Luis Solano's Slides at NSSpain 2013

NSSpain is an iOS & OSX developers conference in Spain.
More info: http://nsspain.com

Transcript

1. Consuming Web APIs, the TDD way Luis Solano @luisobo My name is Luis Solano I work at Pixable, a startup based in NYC leading the iOS team. You can find me on twitter and github. My handler is “luisobo”
2. Good practices for networking code - How to make it more maintainable - Unlike most material on TDD, which only covers basic examples. - Principles that you can apply to any scenario in test-driven development.
3. Good practices for networking code Tackle real life testing scenarios - How to make it more maintainable - Unlike most material on TDD, which only covers basic examples. - Principles that you can apply to any scenario in test-driven development.
4. Good practices for networking code Tackle real life testing scenarios Underlaying principles of TDD - How to make it more maintainable - Unlike most material on TDD, which only covers basic examples. - Principles that you can apply to any scenario in test-driven development.
5. Good practices for networking code Tackle real life testing scenarios Underlaying principles of TDD Better user experience - How to make it more maintainable - Unlike most material on TDD, which only covers basic examples. - Principles that you can apply to any scenario in test-driven development.
6. - Less loading time for our users - Less errors and more meaningful ones. - Potentially less app updates
7. - Less loading time for our users - Less errors and more meaningful ones. - Potentially less app updates
8. - Less loading time for our users - Less errors and more meaningful ones. - Potentially less app updates
9. API Client design - Let’s talk about some ideas that our API clients sound embrace
10. Abstraction Wrapper
11. Forward compatibility - Ability for the API to evolve without breaking existing clients - Consumers of the API enable this.
12. { "user": { "firstName": "John", "lastName": "Appleseed", "city": "Valencia" // ... } }
13. @interface LSBUser : NSObject @property (nonatomic, strong) NSString *firstName; @property (nonatomic, strong) NSString *lastName; @property (nonatomic, strong) NSString *city; // ... @end
14. LSBUser *user = [[LSBUser alloc] init]; for (NSString *key in JSON) { [user setValue:JSON[key] forKey:key]; }
15. { "user": { "firstName": "John", "lastName": "Appleseed", "city": "Valencia", // ... } } "newField": "something"
16. NSUnknownKeyException "[<LSBUser 0x75837a0> setValueɿ forUndefinedKeyɿ]ɿ this class is not key value coding-compliant for the key newField." raised
17. if (response.statusCode == 200) { // ... }
18. if (response.statusCode >= 200 && response.statusCode < 300) { // ... }
19. Avoid forging URLs in the client
20. { "post":{ "links":[{ "rel":"self", "href":"http://blog/post/4711" },{ "rel":"author", "href":"http://author/uri" }], "title":"foobar", "content":"A long article here…" } }
21. [request setValue:@"My Awesome Client (1.2.3)" forHTTPHeaderField:@"User-Agent"];
23. require 'sinatra' require 'json' get "/dogs.json" do content_type :json { dogs: [{ name: "perro", color: "brown" },{ name: "tomas", color: "black" }] }.to_json end
