Testing Guidelines

Hi @joshuatf ,

Apart from reviewing the code changes, please make sure to review the testing instructions (Guide) and verify that relevant tests (E2E, Unit, Integration, etc.) have been added or updated as needed.

Reminder: PR reviewers are required to document testing performed. This includes:

• 🖼️ Screenshots or screen recordings.
• 📝 List of functionality tested / steps followed.
• 🌐 Site details (environment attributes such as hosting type, plugins, theme, store size, store age, and relevant settings).
• 🔍 Any analysis performed, such as assessing potential impacts on environment attributes and other plugins, conducting performance profiling, or using LLM/AI-based analysis.

⚠️ Within the testing details you provide, please ensure that no sensitive information (such as API keys, passwords, user data, etc.) is included in this public issue.

sequenceDiagram
    participant VarStore as Variable Product Data Store
    participant CallbackUtil
    participant WPFilter as global $wp_filter

    VarStore->>CallbackUtil: get_hook_callback_signatures(hook_name)
    CallbackUtil->>WPFilter: read $wp_filter[hook_name]
    WPFilter-->>CallbackUtil: callbacks grouped by priority

    loop per priority
        loop per callback
            CallbackUtil->>CallbackUtil: get_callback_signature(callback)
            alt function name
                Note right of CallbackUtil: "functionName"
            else class method
                Note right of CallbackUtil: "ClassName::method"
            else closure
                Note right of CallbackUtil: "Closure@hash"
            else invokable object
                Note right of CallbackUtil: "ClassName::__invoke"
            else
                Note right of CallbackUtil: "serialize(callback)"
            end
            CallbackUtil-->>VarStore: signatures grouped by priority
        end
    end

    VarStore->>VarStore: include signatures in variation price hash

Pre-merge checks and finishing touches

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Claude encountered an error —— View job

Backwards Compatibility Review

Analyzing PR #61779 for breaking changes and ecosystem impacts...

Todo List

• Read and analyze changed files
• Assess public API changes
• Check hook modifications
• Evaluate price hash generation changes
• Consider ecosystem/extension impacts
• Review CodeRabbit feedback
• Provide BC assessment summary

Claude finished @Konamiman's task —— View job

Backwards Compatibility Review

Comprehensive analysis of PR #61779 for breaking changes and ecosystem impacts.

Summary

Risk Level: LOW

This PR introduces a new utility class and modifies internal price hash generation logic to fix a caching bug. The changes are backwards compatible with minimal ecosystem risk. The price hash format change is intentional and necessary to fix the bug—existing cached transients will naturally invalidate and rebuild with correct values.

Key Points:

• New CallbackUtil class adds public API but doesn't modify existing APIs
• get_price_hash is a protected method (internal implementation detail)
• Price hash format change will cause one-time cache invalidation (expected behavior)
• No hooks added, removed, or modified in their external contracts
• Defensive coding added for corrupted $wp_filter structures

Detailed Analysis

1. Public API Changes ✅ Safe - New additions only

New Class: Automattic\WooCommerce\Utilities\CallbackUtil (final)

File: plugins/woocommerce/src/Utilities/CallbackUtil.php

Two new public static methods:

// Line 26-55
public static function get_callback_signature( $callback ): string

• Purpose: Generates stable signature strings for PHP callbacks
• Parameters: callable|mixed $callback
• Returns: string - Normalized callback signature
• BC Impact: None - new method, no conflicts
• @SInCE: 10.4.0

// Line 72-99
public static function get_hook_callback_signatures( string $hook_name ): array

• Purpose: Returns array of callback signatures for a hook, organized by priority
• Parameters: string $hook_name
• Returns: array<int, array<string>> - Priority => signatures mapping
• BC Impact: None - new method, no conflicts
• @SInCE: 10.4.0
• Note: Includes defensive handling for corrupted $wp_filter structures (lines 81-93)

Assessment: These are new utility methods with no conflicts with existing APIs. Extensions can safely adopt them.

