Mock

Mock

Intro

Mocking is required when you want to just create some test objects and their dependency on the test object itself.

It goes hand in hand with Stubs and Mocking.

I do feel like I still haven't grasp its actual understanding yet but I'm trying to learn as much as possible around Dependency injection via mocking or stubing.

You can specify Mocking certain objects or classes / structs because testing can't be done on them individually as a unit.
One case was related to User Notifications being not able to test in unit tests.

So if the Production class is defined like this.

// Implementation Production Classes

protocol CustomControllerType {

	var viewModel: CustomViewModelProtocol
	var rx: RxSwift.Reactive<Project.Custom.Controller> { .init(Custom.Controller() )}
	
	func configure(for session: Sessionable, viewModelType: CustomViewModelProtocol.Type)		
		
}

protocol CustomViewModelProtocol { 
	var Input init(context: Sessionable, customStorage: customMetadataStorageType, userDefaults: UserDefaults)
    var input: CustomViewModel.Input { get }
    var output: CustomViewModel.Output { get }
    var customCoordinator: RxCustomCoordinatorProtocol { get }
    var disposeBag: DisposeBag { get }
    
}

class ProductionProject.CustomViewModel : CustomViewModelProtocol {
    public let input: Input
    public let output: Output
	public let customCoordinator: RxCustomCoordinatorProtocol
	    
	public required init(context: Sessionable,
                         customStorage: customMetadataStorageType,
                         userDefaults: UserDefaults = .standard) {
                         
        self.customCoordinator = customCoordinator().rx
        let listSectionsDriver = Observable
		.create{ }.asDriver(onErrorJustReturn: [])

		self.input = Input(customTypeGlobalAction: PublishSubject<CustomActionType>().asObserver(),
       refreshAction: PublishSubject<Void>().asObserver(),
       shouldDisplaySomething: PublishSubject<Bool>.asObserver())


           
		self.output = Output(
		listSections: listSectionsDriver,
		customState: PublishSubject<CustomSection>().asDriver(),
		summaryMessage: .empty(),
		confirmCancel: .empty() )
    
    }
}

// MARK: • Input + Output

extension CustomViewModel {
    public struct Input {
        public let customTypeGlobalAction: AnyObserver<CustomActionType>
        public let refreshAction: AnyObserver<Void>
        public let shouldDisplaySomething: AnyObserver<Bool>
    }
    public struct Output {
        public let listSections: Driver<[CustomSection]>
        public let customState: Driver<CustomState>
        public let summaryMessage: Driver<String>
        public let confirmCancel: Signal<Void>
    }
}

// Defining Namespace
public enum Custom { }

public extension Custom {

    final class Controller: CustomControllerType {
	    var rx: Reactive<Custom.Controller> { .init(self) }	
		private(set) var viewModel: CustomViewModelProtocol

		init() {
			self.viewModel = CustomViewModel(context: Sessionable())
		}
		func configure(for session: Sessionable, viewModelType: CustomViewModelProtocol.Type) { 
		}
    }

}

Mock extension for mocking classes.

import RxSwift
import CustomViewModel



extension Mock { 

	class CustomController: CustomControllerType { 
	
		var viewModel: ProjectViewModel.CustomViewModelProtocol = Mock
		.CustomViewModel(
		context: SessionContext(),
		customStorage: Custom.Metadata.Storage(),
		userDefaults: .standard)

		var rx: RxSwift.Reactive<ProductionProject.Custom.Controller> { .init(Custom.Controller()) }
		
		func configure(session: ProductionProject.Sessionable,
		viewModelType: ProductionProject.CustomViewModelProtocol.Type) { }

	
	}
	
	
	class CustomViewModel: CustomViewModelProtocol {
		var input: ProductionProject.CustomViewModel.Input
		var output: ProductionProject.CustomViewModel.Output

		init(context: ProductionProject.Sessionable,
		customStorage: customMetadataStorageType, 
		userDefaults: UserDefaults) {
			
			input = ProductionProject
			.CustomViewModel
			.Input(customTypeGlobalAction: .empty(),
			       refreshAction: .empty(),
			       shouldDisplaySomething: .empty())
			
			
			output = ProductionProject
			.CustomViewModel
			.Output(listSections: .empty(),
					customState: .empty(),
					summaryMessage: .empty(),
					confirmCancel: .empty())
 
		}
	}


}

Less JSON files

In order to effectively test better without adding more fluff, dependencies and assets you would need to carefully choose your objects or make them mutable or utilize @testable into the class/struct code.

MR feedback around unit tests from Jersh - Mentor

i don't think we need to have multiple and nearly identical JSON structures. for the most part, dependencies can usually be built in the code without needing JSON. plus, relying on it and using this strategy won't scale very well because we'll potentially end up with hundreds or thousands of JSON files each with just a small variation in them. and at that point, we'll be spending as much time maintaining JSON files as we will writing actual code

Manual Mocking

iosunittesting | manual-mocking-swift

Core Location Mocking

1. Open Xcode.

2. Choose Product > Test Plan > Edit Test Plan.

3. In the test plan editor pane, choose Configuration.

4. Under Localization, click Simulated Location and choose a location from the menu.

apple dev | simulating-location-in-tests

Quirks

Mock business logic

unit tests are nice but when u have multiple mocks, it gets ![:pita:] to track or do a fast follow ur improved logic into those mocks. And at that point ur thinking why bother writing tests when u have to mock ur implementation as well.

tldr: breakpoints & debug prints ftw to really check wat's wrong in prod env vs testing env.

This came to me when I was chasing a bug which is reproducible in production but not in the unit test mocks, since the business logic which has equality is different compared to other.

Resources

iosunittesting

avanderlee | testing private methods