I am writing test for my project and declared a remote API client protolcol:
public protocol ApiClient {
func load(completion: #escaping ([Any]?, String?))
}
and defined a moc api client that confirms to ApiClient:
class MocApiClient: ApiClient {
func loadFlights(completion: #escaping ([Any]?, String?)) {
// Load a sample JSON file and return it as response
}
}
this way I am able return a response by loading a JSON file. This is the happy path of the test. After it I started to think about testing different possible response types and decided that I should be able to alter behaviour of the MocApiClient and defined this:
enum TestPath {
case success
case failure
}
and using it with MocApiClient:
class MocApiClient: ApiClient {
var path: TestPath = .success
func load(completion: #escaping ([Any]?, String?) -> Void) {
switch path {
case .success:
completion([...], nil)
case .failure:
completion(nil, "error message")
}
}
}
Doyu think this is a good solution?
Do you have any beter approachs?
Your approach seems fine if you have just a few simple tests.
However, if you have a relatively complex logic and need to test many positive and negative paths, an alternative to your solution would be creating several different mocking objects, each one having a single purpose.
That way, you'll avoid a massive all-purpose mocking object problem and also will be able to define your mocking objects right inside the tests methods that use them, thus making your tests even more focused and independent.
Something like this:
func testSuccessfulResponse() {
class MockApiClientSuccessfulResponse: ApiClient {
...
}
...
}
func testMalformedResponse() {
class MockApiClientMalformedResponse: ApiClient {
...
}
...
}
func testInconsistentData() {
class MockApiClientInconsistentData: ApiClient {
...
}
...
}
Hope this helps and happy unit testing!
Related
I am trying to migrate some code using a Repository pattern from Vapor 3 to Vapor 4. I have gone through the documentation of this specific pattern from the Vapor 4 documentation, and I think I understand it for the most part.
The one thing I am not getting, however, is the way that the repository factory gets set within the Application extension. The example from the documentation shows this:
extension Application {
private struct UserRepositoryKey: StorageKey {
typealias Value = UserRepositoryFactory
}
var users: UserRepositoryFactory {
get {
self.storage[UserRepositoryKey.self] ?? .init()
}
set {
self.storage[UserRepositoryKey.self] = newValue
}
}
}
If I am reading the getter method correctly (and I might not be - I'm far from a Swift expert), a new instance of the UserRepositoryFactory structure will be created and returned when app.users is referenced. At that time, however, it does not appear that the contents of self.storage[UserRepositoryKey.self] is changed in any way. So if I happened to access app.users two times in a row, I would get 2 different instances returned to me and self.storage[UserRepositoryKey.self] would remain set to nil.
Following through the rest of the sample code in the document, it appears to define the make function that will be used by the factory when configuring the app as so:
app.users.use { req in
DatabaseUserRepository(database: req.db)
}
Here it seems like app.users.use would get a new factory instance and call its use function to set the appropriate make method for that instance.
Later, when I go to handle a request, I use the request.users method that was defined by this Request extension:
extension Request {
var users: UserRepository {
self.application.users.make!(self)
}
}
Here it seems like self.application.users.make would be invoked on a different repository factory instance that is referenced by self.application.users. It would therefore not apply the factory's make method that was set earlier when configuring the application.
So what am I missing here?
It looks like the docs are slightly out of date for that. You can have a look at how views or client is done, but somewhere you need to call initialize() to set the repository. Here's what my working repository looks like:
import Vapor
extension Application {
struct Repositories {
struct Provider {
let run: (Application) -> ()
public init(_ run: #escaping (Application) -> ()) {
self.run = run
}
}
final class Storage {
var makeRepository: ((Application) -> APIRepository)?
init() { }
}
struct Key: StorageKey {
typealias Value = Storage
}
let application: Application
var repository: APIRepository {
guard let makeRepository = self.storage.makeRepository else {
fatalError("No repository configured. Configure with app.repositories.use(...)")
}
return makeRepository(self.application)
}
func use(_ provider: Provider) {
provider.run(self.application)
}
func use(_ makeRepository: #escaping (Application) -> APIRepository) {
self.storage.makeRepository = makeRepository
}
func initialize() {
self.application.storage[Key.self] = .init()
}
private var storage: Storage {
if self.application.storage[Key.self] == nil {
self.initialize()
}
return self.application.storage[Key.self]!