2. Modified Internal Implementation ✅ Safe - Protected method

File: plugins/woocommerce/includes/data-stores/class-wc-product-variable-data-store-cpt.php:488-509

Method: WC_Product_Variable_Data_Store_CPT::get_price_hash() (protected)

Changes:

- Direct access to global $wp_filter
- Manual iteration over priorities and callbacks
- Using wp_list_pluck() to extract 'function' keys
- Serializing entire callback objects (buggy behavior)

+ Using CallbackUtil::get_hook_callback_signatures()
+ Stable callback signatures independent of object state
+ Defensive handling of corrupted $wp_filter

BC Assessment:

• ✅ Method visibility: protected - not part of public API contract
• ✅ Method signature unchanged: protected function get_price_hash( &$product, $for_display = false )
• ✅ Return type unchanged: string (MD5 hash)
• ⚠️ Hash value will change (but this is the intended fix)

Price Hash Format Change:

Before (buggy):

$price_hash[ $filter_name ][] = array_values( wp_list_pluck( $callbacks, 'function' ) );
// Serialized entire callback objects including dynamic properties

After (fixed):

$price_hash[ $filter_name ] = CallbackUtil::get_hook_callback_signatures( $filter_name );
// Returns: array( priority => array( 'ClassName::method', 'function_name', ... ) )

Impact:

• First request after deployment: All variation price transients (wc_var_prices_{product_id}) will invalidate
• Subsequent requests: Stable cache keys enable proper transient reuse
• This is the intended behavior - the bug was that hashes changed on every request

3. Hook Modifications ✅ No changes

Checked hooks:

• woocommerce_variation_prices_price - Not modified
• woocommerce_variation_prices_regular_price - Not modified
• woocommerce_variation_prices_sale_price - Not modified
• woocommerce_get_variation_prices_hash - Not modified

Assessment: No hooks added, removed, or changed. Filter contracts remain identical.

4. Ecosystem Impact Analysis ✅ Minimal risk

Extensions hooking into variation price filters:

The three price filters analyzed:

• woocommerce_variation_prices_price
• woocommerce_variation_prices_regular_price
• woocommerce_variation_prices_sale_price

Common Extension Patterns:

1. WooCommerce Subscriptions - Hooks these filters for subscription pricing

   • Impact: None - filter behavior unchanged, will benefit from cache fix

2. WooCommerce Memberships - Modifies prices based on membership levels

   • Impact: None - dynamic pricing will now cache correctly

3. Custom pricing plugins - Add discounts, markups, role-based pricing

   • Impact: None - existing callbacks continue working
   • Benefit: Object property changes no longer break caching

4. Payment gateways - Typically don't hook variation price filters

   • Impact: None

Closure Usage Warning:

Per CallbackUtil.php:64-65:

Note: Closure signatures use spl_object_hash(), which will differ between requests.

• Extensions using closures for these filters will still experience cache invalidation on each request
• Recommendation: Extensions should use named functions or class methods, not closures
• This is a limitation, not a regression (closures were already problematic)

5. Testing & Validation ✅ Comprehensive

Test Coverage: plugins/woocommerce/tests/php/src/Utilities/CallbackUtilTest.php (425 lines, 18 test methods)

Key test scenarios:

• ✅ Function callbacks: test_get_callback_signature_with_function_name()
• ✅ Instance methods: test_get_callback_signature_with_instance_method()
• ✅ Static methods: test_get_callback_signature_with_static_method()
• ✅ Closures: test_get_callback_signature_different_closures()
• ✅ Invokable objects: test_get_callback_signature_with_invokable_object()
• ✅ Consistency across instances: test_get_callback_signature_consistent_across_instances()
• ✅ Multiple callbacks per hook: test_get_hook_callback_signatures_with_multiple_callbacks()
• ✅ Corrupted $wp_filter: test_get_hook_callback_signatures_with_corrupted_wp_filter() (line 348)
• ✅ Corrupted priority entries: test_get_hook_callback_signatures_with_corrupted_priority_entry() (line 371)
• ✅ Corrupted callback entries: test_get_hook_callback_signatures_with_corrupted_callback_entry() (line 399)

Defensive Coding: Lines 81-93 and 108-117 in CallbackUtil.php handle corrupted $wp_filter structures gracefully.

