Testing with XCTest

Testing with XCTest

Write unit tests to verify logic and UI tests to automate end-to-end flows using the XCTest framework.

Unit Tests

Create a tests target in Xcode and add test cases that extend XCTestCase.

Syntax: class MyTests: XCTestCase { func testSomething() { XCTAssertEqual(...) } }

import Foundation

struct Math {
  static func add(_ a: Int, _ b: Int) -> Int { a + b }
}

import XCTest
@testable import MyApp

final class MyTests: XCTestCase {
  func testAdd() {
    XCTAssertEqual(Math.add(2, 3), 5)
  }
}

This example defines a pure function and a unit test verifying the result with XCTAssertEqual.

Test Target Setup

• Add a Unit Testing Bundle target in Xcode (File → New → Target).
• Keep test files under the tests target; import your app with @testable import when needed.
• Use Target Membership to choose whether a file belongs to the app or tests.

Writing Tests (AAA)

Arrange your inputs, Act by calling the code under test, Assert on the result.

import XCTest
@testable import MyApp

final class MyTests: XCTestCase {
  func testAdd() {
    // Arrange
    let a = 2, b = 3
    // Act
    let sum = Math.add(a, b)
    // Assert
    XCTAssertEqual(sum, 5)
  }
}

XCTAssert Variants

Assert on conditions and values.

• XCTAssertEqual, XCTAssertNotEqual
• XCTAssertTrue, XCTAssertFalse
• XCTAssertNil, XCTAssertNotNil
• XCTAssertThrowsError, XCTAssertNoThrow

Async Tests

Wait for asynchronous work to complete.

import XCTest

final class AsyncTests: XCTestCase {
  func testExpectation() {
    let exp = expectation(description: "async work")
    DispatchQueue.global().async {
      // simulate work
      exp.fulfill()
    }
    wait(for: [exp], timeout: 1.0)
  }
}

Performance Tests

Measure execution time and memory usage.

import XCTest

final class PerformanceTests: XCTestCase {
  func testSortPerformance() {
    let input = Array(0..<10_000).shuffled()
    measure {
      _ = input.sorted()
    }
  }
}

Test Plans & CI

Organize configurations (schemes, destinations, diagnostics) and run tests in CI with xcodebuild test targeting a simulator device.

• Use Test Plans to organize configurations (schemes, destinations, diagnostics).
• Run tests in CI with xcodebuild test targeting a simulator device.
• Prefer deterministic tests; mock network and time; parallelize where possible.

UI Tests

Use XCUIApplication to launch the app and interact with UI elements by accessibility.

Syntax:

• let app = XCUIApplication(); app.launch()
• query elements with app.buttons["Label"]
• assert with XCTAssertTrue(...)

import SwiftUI

struct CounterView: View {
  @State private var count = 0
  var body: some View {
    VStack(spacing: 12) {
      Text("Count: \(count)")
      Button("Increment") { count += 1 }
    }
    .padding()
  }
}

import SwiftUI

struct ContentView: View {
  var body: some View { CounterView() }
}

import SwiftUI

@main
struct MyApp: App {
  var body: some Scene {
    WindowGroup { ContentView() }
  }
}

import XCTest

final class MyUITests: XCTestCase {
  func testIncrementButtonIncrementsCount() {
    let app = XCUIApplication()
    app.launch()

    let increment = app.buttons["Increment"]
    XCTAssertTrue(increment.exists)
    increment.tap()

    XCTAssertTrue(app.staticTexts["Count: 1"].exists)
  }
}

This example launches the app, taps a button, and verifies that a label exists.