snapshotino

A lightweight, low-barrier-to-entry snapshot testing library for iOS

Why snapshot tests?

• They’re easy to write, maintain, and debug
• They focus on the visual output of your code (which is what the user sees)
• They encourage you to write small, modular, and testable components

What this library is capable of

• Recording and comparing snapshots of SwiftUI.View, UIView, and UIViewController
• Storing the expected and actual snapshots in the test results

That’s it!

What it’s definitely not capable of

• Recording snapshots using different accessibility traits or devices

What it’s probably not capable of

• Any other use cases that weren’t mentioned above

Author’s note

If you are looking for a library that you will use on your production app, you should probably consider more powerful tools like pointfreeco/swift-snapshot-testing or uber/ios-snapshot-test-case. This library is more of a pet project than a finished product. I wanted to snapshot-test the small apps and components I build for fun without importing a full-blown 3rd party for my limited use case.

As a less interesting fact, this is also why I tried to imply the small size of the initiative in the project name, by using the -ino suffix, which appears to be a common diminutive suffix in Italian.

How to use

• Add the library as a dependency using Swift Package Manager
• Import snapshotino in your XCTestCase implementation
• Use assertSnapshot to record and compare snapshots, examples below

For recording snapshots

Simply call assertSnapshot by setting record to true. The test will fail but the snapshot will be recorded under the __snapshots__ folder next to the test file.

func testUIViewController() throws {
    try assertSnapshot(of: SampleViewController(), record: true)
}

For asserting snapshots

Call assertSnapshot without setting the record attribute (it’s false by default).

func testUIViewController() throws {
    try assertSnapshot(of: SampleViewController())
}

func testUIView() throws {
    if let view = Bundle.main.loadNibNamed("SampleView", owner: self, options: nil)?.first as? SampleView {
        try assertSnapshot(of: view)
    }
}

func testView() throws {
    let view = ContentView(viewModel: .init(imageName: "circle", text: "test"))
    try assertSnapshot(of: view.asSnapshottableView)
}

Note that SwiftUI.View cannot be used directly because it’s not a concrete type. We use the asSnapshottableView property instead, which will return a wrapper type that can be passed to assertSnapshot.

Sample project

https://github.com/kublaios/KleinSnapshotTesting

License

This project is released under the MIT license. See LICENSE for details.