6. CodeRabbit Review Feedback ✅ Addressed

Review Comment: Add defensive coding for corrupted $wp_filter structure

Resolution: Commit 8bb4524a62 - "Add robustness against corrupted $wp_filter"

• Added validation in is_valid_wp_filter_priority_entry() (lines 108-117)
• Fallback to serialization for invalid structures (lines 81-93)
• Comprehensive test coverage for edge cases

Testing Focus

Critical Regression Testing Areas:

1. Variable Product Price Display (High Priority)

   • Load product pages with variable products
   • Verify price ranges display correctly
   • Test with/without active filters on the three price hooks
   • Expected: Prices display correctly, faster on subsequent loads

2. Transient Invalidation Behavior (High Priority)

   • Monitor wc_var_prices_{product_id} transients
   • Add/remove hooks to price filters dynamically
   • Expected: Hash changes when hooks change, stable when hooks unchanged

3. Extension Compatibility (Medium Priority)

   • Test with WooCommerce Subscriptions
   • Test with WooCommerce Memberships
   • Test with dynamic pricing plugins
   • Expected: All continue functioning, benefit from stable caching

4. Performance Validation (Medium Priority)

   • Measure price calculation time for variable products with many variations
   • First load vs. cached load
   • Expected: Significant performance improvement on cached loads

Test Steps (from PR description):

1. Create/identify variable product with many variations
2. Apply test snippet (adds filter that modifies object properties)
3. Run wp eval 'WooPriceHashTester::test_price_hash(<id>, true);'
4. Expected: Hash1 === Hash2 (stable across property changes)
5. Run again with false parameter
6. Expected: Same hashes, much faster (using cache)
7. Verify shop display and checkout still work correctly

Cache Migration Considerations

One-Time Impact:

When this code deploys to production:

1. All existing variation price transients will have old hash format in keys
2. First request after deployment will not find matching hash in transient
3. Prices will recalculate (correct behavior)
4. New transient stored with stable hash
5. Subsequent requests use cache (performance improvement)

No manual cache clearing needed - natural invalidation occurs automatically.

Confidence

95% - No breaking changes detected.

Justification:

• All modified code is internal/protected (not public API)
• New utility class adds functionality without conflicts
• Comprehensive test coverage including edge cases
• Price hash format change is intentional fix, not regression
• Defensive coding handles corrupted data structures
• No hook contract modifications
• Extensions benefit from fix without code changes

Remaining 5% uncertainty:

• Edge cases with exotic callback types not covered in tests
• Potential unforeseen extension patterns that inspect $wp_filter directly for these specific hooks
• Performance impact on sites with thousands of variable products (should be positive but not measured)

Recommendations

1. ✅ Approve for merge - No blocking BC concerns
2. 📊 Monitor post-deployment:
   • Transient regeneration patterns
   • Price display accuracy
   • Cache hit rates
   • Error logs for callback signature failures
3. 📝 Documentation suggestion: Add developer note to Woo docs about avoiding closures in price filters for optimal caching

Conclusion

This PR is backwards compatible. The price hash format change is an intentional bug fix that will cause one-time cache invalidation—this is correct behavior. Extensions hooking the variation price filters require no code changes and will automatically benefit from the stable caching. The new CallbackUtil class provides useful utilities for the ecosystem without introducing conflicts.

Claude finished @Konamiman's task —— View job

Backwards Compatibility Review

Comprehensive analysis of PR #61779 for breaking changes and ecosystem impacts.

Summary

Risk Level: LOW

This PR introduces a new utility class and modifies internal price hash generation logic to fix a caching bug. The changes are backwards compatible with minimal ecosystem risk. The price hash format change is intentional and necessary to fix the bug—existing cached transients will naturally invalidate and rebuild with correct values.

Key Points:

• New CallbackUtil class adds public API but doesn't modify existing APIs
• get_price_hash is a protected method (internal implementation detail)
• Price hash format change will cause one-time cache invalidation (expected behavior)
• No hooks added, removed, or modified in their external contracts
• Defensive coding added for corrupted $wp_filter structures

Detailed Analysis

1. Public API Changes ✅ Safe - New additions only

New Class: Automattic\WooCommerce\Utilities\CallbackUtil (final)

File: plugins/woocommerce/src/Utilities/CallbackUtil.php

Two new public static methods:

