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.

1. 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?

6. UIViewController

7. IBOutlets & IBActions
viewDidLoad
dealloc
UINavigationController
UIViewController

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)

21. dealloc
setUp tearDown zombie

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

33. UINavigationController

34. UINavigationController
But

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

62. CoreData
Protocol
Model<Protocol> TestModel<Protocol>

63. CoreData
Protocol
Model<Protocol> TestModel<Protocol>

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”);
!
!
!
}

68. CoreData
Advantages?

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

77. Video is coming!
https://github.com/maksum
!
maksum.ko
contact me:

78. Sources
http://www.amazon.com/Test-Driven-iOS-Development-Developers-Library/dp/
0321774183
!
http://www.objc.io/issue-1/testing-view-controllers.html
http://www.silverbaytech.com/2013/02/25/ios-testing-part-3-testing-view-controller/
http://iosunittesting.com/unit-testing-view-controllers/
http://blog.carbonfive.com/2010/03/10/testing-view-controllers/
!
http://iosunittesting.com/how-to-unit-test-completion-blocks/
!
http://iosunittesting.com/unit-testing-core-data/
http://ashfurrow.com/blog/unit-testing-with-core-data-models
http://www.sicpers.info/2010/06/template-class-for-unit-testing-core-data-entities/
http://iamleeg.blogspot.com/2010/01/unit-testing-core-data-driven-apps-fit.html