24. Our first test Because we do TDD. YEAH!
25. it(@"retrieves dogs", ^{ });
26. it(@"retrieves dogs", ^{ }); [[LSBDogCare new] allDogs:^(NSArray *dogs) { } failure:^(NSError *error) { }];
27. it(@"retrieves dogs", ^{ }); [[LSBDogCare new] allDogs:^(NSArray *dogs) { } failure:^(NSError *error) { }]; __block NSArray *capturedDogs = nil; capturedDogs = dogs;
28. it(@"retrieves dogs", ^{ }); [[LSBDogCare new] allDogs:^(NSArray *dogs) { } failure:^(NSError *error) { }]; [[expectFutureValue(capturedDogs) shouldEventually] equal:@[@{@"name":@"perro",@"color":@"brown"}, @{@"name":@"tomas",@"color":@"black"} ]]; __block NSArray *capturedDogs = nil; capturedDogs = dogs;
29. it(@"retrieves dogs", ^{ }); [[LSBDogCare new] allDogs:^(NSArray *dogs) { } failure:^(NSError *error) { }]; [[expectFutureValue(capturedDogs) shouldEventually] equal:@[@{@"name":@"perro",@"color":@"brown"}, @{@"name":@"tomas",@"color":@"black"} ]]; __block NSArray *capturedDogs = nil; capturedDogs = dogs;
30. @implementation LSBDogCare - (void)allDogs:(void(^)(NSArray *dogs))success failure:(void(^)(NSError *error))failure { } @end
31. @implementation LSBDogCare - (void)allDogs:(void(^)(NSArray *dogs))success failure:(void(^)(NSError *error))failure { } @end NSURL *url = [NSURL URLWithString:@"http://localhost:4567/dogs.json"]; NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
32. @implementation LSBDogCare - (void)allDogs:(void(^)(NSArray *dogs))success failure:(void(^)(NSError *error))failure { } @end NSURL *url = [NSURL URLWithString:@"http://localhost:4567/dogs.json"]; NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url]; AFJSONRequestOperation *op; op = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, NSDictionary *JSON) { } failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *requestError, id JSON) { }];
33. @implementation LSBDogCare - (void)allDogs:(void(^)(NSArray *dogs))success failure:(void(^)(NSError *error))failure { } @end NSURL *url = [NSURL URLWithString:@"http://localhost:4567/dogs.json"]; NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url]; AFJSONRequestOperation *op; op = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, NSDictionary *JSON) { } failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *requestError, id JSON) { }]; success(JSON[@"dogs"]);
34. @implementation LSBDogCare - (void)allDogs:(void(^)(NSArray *dogs))success failure:(void(^)(NSError *error))failure { } @end NSURL *url = [NSURL URLWithString:@"http://localhost:4567/dogs.json"]; NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url]; AFJSONRequestOperation *op; op = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, NSDictionary *JSON) { } failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *requestError, id JSON) { }]; success(JSON[@"dogs"]); [op start];
35. @implementation LSBDogCare - (void)allDogs:(void(^)(NSArray *dogs))success failure:(void(^)(NSError *error))failure { } @end NSURL *url = [NSURL URLWithString:@"http://localhost:4567/dogs.json"]; NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url]; AFJSONRequestOperation *op; op = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, NSDictionary *JSON) { } failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *requestError, id JSON) { }]; success(JSON[@"dogs"]); [op start];
36. it(@"retrieves dogs", ^{ __block NSArray *capturedDogs = nil; [[LSBDogCare new] allDogs:^(NSArray *dogs) { capturedDogs = dogs; } failure:^(NSError *error) { }]; [[expectFutureValue(capturedDogs) shouldEventually] equal:@[@{@"name":@"perro",@"color":@"brown"}, @{@"name":@"tomas",@"color":@"black"} ]]; }); BAM! We have our first test Raise you hand if you see any problems with this test What is wrong with it? It’s hitting the real network: undeterministic, slow dependency Real life test case Principle TDD: isolate code from undeterministic and slow depencencies.
37. Isolate tests from undeterministic and slow depencencies. This applies to databases, file system, global state, etc
38. it(@"retrieves dogs", ^{ __block NSArray *capturedDogs = nil; [[LSBDogCare new] allDogs:^(NSArray *dogs) { capturedDogs = dogs; } failure:^(NSError *error) { }]; [[expectFutureValue(capturedDogs) shouldEventually] equal:@[@{@"name":@"perro",@"color":@"brown"}]]; }); BAM! No network! No it’s deterministic, and fast. Raise you hand if you see any problems with this test. What is wrong with it?
39. it(@"retrieves dogs", ^{ __block NSArray *capturedDogs = nil; [[LSBDogCare new] allDogs:^(NSArray *dogs) { capturedDogs = dogs; } failure:^(NSError *error) { }]; [[expectFutureValue(capturedDogs) shouldEventually] equal:@[@{@"name":@"perro",@"color":@"brown"}]]; }); AFJSONRequestOperation *mockOp = [AFJSONRequestOperation mock]; BAM! No network! No it’s deterministic, and fast. Raise you hand if you see any problems with this test. What is wrong with it?