}
}
var repositories: Repositories {
.init(application: self)
}
}
That autoinitializes itself the first time it's used. Note that APIRepository is the protocol used for my repostiory. FluentRepository is the Fluent implementation of that protocol. Then like you I have an extension on Request to use it in request handlers:
extension Request {
var repository: APIRepository {
self.application.repositories.repository.for(self)
}
}
Finally, you need to configure it to use the right repository. So in my configure.swift I have:
app.repositories.use { application in
FluentRepository(database: application.db)
}
and in tests I can switch it for the in-memory repository that doesn't touch the DB:
application.repositories.use { _ in
return inMemoryRepository
}
I have managed to get the example from the docs working as-is.
Tracing through the execution with the debugger, there is the predictable call to get, as you say, and this returns the instance from .init() as the failover from not having a previously stored value. Included in the example you refer to is:
struct UserRepositoryFactory {
var make: ((Request) -> UserRepository)?
mutating func use(_ make: #escaping ((Request) -> UserRepository)) {
self.make = make
}
}
This use function is executed next, which is mutating and updates the variable make. I believe it is this change to make that then triggers a call to set. It certainly happens immediately after use and before execution moves on in configure.swift. So, by the time the server formally starts and you actually use the Repository in a route, there is a stored instance that is reused as required.
I am working in an iOS application called ConnectApp and I am using a framework called Connector. Now, Connector framework completes actual connection task with BLE devices and let my caller app (i.e. ConnectApp) know the connection request results through ConnectionDelegate. Let's see example code,
ConnectApp - host app
class ConnectionService: ConnectionDelegate {
func connect(){
var connector = Connector()
connector.setDelegate(self)
connector.connect()
}
func onConnected(result: ConnectionResult) {
//connection result
}
}
Connector Framework
public class ConnectionResult {
// many complicated custom variables
}
public protocol ConnectionDelegate {
func onConnected(result: ConnectionResult)
}
public class Connector {
var delegate: ConnectionDelegate?
func setDelegate(delegate: ConnectionDelegate) {
self.delegate = delegate
}
func connect() {
//…..
// result = prepared from framework
delegate?.onConnected(result)
}
}
Problem
Sometimes developers have no BLE device and we need to mock the Connector layer of framework. In case of simple classes (i.e. with simpler methods) we could have used inheritance and mock the Connector with a MockConnector which might override the lower tasks and return status from MockConnector class. But when I need to deal with a ConnectionDelegate which returns complicated object. How can I resolve this issue?
Note that framework does not provide interfaces of the classes rather we need to find way around for concrete objects like, Connector, ConnectionDelegate etc.
Update 1:
Trying to apply Skwiggs's answer so I created protocol like,
protocol ConnectorProtocol: Connector {
associatedType MockResult: ConnectionResult
}
And then injecting real/mock using strategy pattern like,
class ConnectionService: ConnectionDelegate {
var connector: ConnectorProtocol? // Getting compiler error
init(conn: ConnectorProtocol){
connector = conn
}
func connect(){
connector.setDelegate(self)
connector.connect()
}
func onConnected(result: ConnectionResult) {
//connection result
}
}
Now I am getting compiler error,
Protocol 'ConnectorProtocol' can only be used as a generic constraint because it has Self or associated type requirements
What am I doing wrong?
In Swift, the cleanest way to create a Seam (a separation that allows us to substitute different implementations) is to define a protocol. This requires changing the production code to talk to the protocol, instead of a hard-coded dependency like Connector().
First, create the protocol. Swift lets us attach new protocols to existing types.
protocol ConnectorProtocol {}
extension Connector: ConnectorProtocol {}
This defines a protocol, initially empty. And it says that Connector conforms to this protocol.
What belongs in the protocol? You can discover this by changing the type of var connector from the implicit Connector to an explicit ConnectorProtocol:
var connector: ConnectorProtocol = Connector()
Xcode will complain about unknown methods. Satisfy it by copying the signature of each method it needs into the protocol. Judging from your code sample, it may be:
protocol ConnectorProtocol {
func setDelegate(delegate: ConnectionDelegate)
func connect()
}
Because Connector already implements these methods, the protocol extension is satisfied.
