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iOS testing

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Tomasz Janeczko
Tomasz Janeczko

This document discusses testing in iOS applications. It begins by introducing the author and their background. It then discusses reasons for testing like reliability, regression testing, and confidence during refactoring. Potential issues with testing like heavy UI dependence and non-testable code are addressed. The document recommends separating UI and service code for better testability. It demonstrates the Kiwi and OCMock testing frameworks and provides examples of testing classes, dependencies, and private/static methods in an isolated way without heavy mocking. It emphasizes best practices like writing tests first and using version control properly.

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Testing in iOS 10.01.2013 by Tomasz Janeczko
About me Tomasz Janeczko ? iOS developer in Kainos ? Enthusiast of business, electronics, Rails & Heroku ? Organizer of ?rst App Camp in UK and PL
So let¡¯s talk about testing.
Why we test?
iOS testing
So?
? Reliability ? Regression ? Con?dence (e.g. refactoring)
Why not to test?
Why not to test? ? Heavy dependence on UI ? Non-testable code ? Bad framework
How to address issues ? Sample - downloading stuff from interwebz
First fault Writing tests after writing code
Separation of concerns
Separation of concerns ? Let¡¯s separate out the UI code ? Same for services interaction
Demo of tests
Writing tests Meet Kiwi and OCMock
Kiwi ? RSpec-like tests writing ? Matchers ? Cleaner and more self-descriptive code
Kiwi describe(@"Tested class", ^{ context(@"When created", ^{ it(@"should not fail", ^{ [[theValue(0) should] equal:theValue(0)]; }); }); });
Kiwi describe(@"Tested class", ^{ context(@"When created", ^{ it(@"should not fail", ^{ id viewController = [ViewController new]; [[viewController should] conformToProtocol:@protocol(UITableViewDelegate)]; }); }); });
Matchers [subject ?shouldNotBeNil] ? [subject ?shouldBeNil] ? [[subject ?should] ?beIdenticalTo:(id)anObject] - compares id's ? [[subject ?should] ?equal:(id)anObject] ? [[subject ?should] ?equal:(double)aValue ?withDelta: (double)aDelta] ? [[subject ?should] ?beWithin:(id)aDistance ?of:(id)aValue] ? [[subject ?should] ?beLessThan:(id)aValue] ? etc. ?etc.
Compare to SenTesting Kit [[subject ?should] ?equal:anObject] compare ?with STAssertEquals(subject, ?anObject, ?@¡±Should ?be ?equal¡±);
OCMock ? Mocking and stubbing library for iOS ? Quite versatile ? Makes use of NSProxy magic
Sample work?ows
