7 Stages of Unit Testing in iOS
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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.
![#7SUnitTest
Return
- (NSString *) showSetpoint {
return [NSString stringWithFormat:@"%@ %@", self.setpoint,
self.imperialSystem?@"F":@"C"];
}](https://image.slidesharecdn.com/7stagesofunittestingios-160505181214/85/7-Stages-of-Unit-Testing-in-iOS-20-320.jpg)
![#7SUnitTest
Test return
- (void) testSetpointIsShownWithTheRightUnits {
// Arrange
sut.setpoint = @23;
sut.imperialSystem = NO;
// Act
NSString *shownSetpoint = [sut showSetpoint];
// Assert
XCTAssertEqualObjects(shownSetpoint, @"23 C");
}](https://image.slidesharecdn.com/7stagesofunittestingios-160505181214/85/7-Stages-of-Unit-Testing-in-iOS-21-320.jpg)
![#7SUnitTest
State
- (void) increaseSetpoint {
self.setpoint = @([self.setpoint intValue] + 1);
}](https://image.slidesharecdn.com/7stagesofunittestingios-160505181214/85/7-Stages-of-Unit-Testing-in-iOS-22-320.jpg)
![#7SUnitTest
Test state
- (void) testIncreaseSetpointAddsOne {
// Arrange
sut.setpoint = @23;
// Act
[sut increaseSetpoint];
// Assert
XCTAssertEqualObjects(sut.setpoint, @24);
}](https://image.slidesharecdn.com/7stagesofunittestingios-160505181214/85/7-Stages-of-Unit-Testing-in-iOS-23-320.jpg)
![#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](https://image.slidesharecdn.com/7stagesofunittestingios-160505181214/85/7-Stages-of-Unit-Testing-in-iOS-24-320.jpg)
![#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);
}](https://image.slidesharecdn.com/7stagesofunittestingios-160505181214/85/7-Stages-of-Unit-Testing-in-iOS-26-320.jpg)
![- (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](https://image.slidesharecdn.com/7stagesofunittestingios-160505181214/85/7-Stages-of-Unit-Testing-in-iOS-30-320.jpg)
7 Stages of Unit Testing in iOS
- 1. 7 Stages of Unit Testing in iOS Jorge D. Ortiz-Fuentes @jdortiz #7SUnitTest
- 3. #7SUnitTest Agenda Evangelize about unit tests to seasoned programmers Introduce them to everybody else
- 4. 1.
- 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.
- 47. No tests, no fun
- 48. #7SUnitTest Evolve Clean Architecture TDD Other tests: integration, ui, performance… CI (OSX Server / Jenkins)
- 49. Thank you!