Unit testing in xcode 8 with swift

Unit Testing in Xcode 8.3.2 with Swift3 Allan Shih

Agenda ● What is Unit Testing? ● Unit Testing in Xcode ● Create a Unit Testing class ● Write a Unit Testing class ● Test Asynchronous Operations ● Faking Objects and Interactions ● Demo ● Reference

What is Unit Testing? ● Unit testing, a testing technique using which individual modules are tested to determine if there are any issues by the developer himself. ● It is concerned with functional correctness of the standalone modules.

Unit Testing - Advantages ● Reduces Defects in the Newly developed features ● Reduces bugs when changing the existing functionality. ● Reduces Cost of Testing as defects are captured in very early phase. ● Improves design and allows better refactoring of code. ● Unit Tests, when integrated with build gives the quality of the build as well.

Unit Tests Main Properties ● Independent ○ Running a Unit Test should not affect another Unit Test run. Execution order is not important. ● Fast ○ A test which takes several seconds to run is not a Unit Test and probably needs a refactor. ● Isolated ○ Unit Test should not depend on external systems. They need to know their collaborators answers.

Create a project with Unit Tests

Creating a Unit Test Target in an existing project 1. Click the test navigator 2. Click the + button 3. Select “New Unit Test Target” 4. Create a Unit Test target

Build Settings > Deployment > iOS Deployment Target

Update CocoaPods ● Update a Podfile, and add test target dependencies: ● Run $ pod update in project directory. ● Open App.xcworkspace and build. target 'ThingMakerMvc' do use_frameworks! pod 'Alamofire', '~> 4.3' target 'ThingMakerMvcTests' do inherit! :search_paths end end

Run the test class 1. ProductTest or Command-U. This actually runs all test classes. 2. Click the arrow button in the test navigator. 3. Click the diamond button in the gutter.

Unit Test Class Structure ● Class Setup/TearDown ○ Executed once when the Unit Test class is initialized, not for every test in the class. Useful to avoid test code duplication at class level. ● Test Setup/TearDown ○ Executed once before and after each executed Unit Test. Useful to avoid test code duplication at test level. ● Test Methods ○ The Unit Test implementation itself. Here is where the test run and validations happens.

Test Setup / Tear Down Example @available(iOS 9.0, *) UIViewController.loadViewIfNeeded()

Tests Naming ● Use descriptive test names. It will provide quick feedback when test fails. ● Choose names which in few words says: ○ Method under testing ○ Condition under testing ○ Expected result / behavior

Tests Naming Example ● Good examples ○ testSyncLullabyList_withLullabyManager_return3LullabyItems() ○ testSyncStationList_withIHeartRadioApi_return6StationItems() ● Bad examples ○ testExample1() ○ testExample2() ○ testExample3()

Test Method Organization ● Arrange / Setup ○ Prepare all needed objects/dependencies for test execution. ● Act / Test ○ Test itself it performed, calling one specific method in the system under testing. ● Assert / Verify ○ Method result/behavior verification is performed at the end, using test asserts.

Tests Verification Types ● Return Value / State Verification ○ Verify the result returned for the method under test, no matter which interactions with other objects has been made. Useful and preferred verification in most cases. ● Behavior Verification ○ Verify that all tested method interactions among other collaboration objects are the expected one (generally done using mocks). Useful for some cases where interactions are important (for example a cache implementation).

Return Value Verification Example

XCTAssert Family in XCode 8.3.2 XCTAssert Family Description XCTAssert Asserts that an expression is true. XCTAssertTrue Asserts that an expression is true. XCTAssertFalse Asserts that an expression is false. XCTAssertNil Asserts that an expression is nil. XCTAssertNotNil Asserts that an expression is not nil. XCTAssertEqual Asserts that two expressions have the same value. XCTAssertEqualObjects Asserts that two objects are considered equal.

XCTAssert Family in XCode 8.3.2 XCTAssert Family Description XCTAssertNotEqual Asserts that two expressions do not have the same value. XCTAssertNotEqualObjects Asserts that an expression is true. XCTAssertGreaterThan Asserts that the value of one expression is greater than another. XCTAssertGreaterThanOrEqual Asserts that the value of one expression is greater than or equal to another. XCTAssertLessThan Asserts that the value of one expression is less than another. XCTAssertLessThanOrEqual Asserts that the value of one expression is less than or equal to another.

XCTAssert Family in XCode 8.3.2 XCTAssert Family Description XCTAssertThrowsError Asserts that an expression throws an error. XCTAssertNoThrow Asserts that an expression does not throw an NSException.

Demo Write a Unit Testing class

XCTestExpectation ● Define an expectation with a meaningful description. ● Go on with the test setup and exercise phases, calling the asynchronous method and fulfilling the expectation at the end of the callback closure. ● Make the test runner wait for you expectation to be fulfilled, so that the asynchronous operations can be completed and you assertions verified.

Demo Test Asynchronous Operations

Asynchronous Tests Problem ● Most apps interact with system or library objects, but you don’t control these objects. ● Tests that interact with these objects can be slow and unrepeatable. ● The singletons made our class hard to test.

Dependency Injection ● Extract and Override ○ Create a testing subclass and override the testing method. ● Method Injection ○ Pass a dependency object during a method. ● Property Injection ○ An internal or public property can be modified or replaced. ● Constructor Injection ○ Pass a dependency object during the constructor.

Sync Lullaby with LullabyManager

Extract and Override Example - Create a Mock Class

Extract and Override Example - Verifying Lullaby List

Method Injection Example - Create a property that holds a reference

Method Injection Example - Dependency object can be replaced

Method Injection Example - Use a mock LullabyManager object

Property Injection Example - Create a internal or public property

Property Injection Example - Use a mock LullabyManager object

Constructor Injection Example - Default Constructor

Constructor Injection Example - Dependency object can be replaced

Constructor Injection Example - Use a mock LullabyManager object

Types of Test Doubles ● Stub ○ Fakes a response to method calls of an object. ● Mock ○ Let you check if a method call is performed or if a property is set.

Mock Example - Create a Mock Class

Reference ● About Testing with Xcode - Apple ● Unit Testing in Xcode 7 with Swift - AppCoda ● iOS Unit Testing and UI Testing Tutorial - RayWenderlich ● Test Doubles: Mocks, Stubs, and More - objc ● MCE 2014: Jon Reid - Test Driven Development for iOS ● Waiting in XCTest

Unit testing in xcode 8 with swift

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