40. it(@"retrieves dogs", ^{ __block NSArray *capturedDogs = nil; [[LSBDogCare new] allDogs:^(NSArray *dogs) { capturedDogs = dogs; } failure:^(NSError *error) { }]; [[expectFutureValue(capturedDogs) shouldEventually] equal:@[@{@"name":@"perro",@"color":@"brown"}]]; }); AFJSONRequestOperation *mockOp = [AFJSONRequestOperation mock]; [AFJSONRequestOperation stub:@selector(JSONRequestOperationWithRequest:success:failure:) withBlock:^id(NSArray *params) { return mockOp; }]; BAM! No network! No it’s deterministic, and fast. Raise you hand if you see any problems with this test. What is wrong with it?
41. it(@"retrieves dogs", ^{ __block NSArray *capturedDogs = nil; [[LSBDogCare new] allDogs:^(NSArray *dogs) { capturedDogs = dogs; } failure:^(NSError *error) { }]; [[expectFutureValue(capturedDogs) shouldEventually] equal:@[@{@"name":@"perro",@"color":@"brown"}]]; }); AFJSONRequestOperation *mockOp = [AFJSONRequestOperation mock]; [AFJSONRequestOperation stub:@selector(JSONRequestOperationWithRequest:success:failure:) withBlock:^id(NSArray *params) { return mockOp; }]; __block NSURLRequest *capturedRequest; __block void (^capturedSuccess)(NSURLRequest *request, NSHTTPURLResponse *response, id JSON); BAM! No network! No it’s deterministic, and fast. Raise you hand if you see any problems with this test. What is wrong with it?
42. it(@"retrieves dogs", ^{ __block NSArray *capturedDogs = nil; [[LSBDogCare new] allDogs:^(NSArray *dogs) { capturedDogs = dogs; } failure:^(NSError *error) { }]; [[expectFutureValue(capturedDogs) shouldEventually] equal:@[@{@"name":@"perro",@"color":@"brown"}]]; }); AFJSONRequestOperation *mockOp = [AFJSONRequestOperation mock]; [AFJSONRequestOperation stub:@selector(JSONRequestOperationWithRequest:success:failure:) withBlock:^id(NSArray *params) { return mockOp; }]; __block NSURLRequest *capturedRequest; __block void (^capturedSuccess)(NSURLRequest *request, NSHTTPURLResponse *response, id JSON); capturedRequest = params[0]; capturedSuccess = params[1]; BAM! No network! No it’s deterministic, and fast. Raise you hand if you see any problems with this test. What is wrong with it?
43. it(@"retrieves dogs", ^{ __block NSArray *capturedDogs = nil; [[LSBDogCare new] allDogs:^(NSArray *dogs) { capturedDogs = dogs; } failure:^(NSError *error) { }]; [[expectFutureValue(capturedDogs) shouldEventually] equal:@[@{@"name":@"perro",@"color":@"brown"}]]; }); AFJSONRequestOperation *mockOp = [AFJSONRequestOperation mock]; [AFJSONRequestOperation stub:@selector(JSONRequestOperationWithRequest:success:failure:) withBlock:^id(NSArray *params) { return mockOp; }]; [mockOp stub:@selector(start) withBlock:^id(NSArray *params) { capturedSuccess(capturedRequest, [NSHTTPURLResponse mock], @{@"dogs":@[@{@"name":@"perro",@"color":@"brown"}]}); return nil; }]; __block NSURLRequest *capturedRequest; __block void (^capturedSuccess)(NSURLRequest *request, NSHTTPURLResponse *response, id JSON); capturedRequest = params[0]; capturedSuccess = params[1]; BAM! No network! No it’s deterministic, and fast. Raise you hand if you see any problems with this test. What is wrong with it?
