Swinject & XCode UI Tests

[sialcasa]

Is there a best practice to change the Container configuration in a XCode UI Test, to mock for example a RestClient-Class that implements a Protocol that I could mock?

[thalmicMark]

What I do is I pass a launch argument to the app in my UI test target. In my app's AppDelegate, I process this argument from ProcessInfo.processInfo.arguments.

If I find my UITest argument, I apply a special UI test assembly to my assembler which overrides all of the registries I'd like to mock out for UI tests. I also make sure to apply the test assembly after all my main assemblies are applied.

[yoichitgy]

Thanks @thalmicMark for the nice practice. I've never tried Swinject with Xcode UI Test. @thalmicMark's practice is the best practice as far as I know. @sialcasa, did it fit in your case?

[yoichitgy]

Please feel free to reopen this issue if the practice didn't fit in your case.

[SuperTango]

@thalmicMark can you provide an example of how this works for you? i'm embarking on a simliar ui test journey.

[thalmicMark]

Sure thing. I've got a MainAssembler class where I apply all my Assemblies in the constructor. The MainAssembler class is instantiated by my AppDelegate.

class MainAssembler {
    let assembler: Assembler

    init() {
        assembler = Assembler(container: SwinjectStoryboard.defaultContainer)
        assembler.apply(assemblies: MyAssemblies.assemblies)

        // Apply UITest Assemblies after applying regular assemblies to achieve overwriting of 
        // registrations.
        let processInfo = ProcessInfo.processInfo
        if processInfo.arguments.contains("UITests") {
            assembler.apply(assemblies: UITestAssemblies.assemblies)
        }
    }
}

// I use non-instantiatable structs to achieve namespacing.
struct UITestAssemblies {
    // Static property to hold all my assemblies for organizational purposes.
    static let assemblies: [AssemblyType] = [...]

    private init() { }
}

@UIApplicationMain
class AppDelegate: UIResponder {
    let mainAssembler = MainAssembler()
}

Then, in my UI Tests, I set the launch argument:

class MyUITest: XCTestCase {
    let app = XCUIApplication()

    override func setUp() {
        super.setUp()

        continueAfterFailure = false

        app.launchArguments.append("UITests")
        app.launch()
    }
}

You can organize your Assemblies however you want, but the main point is to use the launch argument to trigger your UITest assemblies to override certain registrations when performing UITests.