Swift
XCTest includes a built-in performance testing API that lets you measure how long a block of code takes and compare it against a stored baseline. When performance regresses, the test fails — giving you an early warning before slow code ships to users. The measure Block The simplest performance test wraps
Swift
Instruments is Apple's performance analysis tool included with Xcode. It attaches to a running process — including your test target — and records CPU usage, memory allocations, and retain cycles. When tests run slowly or your app leaks memory during a test run, Instruments shows you exactly where the time
iOS
Apple's swift-testing framework (available in Xcode 16, Swift 6) replaces XCTest's 20-year-old Objective-C heritage with a modern, macro-based API. Instead of XCTAssertEqual, you write #expect(a == b). Instead of func testSomething(), you write @Test func something(). Parameterized tests, parallel execution, and expressive failure messages are built
iOS
Running xcodebuild test directly gives you raw XML logs, cryptic failures, and no easy way to integrate results into your CI pipeline. Fastlane's scan action wraps xcodebuild with sensible defaults, human-readable output, JUnit XML for CI consumption, HTML reports, and built-in Slack notifications. This guide covers scheme configuration,
iOS
Realm's object graph persistence is tightly coupled to its runtime — you can't just pass in a mock dictionary. Testing Realm-backed iOS code requires either an in-memory Realm configuration (fast, isolated, no file cleanup) or a purpose-built mock layer. This guide covers both approaches, plus migration testing,
iOS
Combine's asynchronous, declarative model makes testing tricky — pipelines emit values over time, operators transform them, and errors can cancel the stream. This guide covers two approaches: the built-in XCTestExpectation pattern for simple cases, and the CombineExpectations library for ergonomic, readable publisher assertions. You'll write tests for
iOS
XCUITest runs your app in a simulator — it's slow, flaky, and gives no introspection into SwiftUI internals. ViewInspector lets you unit test SwiftUI views directly: inspect the view hierarchy, find subviews by type, trigger bindings, simulate button taps, and assert on text values — all without launching a simulator.
Maestro
Maestro is a mobile testing framework that replaces imperative test code with declarative YAML flows. You describe what the user does — tap this, type that, assert visible — and Maestro handles synchronization, retries, and cross-platform execution. This guide covers the flow syntax, handling dynamic content, CI integration, and how Maestro compares
Appium
Appium 2.x is a significant architectural departure from Appium 1.x — drivers and plugins are now installed separately, the server is leaner, and WebdriverIO has emerged as the best client library for writing and running tests. This guide covers the complete setup for iOS and Android, element locator discovery
Detox
Detox is a gray-box E2E testing framework for React Native that eliminates flakiness by synchronizing with the app's JavaScript thread and native animation system rather than relying on sleep timers. This guide walks through complete iOS and Android setup, the synchronization model that makes Detox reliable, and CI
Testing
Apple Push Notification Service (APNS) has stricter requirements than FCM: a 4096-byte payload limit, two distinct environments (sandbox and production), and a choice between certificate-based and JWT token-based authentication. This guide walks through testing APNS integrations in Python using httpx-based clients, mocked HTTP/2 connections, and payload size assertions — without
Testing
VoiceOver is the primary screen reader on iOS, and testing it manually doesn't scale. XCTest's accessibility audit APIs let you catch labeling gaps, broken focus order, and trait mismatches in CI before they reach real users. This guide covers the full automation stack from XCUIAccessibility queries