44. it(@"retrieves dogs", ^{ __block NSArray *capturedDogs = nil; [[LSBDogCare new] allDogs:^(NSArray *dogs) { capturedDogs = dogs; } failure:^(NSError *error) { }]; [[expectFutureValue(capturedDogs) shouldEventually] equal:@[@{@"name":@"perro",@"color":@"brown"}]]; }); AFJSONRequestOperation *mockOp = [AFJSONRequestOperation mock]; [AFJSONRequestOperation stub:@selector(JSONRequestOperationWithRequest:success:failure:) withBlock:^id(NSArray *params) { return mockOp; }]; [mockOp stub:@selector(start) withBlock:^id(NSArray *params) { capturedSuccess(capturedRequest, [NSHTTPURLResponse mock], @{@"dogs":@[@{@"name":@"perro",@"color":@"brown"}]}); return nil; }]; __block NSURLRequest *capturedRequest; __block void (^capturedSuccess)(NSURLRequest *request, NSHTTPURLResponse *response, id JSON); capturedRequest = params[0]; capturedSuccess = params[1]; BAM! No network! No it’s deterministic, and fast. Raise you hand if you see any problems with this test. What is wrong with it?
46. it(@"retrieves dogs", ^{ __block NSArray *capturedDogs = nil; [[LSBDogCare new] allDogs:^(NSArray *dogs) { capturedDogs = dogs; } failure:^(NSError *error) { }]; [[expectFutureValue(capturedDogs) shouldEventually] equal:@[@{@"name":@"perro",@"color":@"brown"}]]; }); AFJSONRequestOperation *mockOp = [AFJSONRequestOperation mock]; [AFJSONRequestOperation stub:@selector(JSONRequestOperationWithRequest:success:failure:) withBlock:^id(NSArray *params) { return mockOp; }]; [mockOp stub:@selector(start) withBlock:^id(NSArray *params) { capturedSuccess(capturedRequest, [NSHTTPURLResponse mock], @{@"dogs":@[@{@"name":@"perro",@"color":@"brown"}]}); return nil; }]; __block NSURLRequest *capturedRequest; __block void (^capturedSuccess)(NSURLRequest *request, NSHTTPURLResponse *response, id JSON); capturedRequest = params[0]; capturedSuccess = params[1]; The problem is that the test it’s coupled with the implementation details. Let’s see what’s wrong with that.
47. Test What my coworkers think I do Ideal TDD flow.
48. Test Implementation What my coworkers think I do Ideal TDD flow.
49. Test Implementation Refactor What my coworkers think I do Ideal TDD flow.
50. Test Implementation What I actually do What actually happens Definition of refactoring.
51. Test Implementation Refactor What I actually do What actually happens Definition of refactoring.
52. Test Implementation Refactor Change a test What I actually do What actually happens Definition of refactoring.
53. Test Implementation Refactor Change a test Change implementation What I actually do What actually happens Definition of refactoring.
54. Test Implementation Refactor Change a test Change implementation Shit I forgot to stub that What I actually do What actually happens Definition of refactoring.
55. $ git reset --hard
56. Don’t modify test and implementation at the same time
57. it(@"retrieves dogs", ^{ __block NSArray *capturedDogs = nil; [[LSBDogCare new] allDogs:^(NSArray *dogs) { capturedDogs = dogs; } failure:^(NSError *error) { }]; [[expectFutureValue(capturedDogs) shouldEventually] equal:@[@{@"name":@"perro",@"color":@"brown"}]]; }); AFJSONRequestOperation *mockOp = [AFJSONRequestOperation mock]; [AFJSONRequestOperation stub:@selector(JSONRequestOperationWithRequest:success:failure:) withBlock:^id(NSArray *params) { return mockOp; }]; [mockOp stub:@selector(start) withBlock:^id(NSArray *params) { capturedSuccess(capturedRequest, [NSHTTPURLResponse mock], @{@"dogs":@[@{@"name":@"perro",@"color":@"brown"}]}); return nil; }]; __block NSURLRequest *capturedRequest; __block void (^capturedSuccess)(NSURLRequest *request, NSHTTPURLResponse *response, id JSON); capturedRequest = params[0]; capturedSuccess = params[1]; Then, how can we test this?
