WPT test harness and initial DOM pass rate #113

Set up the Web Platform Tests (WPT) harness and measure initial pass rate on DOM and event tests.

Scope#

WPT Submodule#

• WPT is already configured as a git submodule at tests/wpt/
• Contains thousands of browser conformance tests organized by specification
• Tests use testharness.js (a JS test framework) or are ref tests (visual comparison)

Test Harness (testharness.js support)#

• Implement enough of the WPT testharness.js API to run tests:
  • test(func, name) — synchronous test
  • async_test(name) — returns test object for async testing
  • t.step(func) — run a test step
  • t.done() — mark async test complete
  • promise_test(func, name) — Promise-based async test
  • assert_equals(actual, expected, description)
  • assert_not_equals(actual, expected, description)
  • assert_true(value, description) / assert_false(value, description)
  • assert_throws_js(constructor, func, description)
  • assert_throws_dom(name, func, description)

Test Runner#

• cargo test -p we-browser --test wpt integration test
• Discovers .html test files under tests/wpt/
• For each test:
  • Parse the HTML
  • Execute inline <script> elements
  • Collect pass/fail results from testharness.js assertions
  • Handle timeouts for hanging tests
• Report pass/fail/skip/error counts grouped by test directory

Test Scope (Initial)#

Focus on tests that exercise our Phase 11 implementations:

• dom/nodes/ — basic DOM manipulation tests
• dom/events/ — event dispatch and propagation tests
• dom/collections/ — NodeList and HTMLCollection tests
• html/dom/ — HTML DOM interface tests
• console/ — Console API tests (if any)

Skip for now:

• Visual/ref tests (require rendering comparison)
• Tests requiring features we haven't implemented (CSS OM, Web Workers, etc.)
• Tests requiring network access during test execution

Pass Rate Tracking#

• Print summary statistics: X/Y tests passing (Z% pass rate)
• Group results by test directory for visibility
• Track known-failing tests separately from errors/panics
• The test should pass cargo test even with failing WPT tests (report, don't assert)

Acceptance Criteria#

• WPT test runner discovers and executes HTML test files
• testharness.js assertions (assert_equals, assert_true, etc.) work
• Synchronous and async tests are supported
• Test results grouped by directory with pass/fail/skip counts
• Tests that panic don't crash the runner
• Timeout handling for hanging tests
• Integration with cargo test -p we-browser --test wpt
• Initial pass rate measured and reported for dom/ tests

Phase 11 — DOM-JS Bindings (issue 8 of 8). Depends on: all previous Phase 11 issues.