Introduce ViewModel for RssFeed*Activity
Closes #1894 (closed)
Testing instructions
This MR refactors the whole RSS Feed system.
Access RSS Feeds-screen in the "action overflow" (3 dots-icon) in the app bar of the Blogs activity.
It is at all times during testing -- like after actions taken, events occuring etc -- relevant to rotate the device and ensure that:
- Text entered in fields, switches toggled etc remain so
- Visibility of progressbars and buttons are the same
- Labels on buttons remain the same
- Opened dialog boxes remain so
Import a feed
- Tap Plus-icon in the app bar
- Enter a feed URL
- example valid feed: https://briarproject.org/news/index.xml
- invalid feed (a HTML page): https://briarproject.org
- Tap import
- Wait for import to succeed, and to be returned to RSS Feeds-screen.
- or expect import-failed dialog, if feed was invalid
- Verify that successfully added feed appears in list on RSS Feeds-screen.
Be impatient, after "Tap import" above:
- Return to previous screen ◁
- Wait for successfully added feed to appear in list
- Or, in the case of an invalid feed, expect import-failed dialog.
Be even more impatient, after "Tap import" above:
- Return to previous screen ◁
- Tap Plus-icon to add a new feed while the first one is being processed
- Expect the progressbar to be visible
- Expect to be returned to RSS Feeds-screen once ongoing import is successful