Build Status codecov codebeat badge Version Platform CocoaPods Compatible Carthage compatible


LocalServer is a framework that provides various options to create a Swift Local Server, that can independently run on simulators and devices, supporting Xcode Parallel Testing. It’s made in Swift to create Stub Servers, UITest Servers and providing an easy to use Mock capabilities to create Testing doubles (fakes, stubs, spies and mocks). It supports all Apple platform iOS, MacOS, WatchOS and TVOS.


  • [x] Create Stub servers without changing or injecting any of your existing URLSession code;
  • [x] Create Stub versions for WKWebView;
  • [x] Supports Xcode Parallel Testing in simulators and devices;
  • [x] Stub Server for Unit Testing;
  • [x] UITest Stub Server for UI Testing;


Using CocoaPods

Add to your Podfile file

pod 'LocalServer'

Using Carthage

Add to your Cartfile or Cartfile.private file

github "db-in/LocalServer"

Using Swift Package Manager

Add to your Package.swift file

let package = Package(
    name: "myproject",
    dependencies: [
        .package(url: "https://github.com/db-in/LocalServer"),
    targets: [
            name: "myproject",
            dependencies: ["LocalServer"]),

Programming Guide

The features provided are:

  • Stub Server
  • UITest Server

Stub Server

The Stub Server is the base for the Local Server. It can intercept any network call made with the URLSession.

Stub Server

import LocalServer

func startMyLocalServer() {
    let server = StubServer()

    server.route([.GET], url: "https://apple.com") { (request, parameters) -> StubResponse in
        return StubResponse().withStatusCode(204)

    server.route([.POST], url: "https://apple.com") { _,_ in
        return StubResponse().withStatusCode(206)

    StubServer.instance = server

Once the StubServer.instance is defined as non-nil, it will spin the Local Server. To stop the Local Server just set it back to nil, which is the default value.

UITest Server

As per Apple design, the UITest target runs on a separated application, which means it can’t have access to the code in the main application or perform any programaticaly action. The UITest Server used the ProcessInfo bridge to send data from the UITest target to the main application on every launch.

As per Testing best practices, every UITest case should restart the main Application.

UITest Server

Project Structure

// UITest Target
 |-- LocalServer
 |-- JsonFile1.json
 |-- JsonFile2.json
 |-- JsonFile2.json

// Main Target
 |-- LocalServer

Required Code

// UITest Target
    .send(to: "google.com")

// Main Target


Can I ship LocalServer to production (App Store)?

  • Yes, absolutely. The main goal is to provide Mock and Stub capabilities, but nothing stops you to use it in production if required.

If I’m only using it for Debug purpose, shall I use #if DEBUG?

  • As a dynamic Swift framework, LocalServer will only be loaded in runtime at the moment it’s first called. So if your production code never makes use of any LocalServer API, it will not even be loaded. #if DEBUG can be used, but as per UITest Standards, you can also consider the usage of something like XCUIApplication().launchArguments + if ProcessInfo().arguments.contains("-UITests") { ... }
  • UI Testing Quick Guide/
  • Getting Started With Xcode UI Testing In Swift