Mismatch in Generated Images on iOS 18 vs. Previous Versions

[kyyoussef]

Describe the bug

• The assertSnapshots method is producing different images for the same view compared to earlier iOS versions. After upgrading my testing devices to iOS 18, my test cases have started to fail.

To Reproduce

struct ContentView: View {
    var body: some View {
        HStack {
            VStack {
                Text("Hello")
                Text("Hello, world!")
                HStack {
                    Text("Hello, world!")
                    Text("Hello, world!")
                }
                HStack {
                    Text("Hello, world!")
                    Text("Hello, world!")
                    Text("Hello, world!")

                }
                Text("Hello, world!")
                Text("Hello, world!")

            }
            .padding()
        }
    }
}

// testing method 
    func testUI() throws {
    
// method is pass either on iOS 18 or 17  (depending on the record on the disk)
        assertSnapshots(of: ContentView(), as: ["": .wait(for: 1,
                                                          on: .image(precision: 1,
                                                                     layout: .fixed(width: 375, height: 667)))])
    }

Expected behavior

• consistent image generated.

Environment

• swift-snapshot-testing version [e.g. 1.9.0]
• Xcode Version 15.3
• Swift [e.g. 5.5]
• OS: iOS 18 and iOS 17

[mbrandonw]

Hi @kyyoussef, this is to be expected. iOS updates can cause small changes in how views are laid out. You really have no choice but to re-record all of your images.

Since this isn't an issue with the library I am going to convert it to a discussion. Please feel free to continue the conversation over there!

[kyyoussef]

@mbrandonw Thank you, is there any way to decouple my tests from the os version ?

[Rion-Kaneshiro]

@mbrandonw Wouldn't that be a feature request? Especially now with the big changes with iOS 26 and supporting multiple OS-Versions that will be vastly different going forward.

In a client project I also face the situation, that we run the test on iOS 17, 18 and 26.

As of now this is not possible with Snapshot Testing, unfortunately.