Classic calculator sample describe(@"Calculator", ?^{ ? ? ? ? ? ? ? ?context(@"with ?the ?numbers ?60 ?and ?5 ?entered", ?^{ ? ? ? ? ? ? ? ?RPNCalculator ?*calculator ?= ?[[RPNCalculator ?alloc] ?init]; ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?beforeEach(^{ ? ? ? ? ? ? ? ? ? ? ? ?[calculator ?enter:60]; ? ? ? ? ? ? ? ? ? ? ? ?[calculator ?enter:5]; ? ? ? ? ? ? ? ?}); ? ? ? ? ? ? ? ?afterEach(^{ ? ? ? ? ? ? ? ? ? ? ? ? ?[calculator ?clear]; ? ? ? ? ? ? ? ?}); ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?it(@"returns ?65 ?as ?the ?sum", ?^{ ? ? ? ? ? ? ? ? ? ? ? ?[[theValue([calculator ?add]) ?should] ?equal:65 ?withDelta:.01]; ? ? ? ? ? ? ? ?});
Test if calls dep methods 1. Create a mock dependency 2. Inject it 3. Call the method 4. Verify
Test dependency // Create the tested object and mock to exchange part of the functionality viewController = [ViewController new]; mockController = [OCMockObject partialMockForObject:viewController]; // Create the mock and change implementation to return our class id serviceMock = [OCMockObject mockForClass:[InterwebzService class]]; [[[mockController stub] andReturn:serviceMock] service]; // Define expectations [[serviceMock expect] downloadTweetsJSONWithSuccessBlock:[OCMArg any]]; // Run the tested method [viewController tweetsButtonTapped:nil]; // Verify - throws exception on failure [mockController verify];
Testing one layer ? Isolate dependencies ? Objective-C is highly dynamic - we can change implementations of private methods or static methods ? We can avoid IoC containers for testing
Accessing private methods
Accessing private methods @interface ViewController() - (void)startDownloadingTweets; @end ... [[mockController expect] startDownloadingTweets];
Static method testing ? Through separation to a method @interface ViewController() - (NSUserDefaults *)userDefaults; @end ... id mockDefaults = [OCMockObject mockForClass:[NSUserDefaults class]]; [[[mockDefaults expect] andReturn:@"Setting"] valueForKey:[OCMArg any]]; [[[mockController stub] andReturn:mockDefaults] userDefaults];
Static method testing ? Through method swizzling void ?SwizzleClassMethod(Class ?c, ?SEL ?orig, ?SEL ?new) ?{ ? ? ? ?Method ?origMethod ?= ?class_getClassMethod(c, ?orig); ? ? ? ?Method ?newMethod ?= ?class_getClassMethod(c, ?new); ? ? ? ?c ?= ?object_getClass((id)c); ? ? ? ?if(class_addMethod(c, ?orig, ?method_getImplementation(newMethod), ?method_getTypeEncoding(newMethod))) ? ? ? ? ? ? ? ?class_replaceMethod(c, ?new, ?method_getImplementation(origMethod), ? method_getTypeEncoding(origMethod)); ? ? ? ?else ? ? ? ? ? ? ? ?method_exchangeImplementations(origMethod, ?newMethod); }
Normal conditions apply despite it¡¯s iOS & Objective--C
Problems of ?mobile devs¡± ? Pushing code with failing tests ? Lot¡¯s of hacking together ? Weak knowledge of VCS tools - merge nightmares
Ending thoughts ? Think ?rst (twice), then code :) ? Tests should come ?rst ? Write the failing test, pass the test, refactor ? Adequate tools can enhance your testing experience
Ending thoughts ? Practice!
Thanks!
Questions

