ViewInspector 🕵️‍♂️ for SwiftUI

ViewInspector is a library for unit testing SwiftUI views. It allows for traversing a view hierarchy at runtime providing direct access to the underlying View structs.

Why?

SwiftUI view is a function of state. We could provide it with the input but could not verify the output... Until now!

Helpful links

• Inspection guide
• SwiftUI API coverage

Use cases

1. Search the view of a specific type or condition

Use one of the find functions to quickly locate a specific view or assert there are none of such:

try sut.inspect().find(button: "Back")

try sut.inspect().findAll(ViewType.Text.self,
                          where: { try $0.attributes().isBold() })

Check out this section in the guide for the reference.

2. Read the inner state of the standard views

Standard SwiftUI views are no longer a black box:

let sut = Text("Completed by \(72.51, specifier: "%.1f")%").font(.caption)

let string = try sut.inspect().text().string(locale: Locale(identifier: "es"))
XCTAssertEqual(string, "Completado por 72,5%")

XCTAssertEqual(try sut.inspect().text().attributes().font(), .caption)

Each view has its own set of inspectable parameters, you can refer to the API coverage document to see what's available for a particular SwiftUI view.

3. Verify your custom view's state

Obtain a copy of your custom view with actual state and references from the hierarchy of any depth:

let sut = try view.inspect().find(CustomView.self).actualView()
XCTAssertTrue(sut.viewModel.isUserLoggedIn)

The library can operate with various types of the view's state, such as @Binding, @State, @ObservedObject and @EnvironmentObject.

4. Trigger side effects

You can simulate user interaction by programmatically triggering system-control callbacks:

try sut.inspect().find(button: "Close").tap()

let list = try view.inspect().list()
try list[5].view(RowItemView.self).callOnAppear()

The library provides helpers for writing asynchronous tests for views with callbacks.

FAQs

Which views and modifiers are supported?

Check out the API coverage.

Is it using private APIs?

ViewInspector is using the official Swift reflection API to dissect the view structures. So it'll be production-friendly even if you could somehow ship the test target to the production.

How do I add it to my Xcode project?

Assure you're adding the framework to your unit-test target. Do NOT add it to the main build target.

Swift Package Manager

https://github.com/nalexn/ViewInspector

Carthage

github "nalexn/ViewInspector"

CocoaPods

pod 'ViewInspector'

How do I use it in my project?

Please refer to the Inspection guide. You can also check out my other project that harnesses the ViewInspector for testing the entire UI.

Contributions

Contributions are welcomed! If you see an unsupported view or modifier, you can either open an issue (so I could prioritize such SwiftUI APIs over the rest), or try to crack it yourself: use the print("\(Inspector.print(<#view#>) as AnyObject)") as the starting point of the investigation.