SwiftUI Snapshot Testing

A Swift package that provides snapshot testing capabilities for SwiftUI views on both iOS and macOS platforms.

github.com/gabriel/swiftui-snapshot-testing

This package uses github.com/pointfreeco/swift-snapshot-testing with custom extensions for ImageRenderer and fallbacks otherwise.

Usage

Pure SwiftUI Views

import SwiftUISnapshotTesting
import Testing

@Test @MainActor
func testMyViewRender() throws {
    let view = MyView()
    assertRender(view: view, device: .size(400, 400))
}

UIKit-based SwiftUI Views

@Test @MainActor
func testMyViewSnapshot() throws {
    let view = NavigationStack {
        MyView()
    }    
    assertSnapshot(view: view, device: .iOS(width: 400, height: 1000))
}

Async Testing

@Test
func testAsyncTask() async throws {
    let model = await MyViewModel()
    let view = MyView(model: model)
    
    await assertRender(view: view, device: .any)
    try #require(await expression { model.loaded })
    await assertRender(view: view, device: .any)
}

When to Use assertRender vs assertSnapshot

Use assertRender when

• Testing pure SwiftUI views that don't rely on UIKit components
• You want faster test execution (renders directly to images)
• You need cross-platform compatibility (works on both iOS and macOS)

Use assertSnapshot when

• Testing UIKit-based SwiftUI views (like NavigationStack, TabView, etc.)
• You need more accurate rendering that matches the actual app behavior
• Testing complex view hierarchies that may have UIKit dependencies
• You want better debugging capabilities (more detailed error messages)
• Testing views that use UIKit-specific features or integrations

Performance Considerations

• assertRender is generally faster as it renders directly to images
• assertSnapshot may be slower but provides more accurate results for complex views

Device Options

• .size(width, height) - Custom size for any platform
• .iOS(width, height) - iOS-specific device simulation
• .macOS(width, height) - macOS-specific device simulation
• .any - Uses a default size based on platform (e.g. 400x1200 for iOS and 1200x800 for macOS)