View Controller Dependency Injection Test

ExampleViewControllerTest.swift

class ExampleViewControllerTest: XCTestCase {
    class FakeDependableService: DependableService {
        var lastRequestParameter: String?
        var stubbedResponse: DependableResponse?

        init() {
            super.init()

            self.lastRequestParameter = ""
            self.stubbedResponse = nil
        }

        override func attemptCall(param: String?) -> Future<DependableResponse> {
            self.lastRequestParameter = param

            return Future(success: stubbedResponse!)
        }
    }

    var dependableService = FakeDependableService()

    func testClickCallButton_makesCallToService_successResponse() {
        dependableService.stubbedResponse = DependableResponse.Success("You win!")

        let controller = ExampleViewController.loadFromStoryboard(dependableService)
        assertThat(controller.view, present())

        UIWindow.present(viewController: controller) { () in
            controller.didTapCallButton(NSObject())
            
            assertThat(dependableService.lastRequestParameter, presentAnd(equalTo("Do I win?")))
            assertThat(controller.presentedViewController, presentAnd(instanceOf(NextViewController)))
        }
    }
}