Test mapping to nullable or filtering + mapping

TestFilterMapCombine.swift

import Combine

struct PointOfSaleEntryPoint {}

let isBetaFeatureEnabled = PassthroughSubject<Bool, Never>()
let isEligibleForPOS = PassthroughSubject<Bool, Never>()
let posViewModel =
Publishers.CombineLatest(isBetaFeatureEnabled, isEligibleForPOS)
//    // Map to optional value
//    // Output: 
//    // posViewModel: nil
//    // posViewModel: Optional(__lldb_expr_38.PointOfSaleEntryPoint())
//    // posViewModel: nil
//    .map { isBetaFeatureEnabled, isEligibleForPOS -> PointOfSaleEntryPoint? in
//        if isBetaFeatureEnabled && isEligibleForPOS {
//            return PointOfSaleEntryPoint()
//        } else {
//            return nil
//        }
//    }
    // Filter + map
    // Output: 
    // posViewModel: PointOfSaleEntryPoint()
    .filter { isBetaFeatureEnabled, isEligibleForPOS in
        isBetaFeatureEnabled && isEligibleForPOS
    }
    .map { _ in
        PointOfSaleEntryPoint()
    }

posViewModel
    .sink { viewModel in
        print("posViewModel: \(viewModel)")
    }

// Expected: nil view model
isBetaFeatureEnabled.send(true)
isEligibleForPOS.send(false)

// Expected: non-nil view model
isEligibleForPOS.send(true)

// Expected: nil view model
isBetaFeatureEnabled.send(false)