Unit testing with singletons

Pick all that apply

• 1Choice 1.

  Add a protocol AnalyticsTracking, change the view model to receive it through the initializer instead of calling AnalyticsManager.shared directly, and inject a spy that records calls in tests

• 2Choice 2.

  If you can't change every call site right away, make a replaceable entry point with static var shared (or static var current), swap it in the test setUp, and restore the original instance in tearDown

• 3Choice 3.

  Adding a reset() method to the singleton to prevent state leaking between tests changes production code for the sake of tests, so it's strictly forbidden

• 4Choice 4.

  XCTest launches a new process for every test method, so singleton state resets automatically between tests

• 5Choice 5.

  Since @testable import gives internal access, making the initializer internal instead of private lets tests create a separate instance to verify