外部依賴所造成的問題，用Protocol與mock的方式去破除依賴。

1. iOS
Unit testing II
Liyao Chen @ KKBOX

2. Outlines
• External dependency
• 透過 Protocol 依賴注⼊入解套
• 透過隔離框架解套

3. External dependency

4. –Roy Osherove
是系統中的⼀一個對象，
被測試的程式碼會與其互動，但是你不能控制它。
External dependency
(⾦金迎 譯)

5. External dependency
(

6. External dependency
你跟著師⽗父去幫別⼈人佈線安裝電燈，師⽗父三兩下
就搞定了，然後請你確認有沒有裝好，請問你會
怎麼做?
打開開關看看電燈有沒有跟著亮
再關上開關看電燈有沒有跟著暗

7. External dependency
⼀一個⽉月後客⼾戶打來說電燈打不開，請你們去檢
查，你第⼀一時間會想到的問題是什麼?
可能開關壞掉了?
可能電線沒接好?
可能電線壞掉了?

8. External dependency
可能電線壞掉了?
可能開關壞掉了?
可能電線沒接好?

9. External dependency

10. External dependency
static NSTimeInterval const yearInterval = 60*60*24*30*12;
@interface LCWire ()
@property (strong, nonatomic) NSDate *expiryDate;
@end
@implementation LCWire
- (instancetype)init
{
if(self = [super init]){
// 製造⽇日期為 2010/10/10
NSDateComponents *comps = [[NSDateComponents alloc] init];
[comps setDay:10];
[comps setMonth:10];
[comps setYear:2010];
NSDate *manufacturedDate = [[NSCalendar currentCalendar] dateFromComponents:comps];
// 有效期限為兩年
_expiryDate = [manufacturedDate dateByAddingTimeInterval:yearInterval*2];
}
return self;
}
- (BOOL)isExpired
{
return [[NSDate date] timeIntervalSinceReferenceDate] > [self.expiryDate
timeIntervalSinceReferenceDate];
}
@end

11. Break dependency

12. Break dependency
Dummy class
Fake

13. Dummy class
A class that implements an interface
but contains fixed data and no logic.
– Sangdol

14. Dummy class
DEMO
1. Extract protocol
2. Use protocol injection
3. Dummy class

15. Dummy class
// LCWire.h
@protocol Expirable <NSObject>
- (BOOL)isExpired;
@end
@interface LCWire : NSObject <Expirable>
- (BOOL)isExpired;
@end
// LCRoomTests.m
// 永遠不會過期的電線
@interface LCNeverExpiredWire : NSObject <Expirable>
@end
@implementation LCNeverExpiredWire
- (BOOL)isExpired {
return NO;
}
@end
@interface LCRoomTests : XCTestCase
@end
@implementation LCRoomTests
- (void)testLightOnInit
{
id<Expirable> wire = [[LCNeverExpiredWire alloc] init];
LCRoom *room = [[LCRoom alloc] initWithLight:YES wire:wire];
XCTAssertTrue(room.isLight);
}
@end

16. Dummy class
- (void)testLightOnInit
{
LCWire *wire = [[LCWire alloc] init];
LCRoom *room = [[LCRoom alloc] initWithLight:YES wire:wire];
XCTAssertTrue(room.isLight);
}
- (void)testLightOnInit
{
id<Expirable> wire = [[LCNeverExpiredWire alloc] init];
LCRoom *room = [[LCRoom alloc] initWithLight:YES wire:wire];
XCTAssertTrue(room.isLight);
}

17. Dummy class

18. Break dependency
那那些不能透過軟體設
計控制的怎麼辦?

19. Break dependency
Mock
OCMock

20. Mock object

21. Mock - PartialMock()
- (void)testLightOnInit
{
// Mock ⼀一個永遠不會過期的電線
LCWire *wire = [[LCWire alloc] init];
id mockWire = OCMPartialMock(wire);
OCMStub([mockWire isExpired]).andReturn(NO);
LCRoom *room = [[LCRoom alloc] initWithLight:YES wire:wire];
XCTAssertTrue(room.isLight);
}

22. Mock
1. Mock [NSDate date]
2. Mock [NSUserDefault standardDefault]
3. Mock session
4. Mock different user in a test case

23. Mock singleton
- (void)testMockDate
{
NSDate *now = [NSDate date];
NSDateComponents *comps = [[NSDateComponents alloc] init];
[comps setDay:10];
[comps setMonth:10];
[comps setYear:2010];
NSDate *speficDate = [[NSCalendar currentCalendar] dateFromComponents:comps];
id mockDate = OCMClassMock([NSDate class]);
OCMStub([mockDate date]).andReturn(speficDate);
// Mock [NSDate date] 讓他回傳指定⽇日期, 也就是 Mock 現在時間
NSLog(@"now: %@, mockDate: %@",now, [NSDate date]);
}
- (void)testMockUserdefault
{
NSString *name = [[NSUserDefaults standardUserDefaults] objectForKey:@"userName"];
id mockUserDefault = OCMPartialMock([NSUserDefaults standardUserDefaults]);
OCMStub([mockUserDefault objectForKey:@"userName"]).andReturn(@"Liyao Chen");
NSString *mockName = [[NSUserDefaults standardUserDefaults]
objectForKey:@"userName"];
NSLog(@"name: %@, mockName: %@", name, mockName);
}

24. Summary
• 發現程式缺陷才能解決
• 善⽤用依賴注⼊入改善程式架構
• 當測試有多個Mock時重新檢視設計

25. QnA
• API測試不是後端的⼯工作嗎?
• 什麼東⻄西⼀一定要測?

26. We are hiring!
@ KKBOX

27. Reference
• http://stackoverflow.com/questions/346372/
whats-the-difference-between-faking-mocking-
and-stubbing

28. Other links
• Sample code
https://github.com/gliyao/LCUnitTestsExample