Next, we need a way for the production code to use Connector, but for test code to substitute a different implementation of the protocol. Since ConnectionService creates a new instance when connect() is called, we can use a closure as a simple Factory Method. The production code can supply a default closure (creating a Connector) like with a closure property:
private let makeConnector: () -> ConnectorProtocol
Set its value by passing an argument to the initializer. The initializer can specify a default value, so that it makes a real Connector unless told otherwise:
init(makeConnector: (() -> ConnectorProtocol) = { Connector() }) {
self.makeConnector = makeConnector
super.init()
}
In connect(), call makeConnector() instead of Connector(). Since we don't have unit tests for this change, do a manual test to confirm we didn't break anything.
Now our Seam is in place, so we can begin writing tests. There are two types of tests to write:
Are we calling Connector correctly?
What happens when the delegate method is called?
Let's make a Mock Object to check the first part. It's important that we call setDelegate(delegate:) before calling connect(), so let's have the mock record all calls in an array. The array gives us a way to check the call order. Instead of having the test code examine the array of calls (acting as a Test Spy which just records stuff), your test will be cleaner if we make this a full-fledged Mock Object — meaning it will do its own verification.
final class MockConnector: ConnectorProtocol {
private enum Methods {
case setDelegate(ConnectionDelegate)
case connect
}
private var calls: [Methods] = []
func setDelegate(delegate: ConnectionDelegate) {
calls.append(.setDelegate(delegate))
}
func connect() {
calls.append(.connect)
}
func verifySetDelegateThenConnect(
expectedDelegate: ConnectionDelegate,
file: StaticString = #file,
line: UInt = #line
) {
if calls.count != 2 {
fail(file: file, line: line)
return
}
guard case let .setDelegate(delegate) = calls[0] else {
fail(file: file, line: line)
return
}
guard case .connect = calls[1] else {
fail(file: file, line: line)
return
}
if expectedDelegate !== delegate {
XCTFail(
"Expected setDelegate(delegate:) with \(expectedDelegate), but was \(delegate)",
file: file,
line: line
)
}
}
private func fail(file: StaticString, line: UInt) {
XCTFail("Expected setDelegate(delegate:) followed by connect(), but was \(calls)", file: file, line: line)
}
}
(That business with passing around file and line? This makes it so that any test failure will report the line that calls verifySetDelegateThenConnect(expectedDelegate:), instead of the line that calls XCTFail(_).)
Here's how you'd use this in ConnectionServiceTests:
func test_connect_shouldMakeConnectorSettingSelfAsDelegateThenConnecting() {
let mockConnector = MockConnector()
let service = ConnectionService(makeConnector: { mockConnector })
service.connect()
mockConnector.verifySetDelegateThenConnect(expectedDelegate: service)
}
That takes care of the first type of test. For the second type, there's no need to test that Connector calls the delegate. You know it does, and it's outside your control. Instead, write a test to call the delegate method directly. (You'll still want it to make a MockConnector to prevent any calls to the real Connector).
func test_onConnected_withCertainResult_shouldDoSomething() {
let service = ConnectionService(makeConnector: { MockConnector() })
let result = ConnectionResult(…) // Whatever you need
service.onConnected(result: result)
// Whatever you want to verify
}
You could try
protocol MockConnector: Connector {
associatedType MockResult: ConnectionResult
}
Then, for each connector you need to mock, define a concrete class that conforms to this mock connector
class SomeMockConnector: MockConnector {
struct MockResult: ConnectionResult {
// Any mocked variables for this connection result here
}
// implement any further requirements from the Connector class
var delegate: ConnectionDelegate?
func connect() {
// initialise your mock result with any specific data
let mockResult = MockResult()
delegate?.onConnected(mockResult)
}
}
Is there any way to close Internet Connection for Unit Test? I have to check async function when the device on online or not. How can I do that ?
I know the Additional tools Package but I want to write this feature with programmatically.
Thanks in Advance
This is how I mock an API call. The steps requires
1) No internet connection
2) Mocking the API Call and data
I have created data models for the api response and this is how I am mocking it
func buildActivityList() -> ActivityResponse {
let resp = ActivityResponse(json: .null)
let userHistory = ActivityUserHistory(json: .null)
userHistory.time = "2018-02-16T07:41:54.046Z"
resp.userHistory = [userHistory]
//Add all other relevant data
return resp
}
Next you need to override the function were you are calling API and pass the above mocked data as API response.
