InjectStory

Simple dependency injection framework for Swift

Usage

• create a protocol

protocol AnimalSound {
    func makeSound() -> String
}

• add implementation for protocol

class CatViewModel: AnimalSound {
    func makeSound() -> String{
        return "meow"
    }
}

• add static variable to class where you want use dependency injection. Remember to use protocol type as Injection type.

static let viewModelInjection = Injection<AnimalSound>(CatViewModel())

• inject dependency

let viewModel = viewModelInjection.inject()

• if you want different view model object use

ViewController.viewModelInjection.overrideOnce = { MockAnimalSound() }

(where MockAnimalSound must implement AnimalSound protocol)

Installation

Use the CocoaPods.

Add to your Podfile

pod 'InjectStory'

and then call

pod install

and import

import InjectStory

Example

//  ViewController.swift
import UIKit
import InjectStory

class ViewController: UIViewController {
    
    static let viewModelInjection = Injection<AnimalSound>(CatViewModel())
    let viewModel = viewModelInjection.inject()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        soundLabel.text = viewModel.makeSound()
    }

    @IBOutlet weak var soundLabel: UILabel!
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }
}

// CatViewModel.swift
import Foundation

protocol AnimalSound {
    func makeSound() -> String
}

class CatViewModel: AnimalSound {
    func makeSound() -> String{
        return "meow"
    }
}

//  ViewControllerTests.swift

import XCTest
@testable import YourApp

class ViewControllerTests: XCTestCase {
    func testIfViewControllerCallsMeowMethod() {
        //given
        let spy = AnimalSoundSpy()
        //override value returned by viewModelInjection
        ViewController.viewModelInjection.overrideOnce = { spy }
        //create system under test
        let storyboard = UIStoryboard(name: "Main", bundle: nil)
        let sut = storyboard.instantiateViewController(withIdentifier: "viewController") as! ViewController

        //when
        _ = sut.view //to call viewDidLoad
        
        //then
        XCTAssertTrue(spy.makeSoundCalled)
    }
}

//mock class
class AnimalSoundSpy: AnimalSound {
    var makeSoundCalled = false
    func makeSound() -> String{
        makeSoundCalled = true
        return ""
    }
}