Medium blogpost snippet

TestTask.swift

func test_givenTask_whenExecuted_itUpdatesStatusInSpecificOrder() {
    let task = Task()
    let mockDelegate = MockTaskStatusDelegate()
    task.statusDelegate = mockDelegate

    let downloadingExpectation = self.expectation(description: "status changes to .downloading")
    let processingExpectation = self.expectation(description: "status changes to .processing")
    let finishedExpectation = self.expectation(description: "status changes to .finished")

    mockDelegate.didCall_taskDidChangeStatus = { (_, status) in
        switch status {
        case .downloading:
            downloadingExpectation.fulfill()
        case .processing:
            processingExpectation.fulfill()
        case .finished:
            finishedExpectation.fulfill()
        default:
            XCTFail()
        }
    }

    task.execute()

    wait(for: [downloadingExpectation, processingExpectation, finishedExpectation],
         timeout: 0.5,
         enforceOrder: true)
}