Stubbable protocol for unit testing taken from SwiftBySundell

stubbable.swift

protocol Stubbable: Identifiable {
		static func stub(withID id: UUID) -> Self
}

extension Stubbable {
    func setting<T>(_ keyPath: WritableKeyPath<Self, T>,
                    to value: T) -> Self {
        var stub = self
        stub[keyPath: keyPath] = value
        return stub
    }
}

extension Array where Element: Stubbable {
    static func stub(withCount count: Int) -> Array {
        return (0..<count).map { _ in
            Element.stub(withID: UUID())
        }
    }
}

extension MutableCollection where Element: Stubbable {
    func setting<T>(_ keyPath: WritableKeyPath<Element, T>,
                    to value: T) -> Self {
        var collection = self

        for index in collection.indices {
            let element = collection[index]
            collection[index] = element.setting(keyPath, to: value)
        }

        return collection
    }
}

https://www.swiftbysundell.com/articles/defining-testing-data-in-swift/