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
• Proposal Reference

Warning-Severity Issues

ST-0013 adds a severity parameter to Issue.record(). 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() to stop a test from within without marking it as passed or failed. The test is recorded as "cancelled."

@Test func requiresNetwork() 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. Previously, #expect(exitsWith:) closures could not reference local variables.

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

Image Attachments

ST-0014 adds cross-import overlays for attaching images to test results. When you import both Testing and a UI framework, attachment initializers for platform image types become available.

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 — available via cross-import overlay
    Attachment(image, named: "chart-output").record()
}

Supported types via overlays:

• UIImage (when importing UIKit)
• CGImage (when importing CoreGraphics)
• NSImage (when importing AppKit — macOS)

Proposal Reference