59. it(@"retrieves dogs", ^{ __block NSArray *capturedDogs = nil; [[LSBDogCare new] allDogs:^(NSArray *dogs) { capturedDogs = dogs; } failure:^(NSError *error) { }]; [[expectFutureValue(capturedDogs) shouldEventually] equal:@[@{@"name":@"perro",@"color":@"brown"}, @{@"name":@"tomas",@"color":@"black"}]]; });
60. it(@"retrieves dogs", ^{ __block NSArray *capturedDogs = nil; [[LSBDogCare new] allDogs:^(NSArray *dogs) { capturedDogs = dogs; } failure:^(NSError *error) { }]; [[expectFutureValue(capturedDogs) shouldEventually] equal:@[@{@"name":@"perro",@"color":@"brown"}, @{@"name":@"tomas",@"color":@"black"}]]; }); stubRequest(@"GET", @"http://localhost:4567/dogs.json")
61. it(@"retrieves dogs", ^{ __block NSArray *capturedDogs = nil; [[LSBDogCare new] allDogs:^(NSArray *dogs) { capturedDogs = dogs; } failure:^(NSError *error) { }]; [[expectFutureValue(capturedDogs) shouldEventually] equal:@[@{@"name":@"perro",@"color":@"brown"}, @{@"name":@"tomas",@"color":@"black"}]]; }); stubRequest(@"GET", @"http://localhost:4567/dogs.json") .andReturn(200)
62. it(@"retrieves dogs", ^{ __block NSArray *capturedDogs = nil; [[LSBDogCare new] allDogs:^(NSArray *dogs) { capturedDogs = dogs; } failure:^(NSError *error) { }]; [[expectFutureValue(capturedDogs) shouldEventually] equal:@[@{@"name":@"perro",@"color":@"brown"}, @{@"name":@"tomas",@"color":@"black"}]]; }); stubRequest(@"GET", @"http://localhost:4567/dogs.json") .andReturn(200) .withHeaders(@{ @"Content-Type": @"application/json;charset=utf-8" })
63. it(@"retrieves dogs", ^{ __block NSArray *capturedDogs = nil; [[LSBDogCare new] allDogs:^(NSArray *dogs) { capturedDogs = dogs; } failure:^(NSError *error) { }]; [[expectFutureValue(capturedDogs) shouldEventually] equal:@[@{@"name":@"perro",@"color":@"brown"}, @{@"name":@"tomas",@"color":@"black"}]]; }); stubRequest(@"GET", @"http://localhost:4567/dogs.json") .andReturn(200) .withHeaders(@{ @"Content-Type": @"application/json;charset=utf-8" }) .withBody([@{@"dogs":@[ @{@"name":@"perro",@"color":@"brown"}, @{@"name":@"tomas",@"color":@"black"}] } JSONString]);
64. it(@"retrieves dogs", ^{ __block NSArray *capturedDogs = nil; [[LSBDogCare new] allDogs:^(NSArray *dogs) { capturedDogs = dogs; } failure:^(NSError *error) { }]; [[expectFutureValue(capturedDogs) shouldEventually] equal:@[@{@"name":@"perro",@"color":@"brown"}, @{@"name":@"tomas",@"color":@"black"}]]; }); stubRequest(@"GET", @"http://localhost:4567/dogs.json") .andReturn(200) .withHeaders(@{ @"Content-Type": @"application/json;charset=utf-8" }) .withBody([@{@"dogs":@[ @{@"name":@"perro",@"color":@"brown"}, @{@"name":@"tomas",@"color":@"black"}] } JSONString]);
65. Don’t couple test with implementation details Don’t test private methods Test external behavior of your modules Otherwise you will live in a tested trap. You won’t be able to leverage your tests to refactor.
