Swift_Testing

Swift Testing

Intro

New framework by apple which would be more expressive and is more aligned with what apple has started pushing for swift concurrency manifesto + macros in recent years.
For me it seems like a first party / class citizen treatment finally from apple to its testing framework tools.

Code

Renames

apple | Migration guide

Test Throws

#expect(throws: URLParserPlayerError.self) {
	try urlResolver.isTemplateValid(resolverInput)
}

#expect {
	try urlResolver.isTemplateValid(resolverInput)
}
throws: { error in
	if let errorParsed = error as? URLParserPlayerError {
		#expect(errorParsed != nil)
		#expect(errorDescription == errorParsed.description)
	}
}

Problems

How to Wait

wait(for:timeout:)

apple | wait

Combine

Combine reactive paradigm testing with expectations to confirmation

@Test
func imageRetrieved() async {
  var cancellable: AnyCancellable?
  await confirmation { imageRetrieved in
    cancellable = viewModel.$image.dropFirst().sink { _ in
      // Do nothing on completion.
    } receiveValue: {
      #expect($0 != nil)
      imageRetrieved()
    }
  }
  cancellable?.cancel()
}

Converted to use AsyncSequence on the publishers

@Test
func imageRetrieved() async {
    let value = await viewModel.$image.values.first()
    #expect(value != nil)
}

With this extension to simplify the call to first(where:):

extension AsyncSequence {
    func first() async rethrows -> Element? {
        try await first(where: { _ in true})
    }
}

SO | test combine publishers

Reference

swift with majid | swift testing basics

avanderlee | swift testing