Document AST comparison and version strategy

Author: rlerdorf

TOLERANT_TODO.md

@@ -60,6 +60,13 @@ Monitor RFCs merged into php-src and mirror the token/grammar changes, for examp
 - After implementing features, run Phan’s fallback parser tests (`./tests/run_test __FakeSelfFallbackTest`) to ensure parity.
 - Publish updated tags / commit references so Phan can subtree merge the changes into `third_party/phan-tolerant`.
 
+### Verification Strategy
+
+- **AST comparison**: use Phan’s `tools/dump_ast.php` (php-ast) to capture the expected AST for new syntax. Create or extend a tolerant-side helper (instantiate `Microsoft\PhpParser\Parser` and `var_dump` the node tree) so we can diff tolerant output against php-ast.
+- **PHP runtime selection**: on this dev machine we can run `sudo newphp 83`, `sudo newphp 84`, etc. to switch CLI versions; other environments may require Docker images, phpenv, asdf, etc. Record the PHP version used when regenerating fixtures.
+- **Leverage Phan fixtures**: pull feature-specific testcases (e.g. property hooks, asymmetric visibility) from `phan/tests/files/src` into tolerant’s parser tests to validate new constructs.
+- **Run tolerant PHPUnit suites**: keep `vendor/bin/phpunit --testsuite invariants,api` (with `zend.assertions=1`) as a fast regression check while iterating.
+
 ## Next Steps
 
 1. Audit existing fixtures vs php-src 8.3/8.4 syntax to catalogue precise failures.