mobiai-ios-testing

iOS Testing

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Guide to writing and running tests in iOS projects.

When to Use

• Writing unit tests for Swift code
• Setting up test infrastructure
• Running and debugging test suites

Test Types

Type	Target	Framework	Speed
Unit	MyAppTests	XCTest	Fast
UI	MyAppUITests	XCUITest	Slow
Snapshot	MyAppTests	SnapshotTesting (pointfree)	Medium

Unit Testing (XCTest)

File Location

• Source: MyApp/Feature/MyViewModel.swift
• Test: MyAppTests/Feature/MyViewModelTests.swift

Test Structure

import XCTest
@testable import MyApp

final class MyViewModelTests: XCTestCase {

    private var sut: MyViewModel!
    private var mockRepository: MockRepository!

    override func setUp() {
        super.setUp()
        mockRepository = MockRepository()
        sut = MyViewModel(repository: mockRepository)
    }

    override func tearDown() {
        sut = nil
        mockRepository = nil
        super.tearDown()
    }

    func testLoadData_setsStateToSuccess_whenRepositoryReturnsData() async {
        // Given
        mockRepository.stubbedResult = [Item(id: "1", name: "Test")]

        // When
        await sut.loadData()

        // Then
        XCTAssertEqual(sut.state, .success([Item(id: "1", name: "Test")]))
    }

    func testLoadData_setsStateToError_whenRepositoryThrows() async {
        // Given
        mockRepository.stubbedError = NSError(domain: "", code: -1)

        // When
        await sut.loadData()

        // Then
        if case .error = sut.state {
            // Expected
        } else {
            XCTFail("Expected error state")
        }
    }
}

Naming Conventions

// Pattern: testMethodName_expectedBehavior_whenCondition
func testCalculateTotal_returnsZero_whenCartIsEmpty() { ... }
func testFormatPrice_throws_whenAmountIsNegative() { ... }