Covenant API

[danjagnow]

Add support for the Covenant API, which is a new addition to the Game Data APIs for the Shadowlands expansion. See WoW Shadowlands API Update - Covenants, Soulbinds, & More for details about the new APIs.

[willwolfram18]

I'll take a swing at this. Seems like a small and easy enough API set.

[willwolfram18]

@danjagnow wanted to check and see if you'd be cool with some tweaks I was interested in introducing while unit testing this method. Specifically I was looking at doing the following:

• Including Fluent Assertions for some validation of model deserializations
• Tests for different region+locale combos to better exercise some of the other code paths beyond the Region.US and Locale.en_US
  • Not planning to do all combos, but at least get a little more coverage.
• Change up the test case layout for the Covenant API methods, similar to the DI tests
  • Basically looking at trying to bring a little SRP to the unit tests so that 1 class focuses on testing one method (or in this case pair of methods for the region+locale overload).

Let me know your thoughts, don't want to add too much or create fragmentation if you're not on-board.

[danjagnow]

• Adding Fluent Assertions would be good. I use it in my professional work, and I like it. I have just been too lazy to add validations beyond the not-null check. This is particularly important after the PR that migrated from Newtonsoft.Json to System.Text.Json. Previously it was possible to set MissingMemberHandling = MissingMemberHandling.Error for debug builds, which made it much easier to discover cases where the C# models lacked a property that was needed for full deserialization of the JSON. See the note about MissingMemberHandling in the migration guidance for details. Hopefully Add support for MissingMemberHandling to System.Text.Json dotnet/runtime#37483 will get addressed in the future.
• Tests for different combinations of region and locale would be very welcome; again, I've just been too lazy to add these.
• Changing the test case layout is fine with me. I find that the existing layout is fine for the level of testing that is currently being performed, but having a single test class per API may be too coarse-grained when adding the variants you're proposing. Feel free to change it up.