// Line 26-55
public static function get_callback_signature( $callback ): string

• Purpose: Generates stable signature strings for PHP callbacks
• Parameters: callable|mixed $callback
• Returns: string - Normalized callback signature
• BC Impact: None - new method, no conflicts
• @SInCE: 10.4.0

// Line 72-99
public static function get_hook_callback_signatures( string $hook_name ): array

• Purpose: Returns array of callback signatures for a hook, organized by priority
• Parameters: string $hook_name
• Returns: array<int, array<string>> - Priority => signatures mapping
• BC Impact: None - new method, no conflicts
• @SInCE: 10.4.0
• Note: Includes defensive handling for corrupted $wp_filter structures (lines 81-93, 108-117)

Assessment: These are new utility methods with no conflicts with existing APIs. Extensions can safely adopt them.

2. Modified Internal Implementation ✅ Safe - Protected method

File: plugins/woocommerce/includes/data-stores/class-wc-product-variable-data-store-cpt.php:488-509

Method: WC_Product_Variable_Data_Store_CPT::get_price_hash() (protected)

Changes:

- Direct access to global $wp_filter
- Manual iteration over priorities and callbacks
- Using wp_list_pluck() to extract 'function' keys
- Serializing entire callback objects (buggy behavior)

+ Using CallbackUtil::get_hook_callback_signatures()
+ Stable callback signatures independent of object state
+ Defensive handling of corrupted $wp_filter

BC Assessment:

• ✅ Method visibility: protected - not part of public API contract
• ✅ Method signature unchanged: protected function get_price_hash( &$product, $for_display = false )
• ✅ Return type unchanged: string (MD5 hash)
• ⚠️ Hash value will change (but this is the intended fix)

Price Hash Format Change:

Before (buggy):

$price_hash[ $filter_name ][] = array_values( wp_list_pluck( $callbacks, 'function' ) );
// Serialized entire callback objects including dynamic properties

After (fixed):

$price_hash[ $filter_name ] = CallbackUtil::get_hook_callback_signatures( $filter_name );
// Returns: array( priority => array( 'ClassName::method', 'function_name', ... ) )

Impact:

• First request after deployment: All variation price transients (wc_var_prices_{product_id}) will invalidate
• Subsequent requests: Stable cache keys enable proper transient reuse
• This is the intended behavior - the bug was that hashes changed on every request

3. Hook Modifications ✅ No changes

Checked hooks:

• woocommerce_variation_prices_price (line 312) - Not modified
• woocommerce_variation_prices_regular_price (line 313) - Not modified
• woocommerce_variation_prices_sale_price (line 314) - Not modified
• woocommerce_variation_prices_array (lines 379, 395, 402) - Not modified
• woocommerce_variation_prices (lines 445, 448) - Not modified
• woocommerce_get_variation_prices_hash (line 508) - Not modified

Assessment: No hooks added, removed, or changed. Filter contracts remain identical.

4. Ecosystem Impact Analysis ✅ Minimal risk

Extensions hooking into variation price filters:

The three price filters analyzed:

• woocommerce_variation_prices_price
• woocommerce_variation_prices_regular_price
• woocommerce_variation_prices_sale_price

Common Extension Patterns:

1. WooCommerce Subscriptions - Hooks these filters for subscription pricing

   • Impact: None - filter behavior unchanged, will benefit from cache fix

2. WooCommerce Memberships - Modifies prices based on membership levels

   • Impact: None - dynamic pricing will now cache correctly

3. Custom pricing plugins - Add discounts, markups, role-based pricing

   • Impact: None - existing callbacks continue working
   • Benefit: Object property changes no longer break caching

4. Payment gateways - Typically don't hook variation price filters

   • Impact: None

Closure Usage Limitation:

Per CallbackUtil.php:64-65:

Note: Closure signatures use spl_object_hash(), which will differ between requests.

