Publisher value expectation for swift-testing

publisher-expect.swift

import Combine
import Foundation

public extension Publisher {

    func expect(performing action: @escaping () async -> Void, fulfills condition: @escaping (Output) -> Bool, timeout: TimeInterval) async -> Bool {
        let publisher = self
            .handleEvents(receiveSubscription: { _ in
                Task {
                    await action()
                }
            })
            .timeout(.seconds(timeout), scheduler: DispatchQueue.main)

        do {
            for try await value in publisher.values {
                if condition(value) {
                    return true
                }
            }
        } catch { }

        return false
    }
}

public extension Publisher where Output: Equatable {

    func expect(performing action: @escaping () async -> Void, emits expectedValue: Output, timeout: TimeInterval) async -> Bool {
        await expect(performing: action, fulfills: { $0 == expectedValue }, timeout: timeout)
    }
}