iOS Unit Testing - Intro

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Transcript

1. Unit Testing
2. Unit Testing What Is Testing For?
3. Unit Testing When Should Software Be Tested? What Is Testing For?
4. What Is Testing For?
5. What Is Testing For? Testing can show that the product works!
6. When Should Software Be Tested?
7. Waterfall project management process"
8. Waterfall project management process" Requirements
9. Waterfall project management process" Requirements Specification
10. Waterfall project management process" Requirements Development Specification
11. Waterfall project management process" Requirements Test Development Specification
12. Waterfall project management process" Requirements Test Development Specification Deployment
13. Cost of Bugs Time Detected Time Introduced Requirements Architecture Coding System Test Post-" Release Requirements 1 3 5-10 10 10-100 Architecture - 1 10 15 25-100 Coding - - 1 10 10-25 Cost of Fixing Bugs Found at Different Stages of the Software Development Process
14. When Should Software Be Tested?
15. When Should Software Be Tested? Software should be tested all the time!
16. Unit Testing
17. What is Unit Test? Unit tests are small pieces of code that test the behavior of other code.
18. A test is not a unit test if: • It talks to the database" • It communicates across the network" • It touches the file system" • It can't run at the same time as any of your other unit tests" • You have to do special things to your environment (such as editing config files) to run it.
19. Properties of a Good Unit Test
20. A good unit test: is able to be fully automated
21. A good unit test: Tests a single logical concept in the system
22. A good unit test: Consistently returns the same result (no random numbers, save those for integration tests)
23. A good unit test: is Maintainable and order-independent
24. A good unit test: is Independent
25. A good unit test: Runs fast
26. A good unit test: is Readable
27. A good unit test: is Trustworthy (when you see its result, you don’t need to debug the code just to be sure)
28. A good unit test is: • Able to be fully automated! • Tests a single logical concept in the system" • Consistently returns the same result" • Maintainable and order-independent" • Independent! • Runs fast" • Readable! • Trustworthy
29. Verifications
30. Types of Verifications •Return Value" •State" •Behavior
31. Types of Verifications SUT
32. Types of Verifications SUT Behavior " (Indirect" Outputs) DOC
33. Types of Verifications SUT Setup Exercise Verify Tear Down Behavior " (Indirect" Outputs) DOC
34. Return Value Verification We inspect the value returned from the system under test and compare it to the expected state. SUT Setup Exercise Verify Tear Down Behavior " (Indirect" Outputs) DOC
35. State Verification We inspect the state of the system under test after it has been exercised and compare it to the expected state. SUT Setup Exercise Verify Tear Down Behavior " (Indirect" Outputs) DOC State
36. SUT Behavior Verification We capture the indirect outputs of the SUT as they occur and compare them to the expected behavior. Setup Exercise Verify Tear Down Behavior " (Indirect" Outputs) DOC
37. SUT Behavior Verification We capture the indirect outputs of the SUT as they occur and compare them to the expected behavior. Setup Exercise Verify Tear Down Behavior " (Indirect" Outputs) Fake Verify
38. XCTest
39. XCTest • Provided by Xcode" • New iOS application projects automatically include a unit testing target" • Test classes do not have a header file" • It’s not necessary to add application’s source files to the XCTest Target" • Each test case is a method with prefix test" • Xcode 5 allows to run tests from the editor
40. XCTest Flow Setup Tear Down Test - (void)setUp { [super setUp]; // This method is called before the invocation of each test method in the class. } - (void)tearDown { // This method is called after the invocation of each test method in the class. [super tearDown]; } - (void)testExample { XCTFail(@"No implementation for \"%s\"", __PRETTY_FUNCTION__); }
41. Test main actions: • Arrange objects, creating and setting them up as necessary. " • Act on an object. " • Assert that something is as expected. - (void)testMakeConversionWithModeMilesToKilometers { // Arrange sut.value = @(1); // Act [sut makeConversionWithMode:ConverterModeMilesToKm]; // Assert XCTAssertTrue([sut.text isEqualToString:@"1.609344"], @"should convert from miles to kilometers"); }
42. @interface ConverterModelTests : XCTestCase { ConverterModel* sut; } @end @implementation ConverterModelTests - (void)setUp { [super setUp]; sut = [ConverterModel new]; } - (void)tearDown { sut = nil; [super tearDown]; } - (void)testMakeConversionWithModeMilesToKilometers { // Arrange sut.value = @(1); // Act [sut makeConversionWithMode:ConverterModeMilesToKm]; // Assert XCTAssertTrue([sut.text isEqualToString:@"1.609344"], @"should convert from miles to kilometers"); } @end