Suppose you have a class where you call the api
class UserService {
func getUserDetails(completion: (_: ActivityResponse?, _: Error?)) {
//get RESPONSE from server
let data = ActivityResponse(object: RESPONSE)
return completion(data, nil)
}
}
Now in your test class call the buildActivityList() which we created and pass it in the mock class.
class MockUserService: UserService {
override func getUserDetails(completion: (_: ActivityResponse?, _: Error?)) {
return completion(buildActivityList(), nil)
}
}
This way whenever you test an API call, the mock data will be injected. Thus no need for internet connection.
Hope this helps
I know this looks like a common question but after reading 10-15 tutorial and looking how can I write test for my service class. I can't solve moving static functions to protocol or etc.. for dependency injection
I have a network layer like below image. All my function classes (like fetch users, news, media etc..) calls "Service Caller" class and after that If response is error; calls "Service Error" class to handle error and If not error, decode the JSON.
My problem is that I'm calling service class as a static function like "ServiceCaller.performRequest" and If It gets error I'm also calling error class as static like "ServiceError.handle". Also It calls URLCache class to get path of request url. I'm not sure how can I make them dependency inject and mock in test class. As I find in tutorials, I should write it like;
protocol MyProtocol{
func myfunction() -> Void
}
class A{
let testProtocol = MyProtocol!
init(pro: MyProtocol){
testProtocol = pro
}
}
and in setup function in test class it probably;
myMockProtocol = ...
myTestclass = A.init(pro: myMockProtocol)
but I can't find how can I get ride of static calls like ServiceCaller.performRequest or ServiceError.handle..; (Simplified version in the bottom part of question)
class AppInitService{
static func initAppRequest(_ completion: #escaping (_ appInitRecevingModel: Result<AppInitRecevingModel>) -> Void) {
let sendingModel = AppInitSendingModel(cmsVersion: AppDefaults.instance.getCMSVersion())
let route = ServiceRouter(method: .post, path: URLCache.instance.getServiceURL(key: URLKeys.initApp), parameters: (sendingModel.getJSONData()), timeoutSec: 1)
ServiceCaller.performRequest(route: route) { (result) in
if let error = result.error{
if let statusCode = result.response?.statusCode{
completion(.error(ServiceError.handle(error: error, statusCode: statusCode)))
}else{
completion(.error(ServiceError.handle(error: error, statusCode: error._code)))
}
}else{
if let data = result.data{
do{
var responseJson = JSON(data)
responseJson["idleTimeoutInMinutes"] = 10
let input = try AppInitRecevingModel(data: responseJson.rawData())
completion(.success(input))
}catch let error{
completion(.error(ServiceError.handle(error: error, statusCode: -1002)))
}
}
}}
}
}
My Test class:
class MyProjectAppInitTests: XCTestCase {
var appInitTest: AppInitService!
override func setUp() {
super.setUp()
// Put setup code here. This method is called before the invocation of each test method in the class.
appInitTest = AppInitService.init()
}
override func tearDown() {
// Put teardown code here. This method is called after the invocation of each test method in the class.
appInitTest = nil
super.tearDown()
}
func testExample() {
// This is an example of a functional test case.
// Use XCTAssert and related functions to verify your tests produce the correct results.
let testParamater = ["string":"test"]
let route = ServiceRouter(method: .post, path: "/testPath", parameters: testParamater.getJSONData(), timeoutSec: 10)
appInitTest. //cant call anything in here
}
Tutorials I looked for Unit Test;
https://www.raywenderlich.com/150073/ios-unit-testing-and-ui-testing-tutorial
https://www.swiftbysundell.com/posts/time-traveling-in-swift-unit-tests
https://marcosantadev.com/test-doubles-swift
http://merowing.info/2017/04/using-protocol-compositon-for-dependency-injection/
EDIT: One solution maybe writing init class for whole network layer and service classes then get rid of static functions? But I'm not sure If It will be a good approach.
EDIT 2: Simplified Code;
class A{
static func b(completion:...){
let paramater = ObjectModel(somevariable: SomeClass.Singleton.getVariable()) //Data that I sent on network request
let router = ServiceRouter(somevariable: SomeClassAgain.Singleton.getsomething()) //Router class which gets parameters, http method etc..
