Последние полтора года на каждой из наших встреч мы рассказываем о том, почему продуманная и чистая архитектура мобильных приложений — это нужно и важно. За попытками спроектировать серебряную пулю мы очень часто забываем — или просто не уделяем достаточно внимания менее заметной части нашего кода — тестам. Егор Толстой расскажет о том, почему не стоит обделять вниманием unit-тесты, как подходить к их проектированию и осуществлять постепенный рефакторинг. Выступление, как обычно, подкреплено зарядом личной боли и опыта от поддержки базы в 3.000 unit-тестов на одном проекте и 1.000 на другом. Rambler.iOS - митапы iOS-разработчиков, организуемые компанией RAMBLER&Co.

1. Чистые
unit-тесты

2. What makes a clean test?
Three things. Readability, readability, and readability.
Robert C. Martin, «Clean Code»

3. #добришко

4. - (void)testLoadAlbums {
NSError *err1 = [NSError errorWithDomain:@"" code:123 userInfo:nil];
OCMStub([self.provider getAlbumsWithResultBlock:OCMOCK_ANY]).andDo(block);
[self waitForExpectationsWithTimeout:1. handler:^(NSError *localError) {
OCMVerify([self.provider getAlbumsWithResultBlock:OCMOCK_ANY]);
}];
}
4

5. - (void)testLoadAlbums {
NSError *err1 = [NSError errorWithDomain:@"" code:123 userInfo:nil];
OCMStub([self.provider getAlbumsWithResultBlock:OCMOCK_ANY]).andDo(block);
[self waitForExpectationsWithTimeout:1. handler:^(NSError *localError) {
OCMVerify([self.provider getAlbumsWithResultBlock:OCMOCK_ANY]);
}];
}
5

6. - (void)testLoadAlbums {
NSError *err1 = [NSError errorWithDomain:@"" code:123 userInfo:nil];
OCMStub([self.provider getAlbumsWithResultBlock:OCMOCK_ANY]).andDo(block);
[self waitForExpectationsWithTimeout:1. handler:^(NSError *localError) {
OCMVerify([self.provider getAlbumsWithResultBlock:OCMOCK_ANY]);
}];
}
6

7. - (void)testLoadAlbums {
NSError *err1 = [NSError errorWithDomain:@"" code:123 userInfo:nil];
OCMStub([self.provider getAlbumsWithResultBlock:OCMOCK_ANY]).andDo(block);
[self waitForExpectationsWithTimeout:1. handler:^(NSError *localError) {
OCMVerify([self.provider getAlbumsWithResultBlock:OCMOCK_ANY]);
}];
}
7

8. - (void)testDeletingMessages {
NSMutableArray *messages = [NSMutableArray new];
NSManagedObjectContext *ctx = [NSManagedObjectContext MR_contextForCurrentThread];
[messages addObject:message];
}
XCTestExpectation *expectation = [self expectationWithDescription:
[NSString stringWithFormat:@"%s", __PRETTY_FUNCTION__]];
[self.service deleteMessages:messages withResultBlock:^(NSError *error) {
[expectation fulfill];
}];
}
8

9. - (void)testDeletingMessages {
NSMutableArray *messages = [NSMutableArray new];
NSManagedObjectContext *ctx = [NSManagedObjectContext MR_contextForCurrentThread];
[messages addObject:message];
}
XCTestExpectation *expectation = [self expectationWithDescription:
[NSString stringWithFormat:@"%s", __PRETTY_FUNCTION__]];
[self.service deleteMessages:messages withResultBlock:^(NSError *error) {
[expectation fulfill];
}];
}
9

10. - (void)testDeletingMessages {
NSMutableArray *messages = [NSMutableArray new];
NSManagedObjectContext *ctx = [NSManagedObjectContext MR_contextForCurrentThread];
[messages addObject:message];
}
XCTestExpectation *expectation = [self expectationWithDescription:
[NSString stringWithFormat:@"%s", __PRETTY_FUNCTION__]];
[self.service deleteMessages:messages withResultBlock:^(NSError *error) {
[expectation fulfill];
}];
}
10

11. - (void)testDeletingMessages {
NSMutableArray *messages = [NSMutableArray new];
NSManagedObjectContext *ctx = [NSManagedObjectContext MR_contextForCurrentThread];
[messages addObject:message];
}
XCTestExpectation *expectation = [self expectationWithDescription:
[NSString stringWithFormat:@"%s", __PRETTY_FUNCTION__]];
[self.service deleteMessages:messages withResultBlock:^(NSError *error) {
[expectation fulfill];
}];
}
11