43. XCTest Asserts • XCTFail (format…) • XCTAssertNil (a1, format…) • XCTAssertNotNil (a1, format…) • XCTAssert (a1, format…) • XCTAssertTrue (a1, format…) • XCTAssertFalse (a1, format…) • XCTAssertEqualObjects (a1, a2, format…) • XCTAssertEquals (a1, a2, format…) • XCTAssertEqualsWithAccuracy (a1, a2, accuracy, format…) • XCTAssertThrows (expression, format…) • XCTAssertThrowsSpecific (expression, exception, format…) • XCTAssertThrowsSpecificNamed (expression, exception, name, format…) • XCTAssertNoThrow (expression, format…) • XCTAssertNoThrowSpecific (expression, exception, format…) • XCTAssertNoThrowSpecificNamed (expression, exception, name, format…)
44. - (void)viewDidLoad { [super viewDidLoad]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(someAction:) name:kSomeNotification object:nil]; }
45. - (void)viewDidLoad { [super viewDidLoad]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(someAction:) name:kSomeNotification object:nil]; } - (void)testViewDidLoadAddsObserverForSomeNotification { // Arrange // Act // Assert }
46. Dependency Injection
47. Dependency Injection is a software design pattern that implements passing a service to a client, rather than allowing a client to build or find the service.
48. Constructor Injection the dependencies are provided through a class constructor - (id)initWithNotificationCenter:(NSNotificationCenter *)notificationCenter
49. Setter Injection the client exposes a setter method that the injector uses to inject the dependency @property (nonatomic, weak) NSUserDefaults* userDefaults;
50. Dependency Injection providing an instance variable for dependency
51. - (void)viewDidLoad { [super viewDidLoad]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(someAction:) name:kSomeNotification object:nil]; } Dependency - (void)testViewDidLoadAddsObserverForSomeNotification { // Arrange // Act // Assert }
52. - (id)initWithNotificationCenter:(NSNotificationCenter *)notificationCenter { self = [super init]; if(self) { _notificationCenter = notificationCenter; } return self; } - (void)viewDidLoad { [super viewDidLoad]; [_notificationCenter addObserver:self selector:@selector(someAction:) name:kSomeNotification object:nil]; } Inject Dependency
53. Mocks
54. is a fake object in the system that verifies the object under test interacted as expected with the fake object. Mock Object
55. It is common in unit tests to mock or stub collaborators of the system under test so that the test is independent of the implementation of the collaborators. Mock Object SUT Behavior Verification Setup Exercise Verify Tear Down Behavior " (Indirect" Outputs) Fake Verify
56. Test Mocks SUT communicates with the mock object, and all communication is recorded in the mock. The test uses the mock to verify that the test passes. SUT Mock Communicate Assert
57. Test Stubs Returns specified result for a message, stubs can’t fail the test. SUT Stub Communicate Assert
58. @interface ConverterViewController : UIViewController @property (nonatomic, weak) NSNotificationCenter* notificationCenter; @end @implementation ConverterViewController - (void)viewDidLoad { [super viewDidLoad]; [_notificationCenter addObserver:self selector:@selector(someAction:) name:kSomeNotification object:nil]; } @end Injected Dependency
59. @interface ConverterViewController : UIViewController @property (nonatomic, weak) NSNotificationCenter* notificationCenter; @end @implementation ConverterViewController - (void)viewDidLoad { [super viewDidLoad]; [_notificationCenter addObserver:self selector:@selector(someAction:) name:kSomeNotification object:nil]; } @end Injected Dependency Replace with a mock
60. What we need? •an object that responds to addObserver:selector:name:object:! •possibility to record a call" •check for notification’s name" •verification
61. @interface FakeNotificationCenter : NSObject { BOOL _hasCalled; } @property (nonatomic, strong) NSString* expectedName; - (void)addObserver:(id)observer selector:(SEL)aSelector name:(NSString *)aName object:(id)anObject; - (void)verify; @end @implementation FakeNotificationCenter - (void)addObserver:(id)observer selector:(SEL)aSelector name:(NSString *)aName object:(id)anObject { _hasCalled = [_expectedName isEqualToString:aName]; } - (void)verify { NSAssert(_hasCalled, @"expected method was not called with specified parameters"); } @end What we can do
62. - (void)testViewDidLoadAddsObserverForSomeNotification { // Arrange FakeNotificationCenter* fake = [FakeNotificationCenter new]; fake.expectedName = kSomeNotification; sut.notificationCenter = (id)fake; // Assert [fake verify]; } How can we use it?
