This document outlines the 7 stages of unit testing: 1) Shock & Disbelief, 2) Denial, 3) Anger, 4) Bargain, 5) Guilt, 6) Depression, 7) Acceptance & Hope. It provides examples of different types of unit tests like testing return values, state changes, and behaviors using stubs, mocks and dependency injection. It also discusses improving test quality by following rules, prioritizing coverage, and measuring it, as well as integrating other test types and using CI/CD as developers progress through the stages towards acceptance of unit testing.

1. 7 Stages of Unit
Testing in iOS
Jorge D. Ortiz-Fuentes
@jdortiz
#7SUnitTest

2. A Canonical
Examples
production
#7SUnitTest

3. #7SUnitTest
Agenda
Evangelize about unit tests to seasoned
programmers
Introduce them to everybody else

4. 1.

5. Shock & Disbelief

6. But my code is
always awesome!

7. #7SUnitTest
Unit Tests
Prove correctness of different aspects of the
public interface.
• Prove instead of intuition
• Define contract and assumptions
• Document the code
• Easier refactoring or change
Reusable code = code + tests

8. Test the parts
that you aren’t
developing now

9. #7SUnitTest
Use Unit Testing
Incrementally
You don’t have to write every unit test
Start with the classes that take care of the
logic
• If mixed apply SOLID
The easier entry point are bugs

10. 2.

11. Denial

12. C’mon, it takes
ages to write
tests!

13. Time writing tests <
Time debugging

14. #7SUnitTest
Good & Bad News
Most already available in Xcode / not doubles
Projects are created with
• test target
• a crappy example
⌘+U is your friend
Behaviors provide Pavlov reinforcement
XCTest is THE tool for the rest you are on your own

15. 3.

16. Anger

17. How do I write
those f***ing
tests?

18. #7SUnitTest
Types of Unit Tests
Test return value
Test state
Test behavior

19. #7SUnitTest
The SUT
@interface Thermostat : NSObject
@property (strong, nonatomic) NSNumber *setpoint;
@property (assign, nonatomic) BOOL imperialSystem;
- (NSString *) showSetpoint;
- (void) increaseSetpoint;
- (void) saveSetpoint;
@end

20. #7SUnitTest
Return
- (NSString *) showSetpoint {
return [NSString stringWithFormat:@"%@ %@", self.setpoint,
self.imperialSystem?@"F":@"C"];
}

21. #7SUnitTest
Test return
- (void) testSetpointIsShownWithTheRightUnits {
// Arrange
sut.setpoint = @23;
sut.imperialSystem = NO;
// Act
NSString *shownSetpoint = [sut showSetpoint];
// Assert
XCTAssertEqualObjects(shownSetpoint, @"23 C");
}

22. #7SUnitTest
State
- (void) increaseSetpoint {
self.setpoint = @([self.setpoint intValue] + 1);
}

23. #7SUnitTest
Test state
- (void) testIncreaseSetpointAddsOne {
// Arrange
sut.setpoint = @23;
// Act
[sut increaseSetpoint];
// Assert
XCTAssertEqualObjects(sut.setpoint, @24);
}

24. #7SUnitTest
Behavior
@interface Thermostat()
@property (strong, nonatomic) NSUserDefaults *userDefaults;
@end
@implementation Thermostat
- (void) saveSetpoint {
[self.userDefaults setObject:self.setpoint
forKey:@"setpoint"];
}
- (NSUserDefaults *) userDefaults {
if (_userDefaults == nil) {
_userDefaults = [NSUserDefaults standardUserDefaults];
}
return _userDefaults;
}
@end

25. #7SUnitTest
Create a Spy
@interface UserDefaultsMock: NSUserDefaults
@property (assign, nonatomic) BOOL valueWasSet;
@end
@implementation UserDefaultsMock
- (void)setValue:(id)value forKey:(NSString *)key {
self.valueWasSet = YES;
}
@end

26. #7SUnitTest
Test behavior
- (void) testSetpointIsPersisted {
// Arrange
sut.setpoint = @23;
UserDefaultsMock *userDefMock = [UserDefaultsMock new];
[sut setValue:userDefMock forKey:@"userDefaults"];
// Act
[sut saveSetpoint];
// Assert
XCTAssertTrue(userDefMock.valueWasSet);
}

27. 4.

28. Bargain

29. Ok, I’ll write
some tests, but
make my life
simpler

30. - (void) testSetpointIsPersisted {
// Arrange
sut.setpoint = @23;
id userDefMock = [OCMockObject mockForClass:[NSUserDefaults class]];
OCMExpect([userDefMock setObject:sut.setpoint forKey:@"setpoint"]);
[sut setValue:userDefMock forKey:@"userDefaults"];
// Act
[sut saveSetpoint];
// Assert
XCTAssertNoThrow([userDefMock verify]);
}
Simulating and Testing
Behavior
Stubs & Mocks
• Both are test doubles
• Stubs provide desired responses to the SUT
• Spies also expect certain behaviors
• Mocks include verification

31. #7SUnitTest
Use a Mocking
Framework
Install as a pod
• OCMock
• OCMockito
Not for Swift 😱

32. #7SUnitTest
Dependency Injection
Control behavior of the dependencies
• Constructor
• Method overwriting
• Property injection:Lazy instantiation
Or use a DI framework (uncommon)

33. #7SUnitTest
An Assertion Framework
Richer semantics
• OCHamcrest
• Expecta
• Nimble

34. 5.

35. Guilt

36. My tests are
never good
enough!

37. #7SUnitTest
Follow the rules
Test your code only
Only a level of abstraction
Only public methods
Only one assertion per test
Tests are independent of sequence or state

38. 6.

39. Depression

40. But my coverage
is poor

41. #7SUnitTest
Improve your coverage
Measure it
Assign priorities
Agree upon rules for your team/project

42. Coverage

43. Improve

44. #7SUnitTest
And when I have too
many tests?
Disable test cases
Run from command line
• xcodebuild
• xcpretty

45. 7.

46. Acceptance &
Hope

47. No tests, no fun

48. #7SUnitTest
Evolve
Clean Architecture
TDD
Other tests: integration, ui, performance…
CI (OSX Server / Jenkins)

49. Thank
you!

50. @jdortiz
#7SUnitTest