12. Зачем нужны чистые тесты
Как писать чистые тесты
Рефакторим тест
12

13. Зачем нужны чистые тесты
Как писать чистые тесты
Рефакторим тест
13

14. 14

15. /**
@author Egor Tolstoy
Метод возвращает закешированные результаты поиска для определенной
поисковой строки
@param searchTerm Поисковая строка
@return Результаты поиска
*/
- (NSArray *)obtainSearchResultsForSearchTerm:(NSString *)searchTerm;
15

16. @implementation PeopleServiceImplementationTests
- (void)testThatService {
}
- (void)testThatService {
}
- (void)testThatService {
}
- (void)testThatService {
}
@end
16

17. @implementation PeopleServiceImplementationTests
- (void)testThatService {
}
- (void)testThatService {
}
- (void)testThatService {
}
- (void)testThatService {
}
@end
17

18. @implementation PeopleServiceImplementationTests
- (void)testThatService {
}
- (void)testThatService {
}
- (void)testThatService {
}
- (void)testThatService {
}
@end
18

19. @implementation PeopleServiceImplementationTests
- (void)testThatService {
}
- (void)testThatService {
}
- (void)testThatService {
}
- (void)testThatService {
}
@end
19

20. @implementation PeopleServiceImplementationTests
- (void)testThatService {
}
- (void)testThatService {
}
- (void)testThatService {
}
- (void)testThatService {
}
@end
20

21. /**
Метод возвращает закешированные результаты поиска для определенной
поисковой строки
@param searchTerm Поисковая строка
@return Результаты поиска
*/
+
...ServiceReturnsCachedSearchResultsForCorrectQuery
...ServiceReturnsNilWhenNoResults
...ServiceReturnsNilForInvalidCharacters
...ServiceInterpretsDashesAsUnderscores
21

22. Грязные тесты > Тяжело поддерживать >
Удаление тестов > Падает качество проекта
22

23. Грязные тесты > Тяжело поддерживать >
Удаление тестов > Падает качество проекта
23

24. Грязные тесты > Тяжело поддерживать >
Удаление тестов > Падает качество проекта
24

25. Грязные тесты > Тяжело поддерживать >
Удаление тестов > Падает качество проекта
25

26. Зачем нужны чистые тесты
Как писать чистые тесты
Рефакторим тест
26

27. Чистый тест
предметно-ориентированный язык
без лишнего контекста
тестируется одно поведение системы
27

28. Предметно-ориентированный язык
Хорошо
XCTAssertEqualObjects(testAlbumError, expectedError);
- (void)testThatServiceReturnsNilWhenNoResults
[self setupStateWithBlockedUser];
Плохо
XCTAssertEqualObjects(err1, err2);
- (void)testNil
[self setupTestData];
28

29. Нет лишнего контекста
Хорошо
[self stubServiceCompletionBlockWithError:error];
- (void)setUp {}
Плохо
...[invocation getArgument:&result atIndex:3];...
... self.interactor.output = OCMProtocolMock(...);...
29

30. Тестируем одно поведение
Хорошо
...
XCTAssertTrue(viewReloaded);
XCTAssertTrue(newDataIsShown);
Плохо
...
XCTAssertTrue(newUserSaved);
XCTAssertFalse(viewReloaded);
XCTAssertNil([self.service obtainSearchHistory]);
30

31. OCMExpect([self.mockView setupInitialStateWithMenuItems:[OCMArg checkWithBlock:^BOOL(NSArray
*menuItems) {
__block BOOL correctSelectors = YES;
[menuItems enumerateObjectsUsingBlock:^(ItemViewModel *menuItem, NSUInteger idx, BOOL stop) {
NSString *expectedSelector = selectors[idx];
if (![expectedSelector isEqualToString:NSStringFromSelector(menuItem.tapSelector)]) {
correctSelectors = NO;
}
}];
return correctSelectors && menuItems.count == selectors.count;
}]]);
31

32. OCMExpect([self.mockView setupInitialStateWithMenuItems:[OCMArg checkWithBlock:^BOOL(NSArray
*menuItems) {
__block BOOL correctSelectors = YES;
[menuItems enumerateObjectsUsingBlock:^(ItemViewModel *menuItem, NSUInteger idx, BOOL stop) {
NSString *expectedSelector = selectors[idx];
if (![expectedSelector isEqualToString:NSStringFromSelector(menuItem.tapSelector)]) {
correctSelectors = NO;
}
}];
return correctSelectors && menuItems.count == selectors.count;
}]]);
self.mockView = [MockMenuView new];
XCTAssertTrue(self.mockView.areAllSelectorsCorrect);
32

33. // Случайная строка
NSString *string = [[NSUUID UUID] UUIDString];
// Произвольная ошибка
NSError *error = [NSError errorWithDomain:@"TestDomain" code:0 userInfo:nil];
33