63. - (void)testViewDidLoadAddsObserverForSomeNotification { // Arrange FakeNotificationCenter* fake = [FakeNotificationCenter new]; fake.expectedName = kSomeNotification; sut.notificationCenter = (id)fake; // Assert [fake verify]; } -[ConverterViewControllerTests testViewDidLoadAddsObserver] failed: expected method was not called with specified parameters How can we use it?
64. - (void)testViewDidLoadAddsObserverForSomeNotification { // Arrange FakeNotificationCenter* fake = [FakeNotificationCenter new]; fake.expectedName = kSomeNotification; sut.notificationCenter = (id)fake; // Act [sut viewDidLoad]; // Assert [fake verify]; } How can we use it?
65. OCMock
66. OCMock Provides •stub objects that return pre-determined values for specific method invocations" •dynamic mocks that can be used to verify interaction patterns" •partial mocks to overwrite selected methods of existing objects
67. Mocks // Creates a mock object that can be used as if it were an instance of // SomeClass. id mock = [OCMockObject mockForClass:[SomeClass class]]; // Tells the mock object that someMethod: should be called with an argument // that is equal to someArgument. [[mock expect] someMethod:someArgument]; // After this setup the functionality under test should be invoked // followed by [mock verify]; // When a method is called on a mock object that has not been set up with // either expect or stub the mock object will raise an exception. This // fail-fast mode can be turned off by creating a "nice" mock: id mock = [OCMockObject niceMockForClass:[SomeClass class]]; // While nice mocks will simply ignore all unexpected methods it is // possible to disallow specific methods: [[mock reject] someMethod];
68. Stubs // Tells the mock object that when someMethod: is called with // someArgument it should return aValue. [[[mock stub] andReturn:aValue] someMethod:someArgument]; // It is not possible to pass primitive types directly. [[[mock stub] andReturnValue:@YES] aMethodReturnABoolean:someArgument]; // The mock object can also throw an exception or post a notification // when a method is called [[[mock stub] andThrow:anException] someMethod:someArgument]; [[[mock stub] andPost:aNotification] someMethod:someArgument]; // If Objective-C blocks are available a block can be used to handle the // invocation and set up a return value void (^theBlock)(NSInvocation *) = ^(NSInvocation *invocation) { /* code that reads and modifies the invocation object */ }; [[[mock stub] andDo:theBlock] someMethod:[OCMArg any]];
69. @interface ConverterViewController : UIViewController @property (nonatomic, weak) NSNotificationCenter* notificationCenter; @end @implementation ConverterViewController - (void)viewDidLoad { [super viewDidLoad]; [_notificationCenter addObserver:self selector:@selector(someAction:) name:kSomeNotification object:nil]; } @end Injected Dependency
70. - (void)testViewDidLoadAddsObserver { // Arrange id mock = [OCMockObject mockForClass:[NSNotificationCenter class]]; [[mock expect] addObserver:sut selector:[OCMArg anySelector] name:kConverterModelDidUpdateNotification object:OCMOCK_ANY]; sut.notificationCenter = mock; // Act [sut viewDidLoad]; // Assert [mock verify]; } How we test this with OCMock
71. Legacy Code?
72. How to start with Existing Project • All developers in team must write and run tests
73. How to start with Existing Project • All developers in team must write and run tests" • Start with warnings and bugs
74. How to start with Existing Project • All developers in team must write and run tests" • Start with warnings and bugs! • Isolate modules and classes
75. How to start with Existing Project • All developers in team must write and run tests" • Start with warnings and bugs! • Isolate modules and classes! • Don’t miss refactoring
76. How to start with Existing Project • All developers in team must write and run tests" • Start with warnings and bugs! • Isolate modules and classes! • Don’t miss refactoring! • Increase test-coverage step-by-step with new functionality
77. Demo Code https:/ /github.com/maksumko/ConverterApp" maksum.ko
78. Sources http:/ /www.amazon.com/Art-Unit-Testing-Examples-Net/dp/1933988274" http:/ /www.amazon.com/Test-Driven-iOS-Development-Developers-Library/dp/0321774183" http:/ /www.amazon.com/Growing-Object-Oriented-Software-Guided-Tests/dp/0321503627 " http:/ /martinfowler.com/articles/mocksArentStubs.html"
79. Questions?