* Fixes issue #4067 - Wunderground sensor with alerts exceeds API limits
To avoid hitting the max limit of 500 calls per day, this patch keeps weather conditions being updated each 5 minutes
and weather advisories each 15 minutes.
This formula will result the following:
conditions -> 300 seconds -> 5 minutes -> 12 req/h -> 288 req/day
alerts -> 900 seconds -> 15 minutes -> 4 req/h -> 96 req/day
* Using timedelta in minutes instead seconds
* If no weather advisories were issued, state should return 0 instead Unknown
* Updated to keep on the same if statement
* Revert "Updated to keep on the same if statement"
This reverts commit 0e6a94aa0f.
* Added the ability to Weather Underground to track severe weather alerts
* * Added message on the advisory attr
* Updated tests
* * Making use of guard clause
* Checking multiple_alerts prior loop
* Using a better way to create dict
* Fixed issue to set to None only the object that failed
* Added unittest
* Split update() method to different calls with their one throttle control to minimize API calls
* Updated unittest and make sure the alert sensor will not return 'unknown' status'
* Removed update() method from state property
* Branch rebased and include Weather Underground attribution
* Update wunderground.py
* Clean-up, ordering, constants, and extend of schema
* Put REQUIREMENTS back and re-add line breaks
* Clean-up, ordering, constants, and extend of schema
* Extend platform
