-methods | 3 | 0 | 3 |
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| do-while-loops | 2 | 0 | 2 |
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| logical-ops | 2 | 0 | 2 |
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| compound-assignment | 1 | 0 | 1 |
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| computed-member | 1 | 0 | 1 |
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| function-call | 1 | 0 | 1 |
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| increment-decrement | 1 | 0 | 1 |
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| object-prototype | 1 | 0 | 1 |
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| switch | 1 | 0 | 1 |
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| template-literals | 1 | 0 | 1 |
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| arrow-functions | 3 | 0 | 3 |
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| bitwise-ops | 0 | 1 | 1 |
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| for-in | 0 | 1 | 1 |
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| instanceof | 0 | 1 | 1 |
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| ternary | 0 | 1 | 1 |
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## Known Failure Reasons
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| Feature | Reason |
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|---------|--------|
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| for-in | For-in loop not yet supported |
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| ternary | Ternary operator not yet supported |
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| arrow-functions | *(implemented — promoted to pass)* |
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| bitwise-ops | Bitwise operators not yet supported |
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| instanceof | instanceof operator not yet supported |
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| stack-overflow | Skipped — default recursion depth exhausts Rust stack before statement limit fires |
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## Harness Design
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The JS262 harness (`tests/js262_harness.rs`) supports two execution modes:
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- **script**: Runs JS through `JsEngine` with a `CaptureSink` for console output
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- **dom**: Runs JS through `WebApiFacade` with virtual clock for deterministic scheduling
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Tests can specify:
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- `expected_output`: Compare console output against a golden `.txt` file
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- `expected_error`: Verify error class (`parse`, `reference`, `type`, `runtime`)
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- `steps`: For dom-mode, specify clock advances and tick counts
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Policy enforcement uses the same 3-state matrix as the WPT harness:
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- Pass test that passes: OK
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- Pass test that fails: ERROR
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- Known-fail test that fails: OK (expected)
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- Known-fail test that passes: ERROR (promote it)
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## Real Test262 Tests (Phase A)
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50 real tests vendored from `tc39/test262` into `tests/external/js262/test262/`.
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Each test runs with `mode = "test262"`, which prepends `sta.js` and `assert.js` before execution.
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| Status | Count |
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|--------|-------|
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| Pass | 35 |
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| Known Fail | 15 |
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| **Total** | **50** |
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**Pass rate: 70%**
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### Results by Feature Area
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| Feature | Pass | Known Fail | Total |
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|---------|------|------------|-------|
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| asi | 3 | 2 | 5 |
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| block-scope | 12 | 8 | 20 |
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| comments | 5 | 0 | 5 |
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| directive-prologue | 5 | 0 | 5 |
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| expressions | 10 | 5 | 15 |
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### Known-Fail Categories
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| Category | Count | Details |
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|----------|-------|---------|
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| Strict mode | 5 | `"use strict"` directive enforcement not yet implemented |
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| ASI gaps | 2 | Automatic semicolon insertion edge cases |
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| Label syntax | 2 | Labeled statement parsing not supported |
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| Function decls in blocks | 2 | Block-scoped function declarations (Annex B) |
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| Other parser gaps | 4 | Various syntax not yet handled |
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## Test262 Migration Path
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Phase A is now complete. Next steps (Phase B):
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1. Vendor ~500 tests covering variables, expressions, functions, control flow
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2. Use Test262's `features` metadata to filter to supported features only
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3. Script the manifest generation: parse Test262 YAML frontmatter to TOML entries
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4. Track pass rate as a project metric
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See `docs/test262_roadmap.md` for the full gap analysis, tiered implementation plan,
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and integration strategy.
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