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/year_constants.py

@@ -0,0 +1,20 @@
+"""Year validation constants for filename parsing.
+
+This module contains constants used for validating years extracted from filenames.
+"""
+
+import datetime
+
+# Current year for validation
+CURRENT_YEAR = datetime.datetime.now().year
+
+# Minimum valid year for movies/media (start of cinema era)
+MIN_VALID_YEAR = 1900
+
+# Allow years slightly into the future (for upcoming releases)
+YEAR_FUTURE_BUFFER = 10
+
+# Valid year range: MIN_VALID_YEAR to (CURRENT_YEAR + YEAR_FUTURE_BUFFER)
+def is_valid_year(year: int) -> bool:
+    """Check if a year is within the valid range for media files."""
+    return MIN_VALID_YEAR <= year <= CURRENT_YEAR + YEAR_FUTURE_BUFFER