Add comprehensive tests for formatter classes, services, and utilities

- Introduced tests for various formatter classes including TextFormatter, DurationFormatter, SizeFormatter, DateFormatter, and more to ensure correct formatting behavior.
- Added tests for service classes such as FileTreeService, MetadataService, and RenameService, covering directory validation, metadata extraction, and file renaming functionalities.
- Implemented utility tests for LanguageCodeExtractor, PatternExtractor, and FrameClassMatcher to validate their extraction and matching capabilities.
- Updated test cases to use datasets for better maintainability and clarity.
- Enhanced error handling tests to ensure robustness against missing or invalid data.

renamer/constants/__init__.py

@@ -0,0 +1,45 @@
+"""Constants package for Renamer.
+
+This package contains constants split into logical modules:
+- media_constants.py: Media type definitions (MEDIA_TYPES)
+- source_constants.py: Video source types (SOURCE_DICT)
+- frame_constants.py: Resolution/frame classes (FRAME_CLASSES)
+- moviedb_constants.py: Movie database identifiers (MOVIE_DB_DICT)
+- edition_constants.py: Special edition types (SPECIAL_EDITIONS)
+- lang_constants.py: Language-related constants (SKIP_WORDS)
+- year_constants.py: Year validation (CURRENT_YEAR, MIN_VALID_YEAR, etc.)
+- cyrillic_constants.py: Cyrillic character normalization (CYRILLIC_TO_ENGLISH)
+"""
+
+# Import from all constant modules
+from .media_constants import MEDIA_TYPES
+from .source_constants import SOURCE_DICT
+from .frame_constants import FRAME_CLASSES, NON_STANDARD_QUALITY_INDICATORS
+from .moviedb_constants import MOVIE_DB_DICT
+from .edition_constants import SPECIAL_EDITIONS
+from .lang_constants import SKIP_WORDS
+from .year_constants import CURRENT_YEAR, MIN_VALID_YEAR, YEAR_FUTURE_BUFFER, is_valid_year
+from .cyrillic_constants import CYRILLIC_TO_ENGLISH
+
+__all__ = [
+    # Media types
+    'MEDIA_TYPES',
+    # Source types
+    'SOURCE_DICT',
+    # Frame classes
+    'FRAME_CLASSES',
+    'NON_STANDARD_QUALITY_INDICATORS',
+    # Movie databases
+    'MOVIE_DB_DICT',
+    # Special editions
+    'SPECIAL_EDITIONS',
+    # Language constants
+    'SKIP_WORDS',
+    # Year validation
+    'CURRENT_YEAR',
+    'MIN_VALID_YEAR',
+    'YEAR_FUTURE_BUFFER',
+    'is_valid_year',
+    # Cyrillic normalization
+    'CYRILLIC_TO_ENGLISH',
+]