Add comprehensive unit tests for ContextNormalizerService

[e0ipso]

Summary

This issue tracks the creation of comprehensive unit tests for the new ContextNormalizerService that will be introduced in issue #34. The tests should ensure the service correctly handles all supported context types and edge cases.

Parent Issue

This issue is a child of #34 - "Refactor: Extract context serialization/deserialization into dedicated service for ab_blocks"

Test Coverage Requirements

Core Functionality Tests

Normalization Tests

• EntityAdapter contexts: Test serialization of entity contexts to entity:{type}={id} format
• PrimitiveInterface contexts: Test JSON encoding of primitive values (string, int, bool, float)
• Language contexts: Test serialization of language objects to language ID
• Mixed context arrays: Test normalization of arrays containing multiple context types
• Empty contexts: Test handling of empty context arrays

Denormalization Tests

• Entity reconstruction: Test recreation of EntityContext objects from serialized format
• Primitive reconstruction: Test recreation of primitive Context objects with proper casting
• Language reconstruction: Test recreation of Language contexts from language IDs
• Invalid data handling: Test graceful handling of malformed serialized data
• Missing entities: Test handling when referenced entities don't exist

Transport Encoding/Decoding Tests

• Base64 encoding roundtrip: Test encodeForTransport() → decodeFromTransport() roundtrips
• JSON error handling: Test handling of invalid JSON during encoding/decoding
• Large data sets: Test performance with large context arrays
• Special characters: Test handling of contexts with special characters or unicode

Edge Cases and Error Handling

Invalid Input Tests

• Null contexts: Test handling of null context values
• Invalid context types: Test handling of unsupported context types
• Corrupted serialized data: Test handling of corrupted serialization strings
• Invalid entity IDs: Test handling of non-existent entity references
• Invalid language codes: Test handling of invalid language identifiers

Boundary Condition Tests

• Empty string values: Test contexts with empty string values
• Zero/false values: Test primitive contexts with falsy values
• Very long strings: Test contexts with extremely long string values
• Special entity types: Test with various entity types (node, user, taxonomy_term, etc.)

Integration with Drupal Services

Mock Dependencies Tests

• TypedDataManager: Mock typed data manager for isolated testing
• EntityTypeManager: Mock entity type manager and storage services
• LanguageManager: Mock language manager for language context tests
• Error scenarios: Test behavior when dependencies throw exceptions

Service Interface Compliance

• NormalizerInterface: Verify proper implementation of normalizer methods
• DenormalizerInterface: Verify proper implementation of denormalizer methods
• Method signatures: Ensure all interface methods have correct signatures
• Return types: Verify correct return types for all methods

Test File Structure

tests/src/Unit/Service/ContextNormalizerServiceTest.php
├── testNormalizeEntityContexts()
├── testNormalizePrimitiveContexts()  
├── testNormalizeLanguageContexts()
├── testNormalizeMixedContexts()
├── testNormalizeEmptyContexts()
├── testDenormalizeEntityContexts()
├── testDenormalizePrimitiveContexts()
├── testDenormalizeLanguageContexts()
├── testDenormalizeInvalidData()
├── testEncodeDecodeTransportRoundtrip()
├── testTransportEncodingEdgeCases()
├── testSupportsNormalization()
├── testSupportsDenormalization()
├── testErrorHandlingWithMissingEntities()
├── testErrorHandlingWithInvalidJson()
└── testBoundaryConditions()

Mock Objects Required

Entity Mocks

// Mock ContentEntityInterface objects
$mockNode = $this->createMock(ContentEntityInterface::class);
$mockUser = $this->createMock(ContentEntityInterface::class);

// Mock EntityStorageInterface
$mockStorage = $this->createMock(EntityStorageInterface::class);

// Mock EntityTypeManagerInterface  
$mockEntityTypeManager = $this->createMock(EntityTypeManagerInterface::class);

Context Mocks

// Mock ContextInterface objects
$mockEntityContext = $this->createMock(ContextInterface::class);
$mockPrimitiveContext = $this->createMock(ContextInterface::class);

// Mock TypedData objects
$mockEntityAdapter = $this->createMock(EntityAdapter::class);
$mockPrimitive = $this->createMock(PrimitiveInterface::class);

Test Data Fixtures

Sample Context Arrays

• Node context: Entity context with node ID 123
• User context: Entity context with user ID 456
• String context: Primitive context with string value "test"
• Integer context: Primitive context with integer value 42
• Boolean context: Primitive context with boolean value true
• Language context: Language context with "en" language code

Expected Serialization Formats

$expectedEntitySerialization = ['entity:node=123'];
$expectedPrimitiveSerialization = ['"test"', '42', 'true'];
$expectedLanguageSerialization = ['"en"'];

Performance Testing

Memory Usage Tests

• Test memory consumption with large context arrays
• Verify no memory leaks during repeated operations
• Test garbage collection of temporary objects

Execution Time Tests

• Benchmark normalization/denormalization performance
• Test with realistic Layout Builder context loads
• Ensure acceptable performance for Ajax requests

Code Coverage Goals

• Line Coverage: 100% of service methods
• Branch Coverage: All conditional paths tested
• Exception Coverage: All exception scenarios tested
• Integration Points: All service dependencies tested

Acceptance Criteria

• All normalization methods have comprehensive unit tests
• All denormalization methods have comprehensive unit tests
• All edge cases and error conditions are tested
• Test coverage meets or exceeds 95%
• All tests pass in isolation and as a suite
• Mock objects properly isolate the service under test
• Performance tests validate acceptable execution times
• Tests follow Drupal testing conventions and standards

Implementation Notes

PHPUnit Annotations

/**
 * Tests the ContextNormalizerService.
 *
 * @group ab_blocks
 * @group ab_tests
 * 
 * @coversDefaultClass \Drupal\ab_blocks\Service\ContextNormalizerService
 */
class ContextNormalizerServiceTest extends UnitTestCase {

Test Dependencies

• Extend UnitTestCase for isolated testing
• Use @covers annotations for accurate coverage reporting
• Mock all external dependencies
• Use data providers for parameterized tests