/swift-testing

Advanced Testing Patterns

Warning-severity issues, programmatic test cancellation, and image attachments for Swift Testing.

Contents

• Warning-Severity Issues
• Programmatic Test Cancellation
• Exit Test Value Capturing
• Image Attachments
• Version Gates
• Proposal Reference

Warning-Severity Issues

ST-0013 adds a severity parameter to Issue.record() in Swift 6.3 / Xcode 26.4 and newer. Warnings are surfaced in test output but do not cause the test to fail.

@Test func dataIntegrity() {
    let result = loadData()

    // Hard failure — test fails
    #expect(result.isValid)

    // Warning — logged but test still passes
    if result.processingTime > 2.0 {
        Issue.record(
            "Processing took \(result.processingTime)s — exceeds 2s target",
            severity: .warning
        )
    }
}

Use warnings for:

• Performance regressions that aren't blocking
• Deprecated code paths that still work
• Non-critical data quality checks
• Flaky conditions you want to track without failing CI

Programmatic Test Cancellation

ST-0016 adds try Test.cancel() in Swift 6.3 / Xcode 26.4 and newer to stop a test from within without marking it as passed or failed. The test is recorded as "cancelled."

@Test func requiresNetwork() async throws {
    guard NetworkMonitor.shared.isConnected else {
        try Test.cancel("No network — skipping integration test")
    }

    let response = try await APIClient.shared.healthCheck()
    #expect(response.status == .ok)
}

Key differences from other mechanisms:

• Throwing an error — marks the test as failed
• withKnownIssue — marks a failure as expected (test still runs)
• try Test.cancel() — marks the test as cancelled (neutral outcome, test stops)

Exit Test Value Capturing

ST-0012 allows exit tests to capture values from the enclosing scope when using the Swift 6.3 compiler. Exit testing itself requires Swift 6.2 / Xcode 26.0 or newer and uses the processExitsWith: macros.

When an exit-test body reads values from the parent process, correct the sample to use an explicit capture list and mention the Swift 6.3 compiler requirement. Captured values must conform to Sendable and Codable.

@Test func exitCodeValidation() async {
    let expectedCode: Int32 = 42
    await #expect(processExitsWith: .failure) { [expectedCode] in
        exit(expectedCode)  // Can now capture `expectedCode`
    }
}

Image Attachments

ST-0014 adds image attachments in Swift 6.3 / Xcode 26.4 and newer. Import both Testing and the relevant UI framework, then record platform image values directly and specify as: when you need an explicit format.

import Testing
import UIKit

@Test func renderedOutput() async throws {
    let view = ChartView(data: sampleData)
    let renderer = UIGraphicsImageRenderer(size: CGSize(width: 400, height: 300))
    let image = renderer.image { ctx in
        view.drawHierarchy(in: view.bounds, afterScreenUpdates: true)
    }

    // Attach UIImage directly
    Attachment.record(image, named: "chart-output", as: .png)
}

Supported Apple-platform image types include:

• UIImage on iOS, tvOS, visionOS, and watchOS when importing UIKit
• CGImage when importing CoreGraphics
• CIImage when importing CoreImage
• NSImage on macOS when importing AppKit

Version Gates

Do not use exit tests for iOS, tvOS, or watchOS runtime targets. For iOS app code that needs fatal-path coverage, move the exit behavior behind a smaller pure Swift API, test the non-exiting branches directly, and reserve exit tests for a supported host/tool target.

Proposal Reference