Add test to PVForecast (#174)

* Add documentation to class_pv_forecast.py.

Added documentation. Beware mostly generated by ChatGPT.

Signed-off-by: Bobby Noelte <b0661n0e17e@gmail.com>

* Add CacheFileStore, datetime and logger utilities.

The `CacheFileStore` class is a singleton-based, thread-safe key-value store for managing
temporary file objects, allowing the creation, retrieval, and management of cache files.

The utility modules offer a flexible logging setup (`get_logger`) and utilities to handle
different date-time formats (`to_datetime`, `to_timestamp`) and timezone detection
(`to_timezone).

- Cache files are automatically valid for the the current date unless specified otherwise.
  This is to mimic the current behaviour used in several classes.
- The logger supports rotating log files to prevent excessive log file size.
- The `to_datetime` and `to_timestamp`functions support a wide variety of input types and formats.
  They provide the time conversion that is e.g. used in PVForecast.

Signed-off-by: Bobby Noelte <b0661n0e17e@gmail.com>

* Improve testability of PVForecast

Improvements for testing of PVForecast
- Use common utility functions to allow for general testing at one spot.
  - to_datetime
  - CacheFileStore
- Use logging instead of print to easily capture in testing.
- Add validation of the json schema for Akkudoktor PV forecast data.
- Allow to create an empty PVForecast instance as base instance for testing.
- Make process_data() complete for filling a PVForecast instance for testing.
- Normalize forecast datetime to timezone of system given in loaded data.
- Do not print report but provide report for test checks.
- Get rid of cache file path using the CachFileStore to automate cache file usage.
- Improved module documentation.

Signed-off-by: Bobby Noelte <b0661n0e17e@gmail.com>

* Add test for PVForecast and newly extracted utility modules.

- Add test for PVForecast
- Add test for CacheFileStore in the new cachefilestore module
- Add test for to_datetime, to_timestamp, to_timezone in the new
  datetimeutil module
- Add test for get_logger in the new logutil module

Signed-off-by: Bobby Noelte <b0661n0e17e@gmail.com>

---------

Signed-off-by: Bobby Noelte <b0661n0e17e@gmail.com>
Co-authored-by: Normann <github@koldrack.com>

tests/test_logutil.py

@@ -0,0 +1,82 @@
+"""Test Module for logutil Module."""
+
+import logging
+import os
+from logging.handlers import RotatingFileHandler
+
+import pytest
+
+from akkudoktoreos.logutil import get_logger
+
+# -----------------------------
+# get_logger
+# -----------------------------
+
+
+@pytest.fixture
+def clean_up_log_file():
+    """Fixture to clean up log files after tests."""
+    log_file = "test.log"
+    yield log_file
+    if os.path.exists(log_file):
+        os.remove(log_file)
+
+
+def test_get_logger_console_logging(clean_up_log_file):
+    """Test logger creation with console logging."""
+    logger = get_logger("test_logger", logging_level="DEBUG")
+
+    # Check logger name
+    assert logger.name == "test_logger"
+
+    # Check logger level
+    assert logger.level == logging.DEBUG
+
+    # Check console handler is present
+    assert len(logger.handlers) == 1
+    assert isinstance(logger.handlers[0], logging.StreamHandler)
+
+
+def test_get_logger_file_logging(clean_up_log_file):
+    """Test logger creation with file logging."""
+    logger = get_logger("test_logger", log_file="test.log", logging_level="WARNING")
+
+    # Check logger name
+    assert logger.name == "test_logger"
+
+    # Check logger level
+    assert logger.level == logging.WARNING
+
+    # Check console handler is present
+    assert len(logger.handlers) == 2  # One for console and one for file
+    assert isinstance(logger.handlers[0], logging.StreamHandler)
+    assert isinstance(logger.handlers[1], RotatingFileHandler)
+
+    # Check file existence
+    assert os.path.exists("test.log")
+
+
+def test_get_logger_no_file_logging(clean_up_log_file):
+    """Test logger creation without file logging."""
+    logger = get_logger("test_logger")
+
+    # Check logger name
+    assert logger.name == "test_logger"
+
+    # Check logger level
+    assert logger.level == logging.INFO
+
+    # Check no file handler is present
+    assert len(logger.handlers) >= 1  # First is console handler (maybe be pytest handler)
+    assert isinstance(logger.handlers[0], logging.StreamHandler)
+
+
+def test_get_logger_with_invalid_level(clean_up_log_file):
+    """Test logger creation with an invalid logging level."""
+    logger = get_logger("test_logger", logging_level="INVALID")
+
+    # Check logger name
+    assert logger.name == "test_logger"
+
+    # Check default logging level is DEBUG
+    assert logger.level == logging.DEBUG