[Part 5] Networking Refactor - CardPayment unit tests

[scannillo]

Reason for changes

This PR re-writes our CardPaymentsTests based on the source code changes introduced in this series of networking layer refactor PRs.

Summary of changes

• Add tests for:
  • CheckoutOrdersAPI
  • VaultPaymentsTokenAPI
• Update tests for:
  • CardClient (now relies on mocked <PPassAPI> classes to stub network responses)
  • ConfirmPaymentSourceRequest (now it's only a model type, versus before it had many functions)
• Move mocks into CardPaymentTests/Mocks dir
• Add mocks for:
  • CheckoutOrdersAPI and VaultPaymentTokensAPI for use in CardClient_Tests
  • Repurpose CardResponses file of sample JSON responses to be raw ConfirmPaymentSourceReponse types

Next

• We can merge to main now! Tests are passing 😎
• Follow ups which can happen on main:
  • Encapsulate JSONEncoder functionality into wrapper class
  • Rename APIClient --> NetworkingClient
  • Re-organize file structure
  • Align naming convention for request model types

Checklist

• ~Added a changelog entry~

Authors

@scannillo