在 Swift 中使用异步等待控制时间

Question

Up to now I've been using Combine and the PointFree TestSchedulers https://github.com/pointfreeco/combine-schedulers to "control time" in my tests.

I can make a request and then assert values at certain points in the process without any trouble.

Example...

func testFetchContentSuccess() {
    let queue = TestSchedulerOf<DispatchQueue>(now: .init(.now()))

    let sut = sut(queue: queue.eraseToAnyScheduler())

    XCTAssertEqual(sut.content, .notAsked)

    sut.fetchContent()

    XCTAssertEqual(sut.content, .loading) // this would be impossible without a TestScheulder as the mock endpoint would return immediately.

    queue.advance() // this is what I'm looking for from async await

    assertSnapshot(matching: sut.content, as: .dump)
}

Is there a way to do something similar with async await?

Answer 1

Yes, and it's awesome!

You can just declare test methods as async , then await right in the test method.

So if this test is really about the results of the fetch, it could just be:

func testFetchContentSuccess() {
    let sut = ContentFetcher()

    XCTAssertEqual(sut.content, .notAsked)

    await sut.fetchContent()

    assertSnapshot(matching: sut.content, as: .dump)
}

I have lots of tests that use XCTestExpectation , and most get a lot shorter and easier to read when they're converted to be async/await based.