Testing Asynchronous Code in Swift 5.5
summary
Refactors a Combine-based app to Swift 5.5 concurrency, showing concrete testable changes: replacing completion handlers with async/await, using withCheckedContinuation to test existing Combine or escaping-completion code without changing it, mocking network calls via AsyncStream plus a URLProtocol interceptor, and a reusable timeout Task that phases out waitForExpectations. Demonstrates parsing 999 meme templates down to ~799, running async let/sink let to observe effects, and when tests hang how to cancel or finish continuations so failures are meaningful.
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chapters (9)
- 0:00Introduction and background
- 1:44Refactoring from Combine to async/await
- 6:08Testing structured concurrency basics
- 9:22Challenges with async/await in XCTest
- 14:14Testing tasks and cancellation
- 19:41Using task continuation for legacy code
- 20:02Mocking network calls with async stream
- 27:49Implementing timeout for async tests
- 29:55Final thoughts and future of async testing
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