Unit Testing: Special Cases
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The 4th Dnepropetrovsk iOS Practice Leaders Community Meet-Up, which took place onThursday, September 25. Maxim Koshtenko, an iOS developer with 4+ years of experience in the area, held a presentation in which he told: - about the most widespread problems which appear while writing tests and how to solve them; - how to cover controllers with tests correctly and what should be visible in interface; - why tests do not work for block-based and asynchronous code and how we can fix this; - how to write tests for Core Data models; - many other useful and interesting tips and tricks. The presentation will be interesting for all iOS developers.
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Unit Testing: Special Cases
- 2. How to Test
- 3. UIViewControllers How to TestUnit Testing What Is Testing For?
- 4. UIViewControllers Block-based code ! How to TestUnit Testing What Is Testing For?
- 5. UIViewControllers Block-based code CoreData How to TestUnit Testing What Is Testing For?
- 8. IBOutlets & IBActions Outlet is connected
- 9. - (void)setUp { [super setUp]; sut = [ConverterViewController new]; } ! - (void)tearDown { sut = nil; [super tearDown]; } Is Outlet Connected?
- 10. - (void)setUp { [super setUp]; sut = [ConverterViewController new]; } ! - (void)tearDown { sut = nil; [super tearDown]; } ! - (void)testThatTextFieldOutletIsConnected { XCTAssertNotNil(sut.textField, @"outlet should be connected"); } Is Outlet Connected?
- 11. - (void)setUp { [super setUp]; sut = [ConverterViewController new]; } ! - (void)tearDown { sut = nil; [super tearDown]; } ! - (void)testThatTextFieldOutletIsConnected { XCTAssertNotNil(sut.textField, @"outlet should be connected"); } Is Outlet Connected?
- 12. - (void)setUp { [super setUp]; sut = [ConverterViewController new]; } ! - (void)tearDown { sut = nil; [super tearDown]; } ! - (void)testThatTextFieldOutletIsConnected { [sut view]; XCTAssertNotNil(sut.textField, @"outlet should be connected"); } Is Outlet Connected?
- 13. IBOutlets & IBActions Outlet has a right action.
- 14. - (void)testButtonActionBinding { [sut view]; NSArray* acts = [sut.button actionsForTarget:sut forControlEvent:UIControlEventTouchUpInside]; XCTAssert([acts containsObject:@"onButton:"], @"should use correct action"); } Is Action Connected?
- 15. IBOutlets & IBActions The action does the right things.
- 16. viewDidLoad Unit testing of a view controller nearly always means writing the view controller methods differently
- 17. viewDidLoad - should call helper methods
- 18. viewDidLoad - should call helper methods - each of the helper methods should do just one thing (SOLID principles)
- 19. viewDidLoad - should call helper methods - each of the helper methods should do just one thing (SOLID principles) - write tests for each of the helper methods
- 20. viewDidLoad - should call helper methods - each of the helper methods should do just one thing (SOLID principles) - write tests for each of the helper methods - test viewDidLoad calls helper methods (partial mock)
- 22. dealloc ❓hook dealloc method of SUT when setup
- 23. dealloc ❓hook dealloc method of SUT when setup ❓record calling of the hook
- 24. dealloc ❓hook dealloc method of SUT when setup ❓record calling of the hook ❓verify if hook is called after teardown
- 25. Aspects
- 26. /// Adds a block of code before/instead/after the current `selector` for a specific instance. - (id<AspectToken>)aspect_hookSelector:(SEL)selector withOptions:(AspectOptions)options usingBlock:(id)block error:(NSError **)error; ! /// Called after the original implementation (default) AspectPositionAfter, ! /// Will replace the original implementation. AspectPositionInstead, ! /// Called before the original implementation. AspectPositionBefore, Aspects