• Extensions using closures for these filters will still experience cache invalidation on each request
• Recommendation: Extensions should use named functions or class methods, not closures
• This is a limitation, not a regression (closures were already problematic)

5. Testing & Validation ✅ Comprehensive

Test Coverage: plugins/woocommerce/tests/php/src/Utilities/CallbackUtilTest.php (425 lines, 18 test methods)

Key test scenarios:

• ✅ Function callbacks: test_get_callback_signature_with_function_name()
• ✅ Instance methods: test_get_callback_signature_with_instance_method()
• ✅ Static methods: test_get_callback_signature_with_static_method()
• ✅ Closures: test_get_callback_signature_different_closures()
• ✅ Invokable objects: test_get_callback_signature_with_invokable_object()
• ✅ Consistency across instances: test_get_callback_signature_consistent_across_instances()
• ✅ Multiple callbacks per hook: test_get_hook_callback_signatures_with_multiple_callbacks()
• ✅ Corrupted $wp_filter: test_get_hook_callback_signatures_with_corrupted_wp_filter() (line 348)
• ✅ Corrupted priority entries: test_get_hook_callback_signatures_with_corrupted_priority_entry() (line 371)
• ✅ Corrupted callback entries: test_get_hook_callback_signatures_with_corrupted_callback_entry() (line 399)

Defensive Coding: Lines 81-93 and 108-117 in CallbackUtil.php handle corrupted $wp_filter structures gracefully.

6. CodeRabbit Review Feedback ✅ Addressed

Review Comment: Add defensive coding for corrupted $wp_filter structure

Resolution: Commit 8bb4524a62 - "Add robustness against corrupted $wp_filter"

• Added validation in is_valid_wp_filter_priority_entry() (lines 108-117)
• Fallback to serialization for invalid structures (lines 81-93)
• Comprehensive test coverage for edge cases

Testing Focus

Critical Regression Testing Areas:

1. Variable Product Price Display (High Priority)

   • Load product pages with variable products
   • Verify price ranges display correctly
   • Test with/without active filters on the three price hooks
   • Expected: Prices display correctly, faster on subsequent loads

2. Transient Invalidation Behavior (High Priority)

   • Monitor wc_var_prices_{product_id} transients
   • Add/remove hooks to price filters dynamically
   • Expected: Hash changes when hooks change, stable when hooks unchanged

3. Extension Compatibility (Medium Priority)

   • Test with WooCommerce Subscriptions
   • Test with WooCommerce Memberships
   • Test with dynamic pricing plugins
   • Expected: All continue functioning, benefit from stable caching

4. Performance Validation (Medium Priority)

   • Measure price calculation time for variable products with many variations
   • First load vs. cached load
   • Expected: Significant performance improvement on cached loads

Test Steps (from PR description):

1. Create/identify variable product with many variations
2. Apply test snippet (adds filter that modifies object properties)
3. Run wp eval 'WooPriceHashTester::test_price_hash(<id>, true);'
4. Expected: Hash1 === Hash2 (stable across property changes)
5. Run again with false parameter
6. Expected: Same hashes, much faster (using cache)
7. Verify shop display and checkout still work correctly

Cache Migration Considerations

One-Time Impact:

When this code deploys to production:

1. All existing variation price transients will have old hash format in keys
2. First request after deployment will not find matching hash in transient
3. Prices will recalculate (correct behavior)
4. New transient stored with stable hash
5. Subsequent requests use cache (performance improvement)

No manual cache clearing needed - natural invalidation occurs automatically.

Confidence

95% - No breaking changes detected.

Justification:

• All modified code is internal/protected (not public API)
• New utility class adds functionality without conflicts
• Comprehensive test coverage including edge cases
• Price hash format change is intentional fix, not regression
• Defensive coding handles corrupted data structures
• No hook contract modifications
• Extensions benefit from fix without code changes

Remaining 5% uncertainty:

• Edge cases with exotic callback types not covered in tests
• Potential unforeseen extension patterns that inspect $wp_filter directly for these specific hooks
• Performance impact on sites with thousands of variable products (should be positive but not measured)

Recommendations

1. ✅ Approve for merge - No blocking BC concerns
2. 📊 Monitor post-deployment:
   • Transient regeneration patterns
   • Price display accuracy
   • Cache hit rates
   • Error logs for callback signature failures
3. 📝 Documentation suggestion: Add developer note to Woo docs about avoiding closures in price filters for optimal caching

Conclusion

This PR is backwards compatible. The price hash format change is an intentional bug fix that will cause one-time cache invalidation—this is correct behavior. Extensions hooking the variation price filters require no code changes and will automatically benefit from the stable caching. The new CallbackUtil class provides useful utilities for the ecosystem without introducing conflicts.