NetworkClass.performNetworkRequest(sender: object2){ (result) in
//Result - What I want to test (Write UnitTest about)
}
}
}
Use mocking.
class ServiceCallerMock: ServiceCaller {
override class func performRequest(route: ServiceRouter) -> (Any?) -> Void? {
//your implementation goes here
}
}
You could mock ServiceCaller and override the performRequest method, then change the function to:
static func initAppRequest(_ completion: #escaping (_ appInitRecevingModel: Result<AppInitRecevingModel>) -> Void, serviceCaller: ServiceCaller.Type = ServiceCaller.self) {
...
serviceCaller.performRequest(route: route) { (result) in
...
}
Then you could call the initAppRequest function using your mock implementation of ServiceCaller.
New to IOS programming but just wondering where is the best place to put functions that I would use throughout my code. For example, I want to write a few functions to perform a POST request to a web service and return a dictionary. Maybe another function to do some calculations. Is it best to create another .swift file and put all my functions there. And what would be a good name to give the file if so?
public func postRequest() -> [String:String] {
// do a post request and return post data
return ["someData" : "someData"]
}
The best way is to create a helper class with static functions, like this:
class Helper{
static func postRequest() -> [String:String] {
// do a post request and return post data
return ["someData" : "someData"]
}
}
Now every time you need to use postRequest you can just use like so: Helper.postRequest()
I usually create a separate class if I have functions that will be used by multiple classes, especially for the ones involving network operations.
If you just have separate functions that will be used, you can simply create static functions inside that class so it is easily accessible by other classes in a static way:
class DataController {
static func getData() -> [String:String] {
// do some operations
return ["someData" : "someData"]
}
}
let data = DataController.getData() // example
However, what often has been the case for me (especially if it involves more complicated operations) was that these network operations needed to establish an initial connection beforehand or required some initial setups, and they also performed asynchronous operations that needed to be controlled. If this is the case and you will often be calling such methods, you might want to create a singleton object that you could use throughout different classes and functions. This way, you could do the initial setup or establish an initial connection just once, and then do the rest as needed with the other functions, instead of doing them every time the function gets called.
Creating a singleton object is pretty simple in Swift:
class DataController {
static let sharedInstance = DataController() // singleton object
init() {
// do initial setup or establish an initial connection
}
func getData() -> [String:String] {
// do some operations
return ["someData" : "someData"]
}
}
let data = DataController.sharedInstance.getData() // example
For the name of the class, I usually name it something like DataController or DataHelper, but anything that makes sense as a "helper" class would work.
Hope this helps :)
For reusable functions it depends what I decide to use. For this specific case I use a separate file, because posting to a backend will become more complicated when the application evolves. In my app I use a backend class, with all kinds of helper classes:
struct BackendError {
var message : String
}
struct SuccessCall {
var json : JSON
var containsError : Bool {
if let error = json["error"].string {
return true
}
else {
return false
}
}
}
typealias FailureBlock = (BackendError) -> Void
typealias SuccessBlock = (SuccessCall) -> Void
typealias AlamoFireRequest = (path: String, method: Alamofire.Method, data: [String:String]) -> Request
typealias GetFunction = (path: String , data: [String : String], failureBlock: FailureBlock, successBlock: SuccessBlock) -> Void
class Backend {
func getRequestToBackend (token: String )(path: String , data: [String : String], failureBlock: FailureBlock, successBlock:
}
For other cases I often use extensions on Swift classes. Like for getting a random element from an Array.
extension Array {
func sampleItem() -> T {
let index = Int(arc4random_uniform(UInt32(self.count)))
return self[index]
}
}
This very old question but I would like to chirp some more points.
There are a few option, basically you can write your utility functions in Swift -
A class with static function. For example
class CommonUtility {
static func someTask() {
}
}
// uses
CommonUtility.someTask()
Also, you can have class method's as well instead of static method but those functions can be overridden by subclasses unlike static functions.
class CommonUtility {
class func someTask() {
}
}
// uses
CommonUtility.someTask()
Secondly, you can have Global functions as well, that are not part of any class and can be access anywhere from your app just by name.
func someTask() {
}
Though, selecting one over other is very subjective and I thing this is ok to make a class with static function in this particular case, where you need to achieve networking functionality but if you have some functions which perform only one task than Global function is a way to go because Global functions are more modular and separate out single tasks for a single function.
In case of static functions, if we access one of the static member, entire class gets loaded in memory. But in case of global function, only that particular function will be loaded in mem
You can create a separate swift class, might name it WebServicesManager.swift, and write all methods related to web requests in it.
You can use class methods, or singleton pattern to access the methods.