Testing (eng)

iOS Testing
Derrick Chao @ Loopd

Frameworks
• XCTest
• OCMock
• KIF

XCTest
• XCTest is the testing framework in Xcode
• A test method is an instance method of a
test class that begins with the preﬁx test 
- (void)testExample {
// This is an example of a functional test case.
XCTAssert(YES, @"Pass");
XCTAssert(1+1==2);
XCTAssertTrue(1+1==2);
XCTAssertFalse(1+1==3);
}
• XCTAssert
XCTAssert(expression, …);
XCTAssertTrue(expression, …);
XCTAssertFalse(expression, ...);

Unit Test Example
- (void)testValidatePassword {
NSString *password1 = @"AbCd1234";
NSString *password3 = @"ABCD";
NSString *password5 = @"";
XCTAssertTrue([Helper validatePassword:password1]);
XCTAssertTrue([Helper validatePassword:password2]);
XCTAssertFalse([Helper validatePassword:password3]);
}

Test Async Function
Example
• send a message to another user
• async
• block callback

Test Async Function
Example
- (void)testSendMessageWithNilMessage {
XCTestExpectation *expectation =
[self expectationWithDescription:@"completion should be called"];
[Message sendMessage:nil recipientInfo:nil completion:^(id responseObject, NSError
*error) {
[expectation fulfill];
XCTAssertNotNil(error);
XCTAssert([error.userInfo[@"message"] isEqualToString:@"message can't be
nil"]);
}];
[self waitForExpectationsWithTimeout:2 handler:nil];
}

Singleton
// LoopdManager.h file
+ (instancetype)sharedManager;
// LoopdManager.m file
+ (instancetype)sharedManager {
static dispatch_once_t onceToken;
static LoopdManager *sharedInstance;
dispatch_once(&onceToken, ^{
sharedInstance = [[LoopdManager alloc] init];
});
return sharedInstance;
}

Test Singleton Example
- (void)testSharedManager {
LoopdManager *manager1 = [LoopdManager sharedManager];
LoopdManager *manager2 = [LoopdManager sharedManager];
LoopdManager *manager3 = [LoopdManager new];
XCTAssertNotNil(manager1);
XCTAssertNotNil(manager2);
XCTAssertEqual(manager1, manager2);
XCTAssertNotEqual(manager1, manager3);
}

OCMock
• mock objects are simulated objects that mimic the
behavior of real objects in controlled ways 
- (void)testMock {
id mockUserInfo = OCMClassMock([UserInfo class]);
// fullname should be nil for now
XCTAssertNil([mockUserInfo fullname]);
// make a custom return value
OCMStub([mockUserInfo fullname]).andReturn(@"David");
// fullname should be David now
XCTAssert([[mockUserInfo fullname] isEqualToString:@"David"]);
}

OCMock Example (1)
ListViewController has a collection view
find all SomeModel from server when viewDidLoad
// in SomeModel.h file 
@interface SomeModel : ModelObject
+ (void)findAllByCurrentUserId:(NSString *)currentUserId
completion:(ArrayResultBlock)completion;
@end

OCMock Example (2)
- (void)testCollectionViewCellNumber {
id mockSomeModel = OCMClassMock([SomeModel class]);
OCMStub([mockSomeModel findAllRelationshipsByCurrentUserId:[OCMArg any]
completion:[OCMArg
any]]).andDo(^(NSInvocation *invocation) {
ArrayResultBlock completion;
[invocation getArgument:&completion atIndex: 3];
NSArray *someModels = @[@“1”, @“2”, @“3”, @“4”, @“5”];
completion(someModels, nil);
});
ListViewController *listVC = [ListViewController new];
listVC.view;
NSInteger num = [listVC collectionView:nil numberOfItemsInSection:0];
XCTAssert(num == 5);
XCTAssert(num != 6);
}

KIF
• KIF iOS Integration Testing Framework

KIF Example
@interface UITests : KIFTestCase
@end
@implementation UITests
- (void)testLoginSteps {
[tester tapViewWithAccessibilityLabel:@"regular_button"];
[tester enterText:@"123@123.com" intoViewWithAccessibilityLabel:@"emailTextField"];
[tester enterText:@"abcdefg" intoViewWithAccessibilityLabel:@"passwordTextField"];
[tester tapViewWithAccessibilityLabel:@“checkmark_button"];
}
@end

MVC
• view can retrieve data
from model directly
• view hosts all the UI
controls
• high coupling

MVP
• MVP is a derivation of the
MVC architectural pattern
• view can’t retrieve data from
model directly
• low coupling

MVP's advantage
• easier to unit test, clean
separation of the View and Model
• maintainability of UI increases
due to almost no dependency on
business logic
• Usually view to presenter map
one to one. Complex views may
have multi presenters

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView
cellForItemAtIndexPath:(NSIndexPath *)indexPath {
UICollectionViewCell *cell = [collectionView
dequeueReusableCellWithReuseIdentifier:@"Cell"
forIndexPath:indexPath];
// config cell
Car *car = self.cars[indexPath.item];
cell.makeLabel.text = car.make;
cell.modelLabel.text = car.model;
cell.yearLabel.text = car.year;
cell.detailLabel.text = car.detail;
return cell;
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView
cellForItemAtIndexPath:(NSIndexPath *)indexPath {
UICollectionViewCell *cell = [collectionView
dequeueReusableCellWithReuseIdentifier:@"Cell"
forIndexPath:indexPath];
// config cell
Car *car = self.cars[indexPath.item];
cell.car = car;
[cell showUI];
return cell;
}

Test Cell
- (void)testCollectionViewCellNumber {
id mockSomeModel = OCMClassMock([SomeModel class]);
OCMStub([mockSomeModel findAllRelationshipsByCurrentUserId:[OCMArg any]
completion:[OCMArg
any]]).andDo(^(NSInvocation *invocation) {
ArrayResultBlock completion;
[invocation getArgument:&completion atIndex: 3];
NSArray *someModels = @[mod1, mod2, mod3, mod4, mod5];
completion(someModels, nil);
});
ListViewController *listVC = [ListViewController new];
listVC.view;
NSInteger num = [listVC collectionView:nil numberOfItemsInSection:0];
XCTAssert(num == 5);
XCTAssert(num != 6);
UICollectionViewCell *cell = [contactListVC collectionView:nil
cellForItemAtIndexPath:0];
}

Spike Solution
• not sure how to achieve some
requirement.

Spike Solution (2)
• A spike solution is dirty and quick.
Code just enough to get the answer
you need.
• Throw it away when you’re done with
it.

Spike Solution (3)
• open a new branch
• do some test in the branch
• Throw it away when you’re done with
it

TDD with Xcode
• requirement: a helper for add two
integers

TDD with Xcode (2)
• create ﬁles

TDD with Xcode (4)
• command+u

TDD with Xcode (5)
• verify the function

TDD with Xcode (6)
• ﬁnish the function then test again

how I feel for TDD at
beginning

beneﬁts of Testing/TDD
• test => spec
• saves you development time
• saves you development time
• Good unit testing forces good
architecture. In order to make your
code unit-testable, it must be properly
modularized, by writing the unit
testing ﬁrst various architectural
problems tend to surface earlier

references
• http://iosunittesting.com
• http://stackoverﬂow.com/questions/
1053406/why-does-apple-say-iphone-
apps-use-mvc
• http://blog.sanc.idv.tw/2011/09/uimvp-
passive-view.html

Testing (eng)

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