- 27. dealloc ✅ hook dealloc method of SUT when setup ❓ record calling of the hook ❓ verify if hook is called after teardown Aspects
- 28. dealloc ✅ hook dealloc method of SUT when setup ✅ record calling of the hook ❓ verify if hook is called after teardown Aspects instance var
- 29. dealloc ✅ hook dealloc method of SUT when setup ✅ record calling of the hook ✅ verify if hook is called after teardown Aspects instance var XCTAssert
- 30. @interface ConverterViewControllerTests : XCTestCase { ConverterViewController* sut; BOOL _sutDeallocated; } @end ! - (void)setUp { [super setUp]; sut = [ConverterViewController new]; _sutDeallocated = NO; [sut aspect_hookSelector:NSSelectorFromString(@"dealloc") withOptions:AspectPositionBefore usingBlock:^(id<AspectInfo> aspectInfo){ _sutDeallocated = YES; } error:nil]; } ! - (void)tearDown { sut = nil; XCTAssertTrue(_sutDeallocated, @"SUT is not deallocated"); [super tearDown]; } dealloc
- 31. @interface } @end ! - ( [ ! ! ! ! ! } ! - ( [ } dealloc ! ! ! ! ! ! ! ! ! ! [sut aspect_hookSelector:NSSelectorFromString(@"dealloc") withOptions:AspectPositionBefore usingBlock:^(id<AspectInfo> aspectInfo){ _sutDeallocated = YES; } error:nil];
- 32. UINavigationController - test push view controller - test pop view controller
- 35. UINavigationController But @interface UIViewController (UINavigationControllerItem) ! @property(nonatomic,readonly,retain) UINavigationController* navigationController; ! @end
- 36. -(void)testTappingDetailsShouldDisplayDetails { UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:sut]; id mockNav = [OCMockObject partialMockForObject:nav]; [[mockNav expect] pushViewController:[OCMArg any] animated:YES]; [sut onShowDetailsButton:nil]; [mockNav verify]; } UINavigationController
- 37. Choosing not to test view controllers is the decision not to test most of your code. UIViewController
- 38. Testing simple things is simple, and testing complex things is complex UIViewController
- 39. Block-based code Why does test fail?
- 40. Block-based code ! typedef void(^CompletionHandler)(NSArray * result); ! - (void)runAsyncCode:(CompletionHandler)completion { dispatch_async(dispatch_get_main_queue(), ^{ completion(nil); }); }
- 41. - (void)testRunAsyncCode { // arrange __block BOOL hasCalledBack = NO; ! // act [sut runAsyncCode:^(NSArray *result) { hasCalledBack = YES; }]; // assert XCTAssert(hasCalledBack, @"Test timed out"); } Block-based code
- 42. - (void)testRunAsyncCode { // arrange __block BOOL hasCalledBack = NO; ! // act [sut runAsyncCode:^(NSArray *result) { hasCalledBack = YES; }]; // assert XCTAssert(hasCalledBack, @"Test timed out"); } Block-based code
- 43. - (void)testRunAsyncCode { // arrange __block BOOL hasCalledBack = NO; ! // act [sut runAsyncCode:^(NSArray *result) { hasCalledBack = YES; }]; // assert XCTAssert(hasCalledBack, @"Test timed out"); } Block-based code
- 44. - (void)testRunAsyncCode { // arrange __block BOOL hasCalledBack = NO; ! // act [sut runAsyncCode:^(NSArray *result) { hasCalledBack = YES; }]; // assert XCTAssert(hasCalledBack, @"Test timed out"); } Block-based code
- 45. - (void)testRunAsyncCode { // arrange __block BOOL hasCalledBack = NO; ! // act [sut runAsyncCode:^(NSArray *result) { hasCalledBack = YES; }]; // assert XCTAssert(hasCalledBack, @"Test timed out"); } Block-based code
- 46. - (void)testRunAsyncCode { // arrange __block BOOL hasCalledBack = NO; ! // act [sut runAsyncCode:^(NSArray *result) { hasCalledBack = YES; }]; // assert XCTAssert(hasCalledBack, @"Test timed out"); } Block-based code
- 47. Block-based code What can we do?
