This is needed so that a request is made for each test class when running multiple at once. This way RecordingDownloader records all necessary requests.
This works as long as tests are run sequentially and not in parallel.
Channel mix adjusments and test
Don't accept youtube music mix urls as playlist
Don't override playlistData to keep getInitialPage()
Remove json constants
Indentation
Move thumbnail id exctraction code to getThumbnailUrlFromId
Add test for "My mix" detection to service tests
Use ITEM_COUNT_UNKNOWN everywhere instead of -1 and add some tests
XiangRongLin