34. // Случайная строка
NSString *string = [[NSUUID UUID] UUIDString];
// Произвольная ошибка
NSError *error = [NSError errorWithDomain:@"TestDomain" code:0 userInfo:nil];
NSString *string = [MockGenerator generateMockString];
NSError *error = [MockGenerator generateMockError];
34

35. - (void)setUp {
[super setUp];
RamblerInitialAssemblyCollector *collector = [RamblerInitialAssemblyCollector new];
NSArray *assemblyClasses = [collector collectInitialAssemblyClasses];
NSMutableArray *collaboratingAssemblies = [NSMutableArray array];
for (Class assemblyClass in assemblyClasses) {
if (assemblyClass == [NetworkAssembly class]) {
continue;
}
TyphoonAssembly *assembly = [assemblyClass new];
[collaboratingAssemblies addObject:assembly];
}
NetworkAssembly *networkAssembly = [NetworkAssembly new];
[networkAssembly activateWithCollaboratingAssemblies:collaboratingAssemblies];
[networkAssembly inject:self];
}
35

36. - (void)setUp {
[super setUp];
RamblerInitialAssemblyCollector *collector = [RamblerInitialAssemblyCollector new];
NSArray *assemblyClasses = [collector collectInitialAssemblyClasses];
NSMutableArray *collaboratingAssemblies = [NSMutableArray array];
for (Class assemblyClass in assemblyClasses) {
if (assemblyClass == [NetworkAssembly class]) {
continue;
}
TyphoonAssembly *assembly = [assemblyClass new];
[collaboratingAssemblies addObject:assembly];
}
NetworkAssembly *networkAssembly = [NetworkAssembly new];
[networkAssembly activateWithCollaboratingAssemblies:collaboratingAssemblies];
[networkAssembly inject:self];
[MagicalRecord setupInMemoryCoreData];
}
- (void)setUp {
[self setUpWithAssemblyClass:[NetworkAssembly class]];
}
36

37. - (void)testThatServiceLoadsSessionProfileSuccessfully {
NSError *resultError;
// большой блок логики загрузки профиля
XCTAssertNil(resultError);
}
- (void)testThatServiceLoadsSessionProfileWithError {
NSError *expectedError = [MockObjectsFactory generateGeneralError];
// большой блок логики загрузки профиля
XCTAssertEqualObjects(resultError, expectedError);
}
37

38. - (void)testThatServiceLoadsSessionProfileSuccessfully {
NSError *resultError;
// большой блок логики загрузки профиля
XCTAssertNil(resultError);
}
- (void)testThatServiceLoadsSessionProfileWithError {
NSError *expectedError = [MockObjectsFactory generateGeneralError];
// большой блок логики загрузки профиля
XCTAssertEqualObjects(resultError, expectedError);
}
- (void)testThatServiceLoadsProfileSuccessfully {
[self verifyThatServiceLoadsProfileWithError:nil];
}
- (void)testThatServiceLoadsProfileWithError {
[self verifyThatServiceLoadsProfileWithError:error];
}
- (void)verifyThatServiceLoadsProfileWithError:(id)error {
...
}
38

39. - (void)testThatPresenterStartsObservePost {
NSString *postId = [MockObjectsFactory generateGeneralString];
[self.presenter configureCurrentModuleWithPostId:postId];
[self.presenter didTriggerViewReadyEvent];
OCMVerify([self.mockInteractor startObserveChangesWithPostId:postId]);
}
39

40. - (void)testThatPresenterStartsObservePost {
NSString *postId = [MockObjectsFactory generateGeneralString];
[self.presenter configureCurrentModuleWithPostId:postId];
[self.presenter didTriggerViewReadyEvent];
OCMVerify([self.mockInteractor startObserveChangesWithPostId:postId]);
}
- (void)testThatPresenterStartsObservePost {
// given
NSString *postId = [MockObjectsFactory generateGeneralString];
[self.presenter configureCurrentModuleWithPostId:postId];
// when
[self.presenter didTriggerViewReadyEvent];
// then
OCMVerify([self.mockInteractor startObserveChangesWithPostId:postId]);
}
40

41. Зачем нужны чистые тесты
Как писать чистые тесты
Рефакторим тест
41

42. OperationScheduler
queue1 queue2
NSOperation NSOperation
42

43. NSArray *operations = self.generalQueue.operations;
for (NSOperation *generalOperation in operations) {
[generalOperation addDependency:operation];
}
[self.authQueue addOperation:operation];
43

44. • Передаем initialOperation в Планировщик
• Передаем в Планировщик 5 generalOperation
• При выполнении initialOperation создает authOperation
initial > authorization > general (5x)
44

