gistfile1.txt

import Foundation
import Combine
import XCTest

class Sut {
    
    private var bag = Set<AnyCancellable>()
    
    var triggerSubject = PassthroughSubject<Void, Never>()

    func start() {
        Swift.print("I'm starting doing a work")
        doWork()
            .receive(on: DispatchQueue.main)
            .sink(receiveValue: { [weak self] value in
                Swift.print("I'm done: \(value)")
                self?.triggerSubject.send()
            })
            .store(in: &bag)
    }
    
    func doWork() -> Future<Int, Never> {
        return Future { promise in
            promise(.success(100500))
        }
    }
}

class TestCase: XCTestCase {
    
    var sut: Sut!
    var bag = Set<AnyCancellable>()
    
    override func setUpWithError() throws {
        sut = Sut()
    }
    
    override func tearDownWithError() throws {
        sut = nil
    }
    
    func test() {
        var subjectTriggered = false
        
        sut.triggerSubject.sink(receiveValue: { _ in
            Swift.print("Triggered")
            subjectTriggered = true
        })
        .store(in: &bag)
        
        XCTAssertFalse(subjectTriggered)
        Swift.print("Please, start")
        sut.start()
        XCTAssertTrue(subjectTriggered)
    }
    
}

TestCase.defaultTestSuite.run()

//let sut = Sut()
//sut.start()