- 48. Block-based code
- 49. - (void)testRunAsyncCode { // arrange __block BOOL hasCalledBack = NO; ! // act [sut runAsyncCode:^(NSArray *result) { hasCalledBack = YES; }]; // assert XCTAssert(hasCalledBack, @"Test timed out"); } Block-based code
- 50. - (void)testRunAsyncCode { // arrange __block BOOL hasCalledBack = NO; ! // act [sut runAsyncCode:^(NSArray *result) { hasCalledBack = YES; }]; // assert ! ! ! ! ! XCTAssert(hasCalledBack, @"Test timed out"); } Block-based code
- 51. - (void)testRunAsyncCode { // arrange __block BOOL hasCalledBack = NO; ! // act [sut runAsyncCode:^(NSArray *result) { hasCalledBack = YES; }]; // assert NSDate *timeout = [NSDate dateWithTimeIntervalSinceNow:0.1]; while([timeout timeIntervalSinceNow] > 0 && hasCalledBack == NO) { [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:timeout]; } XCTAssert(hasCalledBack, @"Test timed out"); } Block-based code
- 52. - (void)testRunAsyncCode { // arrange __block BOOL hasCalledBack = NO; ! // act [sut runAsyncCode:^(NSArray *result) { hasCalledBack = YES; }]; // assert NSDate *timeout = [NSDate dateWithTimeIntervalSinceNow:0.1]; while([timeout timeIntervalSinceNow] > 0 && hasCalledBack == NO) { [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:timeout]; } XCTAssert(hasCalledBack, @"Test timed out"); } Block-based code
- 53. Block-based code Also we can use: - (void)verifyWithDelay:(NSTimeInterval)delay { NSTimeInterval step = 0.01; while(delay > 0) { if([expectations count] == 0) break; NSDate* until = [NSDate dateWithTimeIntervalSinceNow:step]; [[NSRunLoop currentRunLoop] runUntilDate:until]; delay -= step; step *= 2; } [self verify]; } OCMock
- 54. CoreData
- 55. CoreData As long as you don't put business logic in your models, you don't have to test them.
- 56. CoreData creates setters & getters in run-time
- 57. CoreData creates setters & getters in run-time we can’t mock CoreData models
- 58. CoreData What can we do?
- 59. CoreData - create protocol that has all model’s properties defined
- 60. CoreData - create protocol that has all model’s properties defined - conform NSManagedObject to the protocol
- 61. CoreData - create protocol that has all model’s properties defined - conform NSManagedObject to the protocol - create NSObject model just for testing, conforms to the protocol and @synthesize properties
- 64. CoreData Have a better solution?
- 65. CoreData Create own CoreData stack for each test-case
- 66. - (void)setUp { [super setUp]; NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"SimpleInvoice" withExtension:@“momd"]; ! NSManagedObjectModel *mom = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL]; ! NSPersistentStoreCoordinator *psc = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:mom]; ! XCTAssertNotNil([psc addPersistentStoreWithType:NSInMemoryStoreType configuration:nil URL:nil options:nil error:NULL], @"Should be able to add in-memory store”); ! _moc = [[NSManagedObjectContext alloc] init]; _moc.persistentStoreCoordinator = psc; } CoreData
- 67. - (void { [ ! initWithContentsOfURL ! initWithManagedObjectModel ! ! ! ! ! ! ! ! } CoreData - (void)setUp { ! ! ! ! ! ! ! ! ! ! XCTAssertNotNil([psc addPersistentStoreWithType:NSInMemoryStoreType configuration:nil URL:nil options:nil error:NULL], @"Should be able to add in-memory store”); ! ! ! }
- 69. CoreData Advantages? - no additional classes
- 70. CoreData Advantages? - no additional classes - no dependence on external state
- 71. CoreData Advantages? - no additional classes - no dependence on external state - close approximation to the application environment
- 72. CoreData Advantages? - no additional classes - no dependence on external state - close approximation to the application environment - we are able to create base test class with a stack and subclass it where we need
- 73. CoreData Advantages? - no additional classes - no dependence on external state - close approximation to the application environment - we are able to create base test class with a stack and subclass it where we need
- 74. - (void)testFullNameReturnsСorrectString { Person* ps; ps = [NSEntityDescription insertNewObjectForEntityForName:@"Person" inManagedObjectContext:_moc]; ps.firstName = @"Tom"; ps.lastName = @“Lol"; ! STAssertTrue([[ps fullName] isEqualToString:@"Lol Tom"], @"should have matched full name"); } CoreData
- 75. CoreData - test model’s additional business-logic - test ManagedObjectModel for an entity - create and use models as a mocks
- 76. ✅ UIViewControllers ✅ Block-based code ✅ CoreData How to Test