45. - (void)testThatAuthOperationBlocksGeneralOperations {
// given
XCTestExpectation *expectation = [self expectationForCurrentTest];
NSMutableArray *operationNames = [NSMutableArray array];
NSString *const kAuthOperationName = @"AuthOperation";
NSString *const kInitialOperationName = @"InitialOperation";
NSString *const kGeneralOperationName = @"GeneralOperation";
NSUInteger const kGeneralOperationsCount = 5;
__block NSNumber *operationCounter = @0;
NSBlockOperation *authOperation = [NSBlockOperation blockOperationWithBlock:^{
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
@synchronized(operationNames) {
[operationNames addObject:kAuthOperationName];
}
[NSThread sleepForTimeInterval:0.05];
});
}];
NSBlockOperation *initialOperation = [NSBlockOperation blockOperationWithBlock:^{
@synchronized(operationNames) {
[operationNames addObject:kInitialOperationName];
}
[self.scheduler addAuthOperation:authOperation];
}];
// when
[self.scheduler addGeneralOperation:initialOperation];
for (NSUInteger i = 0; i < kGeneralOperationsCount; i++) {
NSBlockOperation *generalOperation = [NSBlockOperation blockOperationWithBlock:^{
@synchronized(operationNames) {
[operationNames addObject:kGeneralOperationName];
}
@synchronized(operationCounter) {
operationCounter = @([operationCounter integerValue] + 1);
if ([operationCounter integerValue] == kGeneralOperationsCount) {
dispatch_async(dispatch_get_main_queue(), ^{
[expectation fulfill];
});
}
}
}];
[self.scheduler addGeneralOperation:generalOperation];
}
// then
[self waitForExpectationsWithTimeout:kTestExpectationTimeout handler:^(NSError *error) {
XCTAssertEqualObjects(operationNames[0], kInitialOperationName);
XCTAssertEqualObjects(operationNames[1], kAuthOperationName);
for (NSUInteger i = 2; i < kGeneralOperationsCount; i++) {
XCTAssertEqualObjects(operationNames[i], kGeneralOperationName);
}
}];
}
45

46. XCTestExpectation *expectation =
[self expectationWithDescription:@"Last operation fired"];
XCTestExpectation *expectation =
[self expectationForCurrentTest];
46

47. NSString *const kAuthOperationName = @"AuthOperation";
NSString *const kInitialOperationName = @"InitialOperation";
NSString *const kGeneralOperationName = @"GeneralOperation";
OperationSchedulerTestConstants.h
47

48. NSBlockOperation *authOperation = [NSBlockOperation withBlock:^{
dispatch_async(..., ^{
@synchronized(operationNames) {
[operationNames addObject:authName];
}
[NSThread sleep:0.05];
});
}];
48

49. @interface TestBlockingByAuthOperationEnvironment : NSObject
- (void)setupWithTestCase:(XCTestCase *)testCase
operationsCount:(NSUInteger)operationsCount
initialBlock:(Block)initialBlock;
@property NSBlockOperation *initialOperation;
@property NSBlockOperation *authOperation;
@property NSArray *generalOperations;
@property NSArray *firedOperationNames;
@end
49

50. TestBlockingByAuthOperationEnvironment *environment =
[TestBlockingByAuthOperationEnvironment new];
[environment setupWithTestCase:self
operationsCount:kGeneralOperationsCount
initialBlock:^{
[self.scheduler addAuthOperation:environment.authOperation];
for (NSOperation *operation in environment.generalOperations) {
[self.scheduler addGeneralOperation:operation];
}
}];
50

51. - (void)testThatAuthOperationBlocksGeneralOperations {
// given
NSUInteger const kGeneralOperationsCount = 5;
TestBlockingByAuthOperationEnvironment *environment = [TestBlockingByAuthOperationEnvironment new];
[environment setupEnvironmentWithTestCase:self
generalOperationsCount:kGeneralOperationsCount
initialOperationBlock:^{
[self.scheduler addAuthOperation:environment.authOperation];
for (NSOperation *operation in environment.generalOperations) {
[self.scheduler addGeneralOperation:operation];
}
}];
// when
[self.scheduler addGeneralOperation:environment.initialOperation];
// then
[self waitForExpectationsWithTimeout:kTestExpectationTimeout handler:^(NSError *error) {
[self verifyCorrectOperationOrder:kTestOrder];
}];
}
51

52. Предметно-ориентированный язык
Нет лишнего контекста
Тестируем одно поведение
52

53. What makes a clean test?
Three things.
Readability, readability,
and readability.
Егор Толстой
@igrekde