fix: use axe run options from accessibility-insights-web (disables empty-table-header rule)

[dbjorge]

Details

Today, Service decides which axe-core rules to use via a RuleExclusion mechanism that starts from axe-core's default ruleset an disables rules we don't use in web.

This is inconsistent with how accessibility-insights-web defines its ruleset (via a combination of axe-core's rule tags and explicit overrides). The difference in mechanisms led to a mistake during the axe-core 4.6.3 update where the rulesets became inconsistent between web and service.

To ensure consistency between web and service, this PR replaces rule-exclusion.ts with a new mechanism based on the recently-added @accessibility-insights/axe-config package in the web repo. That package builds an axe config blob based on web's get-rule-inclusions.ts mechanism. This update bundles a copy of the current output of that package into axe-configuration.ts to form the basis of service's axe configuration, and removes rule-exclusion.ts entirely as obsolete.

Besides keeping the rules in sync, this also means adds a new axe-core config option that was previously overridden by web but not service ("pingWaitTime": 1000 instead of the default 500ms). I decided to keep the new value from the web config for consistency with web and because both values are still very comfortably within the margin of error set by the page level timeouts used in page-timeout-config.ts, even assuming pages with multiple levels of iframe nesting.

Motivation

• Make it more reliable to keep web and service rules in sync.
• Disables the unintentionally-enabled empty-table-header best-practice rule

Context

• Builds on @sfoslund 's work in chore: add axe-config-generator package accessibility-insights-web#6395
• Partially implements (but doesn't complete) [Feature Request] Axe-core rules should be consistent between service and web #571
  • I considered doing a fuller implementation that would involve creating a publishing pipeline for the axe-config package, but I didn't want to tie up the fix for the rule inconsistency in service vs web with that process. This is still an incremental improvement that moves us closer to that end state without the NPM package layer.
• Incorporates changes from chore: remove references to obsolete restoreScroll axe-core option accessibility-insights-web#6448 and chore: remove unnecessary axe-config rules accessibility-insights-web#6449

Testing

Besides the PR checklist, I validated that a local build of the scan package against test site https://www.catalog.update.microsoft.com/Home.aspx produced a report consistent with [email protected]'s results (no violations), where previously the service reported a slightly distinct set of errors (one violation of the empty-table-header rule, which was accidentally omitted from rule-exclusions.ts during the 4.6.3 update).

Pull request checklist

• Addresses an existing issue: Partially addresses [Feature Request] Axe-core rules should be consistent between service and web #571
• Added relevant unit test for your changes. (yarn test)
• Verified code coverage for the changes made. Check coverage report at: <rootDir>/test-results/unit/coverage
• Ran precheckin (yarn precheckin)
• Validated in an Azure resource group