Testing with XCTest

Unit Tests

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

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

Example

Demo.swift

MyTests.swift

import Foundation

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

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

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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.

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Writing Tests (AAA)

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

Example

MyTests.swift

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)
  }
}

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XCTAssert Variants

Assert on conditions and values.

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

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Async Tests

Wait for asynchronous work to complete.

Example

AsyncTests.swift

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)
  }
}

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Performance Tests

Measure execution time and memory usage.

Example

PerformanceTests.swift

import XCTest

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

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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.

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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(...)

Example

Demo.swift

ContentView.swift

App.swift

UITests.swift

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()
  }
}