More Related Content

iOS testing

  • 1. Testing in iOS 10.01.2013 by Tomasz Janeczko
  • 2. About me Tomasz Janeczko ? iOS developer in Kainos ? Enthusiast of business, electronics, Rails & Heroku ? Organizer of ?rst App Camp in UK and PL
  • 3. So let¡¯s talk about testing.
  • 6. So?
  • 7. ? Reliability ? Regression ? Con?dence (e.g. refactoring)
  • 8. Why not to test?
  • 9. Why not to test? ? Heavy dependence on UI ? Non-testable code ? Bad framework
  • 10. How to address issues ? Sample - downloading stuff from interwebz
  • 11. First fault Writing tests after writing code
  • 13. Separation of concerns ? Let¡¯s separate out the UI code ? Same for services interaction
  • 16. Kiwi ? RSpec-like tests writing ? Matchers ? Cleaner and more self-descriptive code
  • 17. Kiwi describe(@"Tested class", ^{ context(@"When created", ^{ it(@"should not fail", ^{ [[theValue(0) should] equal:theValue(0)]; }); }); });
  • 18. Kiwi describe(@"Tested class", ^{ context(@"When created", ^{ it(@"should not fail", ^{ id viewController = [ViewController new]; [[viewController should] conformToProtocol:@protocol(UITableViewDelegate)]; }); }); });
  • 19. Matchers [subject ?shouldNotBeNil] ? [subject ?shouldBeNil] ? [[subject ?should] ?beIdenticalTo:(id)anObject] - compares id's ? [[subject ?should] ?equal:(id)anObject] ? [[subject ?should] ?equal:(double)aValue ?withDelta: (double)aDelta] ? [[subject ?should] ?beWithin:(id)aDistance ?of:(id)aValue] ? [[subject ?should] ?beLessThan:(id)aValue] ? etc. ?etc.
  • 20. Compare to SenTesting Kit [[subject ?should] ?equal:anObject] compare ?with STAssertEquals(subject, ?anObject, ?@¡±Should ?be ?equal¡±);
  • 21. OCMock ? Mocking and stubbing library for iOS ? Quite versatile ? Makes use of NSProxy magic
  • 23. Classic calculator sample describe(@"Calculator", ?^{ ? ? ? ? ? ? ? ?context(@"with ?the ?numbers ?60 ?and ?5 ?entered", ?^{ ? ? ? ? ? ? ? ?RPNCalculator ?*calculator ?= ?[[RPNCalculator ?alloc] ?init]; ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?beforeEach(^{ ? ? ? ? ? ? ? ? ? ? ? ?[calculator ?enter:60]; ? ? ? ? ? ? ? ? ? ? ? ?[calculator ?enter:5]; ? ? ? ? ? ? ? ?}); ? ? ? ? ? ? ? ?afterEach(^{ ? ? ? ? ? ? ? ? ? ? ? ? ?[calculator ?clear]; ? ? ? ? ? ? ? ?}); ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?it(@"returns ?65 ?as ?the ?sum", ?^{ ? ? ? ? ? ? ? ? ? ? ? ?[[theValue([calculator ?add]) ?should] ?equal:65 ?withDelta:.01]; ? ? ? ? ? ? ? ?});
  • 24. Test if calls dep methods 1. Create a mock dependency 2. Inject it 3. Call the method 4. Verify
  • 25. Test dependency // Create the tested object and mock to exchange part of the functionality viewController = [ViewController new]; mockController = [OCMockObject partialMockForObject:viewController]; // Create the mock and change implementation to return our class id serviceMock = [OCMockObject mockForClass:[InterwebzService class]]; [[[mockController stub] andReturn:serviceMock] service]; // Define expectations [[serviceMock expect] downloadTweetsJSONWithSuccessBlock:[OCMArg any]]; // Run the tested method [viewController tweetsButtonTapped:nil]; // Verify - throws exception on failure [mockController verify];
  • 26. Testing one layer ? Isolate dependencies ? Objective-C is highly dynamic - we can change implementations of private methods or static methods ? We can avoid IoC containers for testing
  • 28. Accessing private methods @interface ViewController() - (void)startDownloadingTweets; @end ... [[mockController expect] startDownloadingTweets];
  • 29. Static method testing ? Through separation to a method @interface ViewController() - (NSUserDefaults *)userDefaults; @end ... id mockDefaults = [OCMockObject mockForClass:[NSUserDefaults class]]; [[[mockDefaults expect] andReturn:@"Setting"] valueForKey:[OCMArg any]]; [[[mockController stub] andReturn:mockDefaults] userDefaults];
  • 30. Static method testing ? Through method swizzling void ?SwizzleClassMethod(Class ?c, ?SEL ?orig, ?SEL ?new) ?{ ? ? ? ?Method ?origMethod ?= ?class_getClassMethod(c, ?orig); ? ? ? ?Method ?newMethod ?= ?class_getClassMethod(c, ?new); ? ? ? ?c ?= ?object_getClass((id)c); ? ? ? ?if(class_addMethod(c, ?orig, ?method_getImplementation(newMethod), ?method_getTypeEncoding(newMethod))) ? ? ? ? ? ? ? ?class_replaceMethod(c, ?new, ?method_getImplementation(origMethod), ? method_getTypeEncoding(origMethod)); ? ? ? ?else ? ? ? ? ? ? ? ?method_exchangeImplementations(origMethod, ?newMethod); }
  • 31. Normal conditions apply despite it¡¯s iOS & Objective--C
  • 32. Problems of ?mobile devs¡± ? Pushing code with failing tests ? Lot¡¯s of hacking together ? Weak knowledge of VCS tools - merge nightmares
  • 33. Ending thoughts ? Think ?rst (twice), then code :) ? Tests should come ?rst ? Write the failing test, pass the test, refactor ? Adequate tools can enhance your testing experience