66. context(@"when retrieving dogs fail because access was revoked", ^{ it(@"reports an error", ^{ }); });
67. context(@"when retrieving dogs fail because access was revoked", ^{ it(@"reports an error", ^{ }); }); __block NSError *capturedError; [[LSBDogCare new] allDogs:^(NSArray *dogs) { } failure:^(NSError *error) { capturedError = error; }];
68. context(@"when retrieving dogs fail because access was revoked", ^{ it(@"reports an error", ^{ }); }); __block NSError *capturedError; [[LSBDogCare new] allDogs:^(NSArray *dogs) { } failure:^(NSError *error) { capturedError = error; }]; [[expectFutureValue(capturedError) shouldEventually] equal:[NSError errorWithDomain:@"com.luisobo.dogcare" code:23 userInfo:@{ NSLocalizedDescriptionKey: @"uh uh uh, you didn't say the magic word" }]];
69. context(@"when retrieving dogs fail because access was revoked", ^{ it(@"reports an error", ^{ }); }); __block NSError *capturedError; [[LSBDogCare new] allDogs:^(NSArray *dogs) { } failure:^(NSError *error) { capturedError = error; }]; [[expectFutureValue(capturedError) shouldEventually] equal:[NSError errorWithDomain:@"com.luisobo.dogcare" code:23 userInfo:@{ NSLocalizedDescriptionKey: @"uh uh uh, you didn't say the magic word" }]]; stubRequest(@"GET", @"http://localhost:4567/dogs.json") .andReturn(401);
70. context(@"when retrieving dogs fail because access was revoked", ^{ it(@"reports an error", ^{ }); }); __block NSError *capturedError; [[LSBDogCare new] allDogs:^(NSArray *dogs) { } failure:^(NSError *error) { capturedError = error; }]; [[expectFutureValue(capturedError) shouldEventually] equal:[NSError errorWithDomain:@"com.luisobo.dogcare" code:23 userInfo:@{ NSLocalizedDescriptionKey: @"uh uh uh, you didn't say the magic word" }]]; stubRequest(@"GET", @"http://localhost:4567/dogs.json") .andReturn(401);
71. - (void)allDogs:(void(^)(NSArray *dogs))success failure:(void(^)(NSError *error))failure { // ... op = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, NSDictionary *JSON) { success(JSON[@"dogs"]); } failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) { }]; [op start]; }
72. - (void)allDogs:(void(^)(NSArray *dogs))success failure:(void(^)(NSError *error))failure { // ... op = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, NSDictionary *JSON) { success(JSON[@"dogs"]); } failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) { }]; [op start]; } if (response.statusCode == 401) { error = [NSError errorWithDomain:@"com.luisobo.dogcare" code:23 userInfo:@{ NSLocalizedDescriptionKey: @"uh uh uh, you didn't say the magic word" }]; } failure(error);
73. - (void)allDogs:(void(^)(NSArray *dogs))success failure:(void(^)(NSError *error))failure { // ... op = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, NSDictionary *JSON) { success(JSON[@"dogs"]); } failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) { }]; [op start]; } if (response.statusCode == 401) { error = [NSError errorWithDomain:@"com.luisobo.dogcare" code:23 userInfo:@{ NSLocalizedDescriptionKey: @"uh uh uh, you didn't say the magic word" }]; } failure(error);
74. context(@"when the request fails because there is no internet", ^{ it(@"reports an error", ^{ }); });
75. context(@"when the request fails because there is no internet", ^{ it(@"reports an error", ^{ }); }); __block NSError *capturedError; [[LSBDogCare new] allDogs:^(NSArray *dogs) { } failure:^(NSError *error) { capturedError = error; }];
76. context(@"when the request fails because there is no internet", ^{ it(@"reports an error", ^{ }); }); __block NSError *capturedError; [[LSBDogCare new] allDogs:^(NSArray *dogs) { } failure:^(NSError *error) { capturedError = error; }]; [[expectFutureValue(capturedError) shouldEventually] equal:[NSError errorWithDomain:@"com.luisobo.dogcare" code:446 userInfo:@{ NSLocalizedDescriptionKey: @"eeeer, check your internet dumbass" }]];
77. context(@"when the request fails because there is no internet", ^{ it(@"reports an error", ^{ }); }); __block NSError *capturedError; [[LSBDogCare new] allDogs:^(NSArray *dogs) { } failure:^(NSError *error) { capturedError = error; }]; [[expectFutureValue(capturedError) shouldEventually] equal:[NSError errorWithDomain:@"com.luisobo.dogcare" code:446 userInfo:@{ NSLocalizedDescriptionKey: @"eeeer, check your internet dumbass" }]]; stubRequest(@"GET", @"http://localhost:4567/dogs.json") .andFailWithError([NSError errorWithDomain:NSURLErrorDomain code:NSURLErrorCannotConnectToHost userInfo:nil]);
78. context(@"when the request fails because there is no internet", ^{ it(@"reports an error", ^{ }); }); __block NSError *capturedError; [[LSBDogCare new] allDogs:^(NSArray *dogs) { } failure:^(NSError *error) { capturedError = error; }]; [[expectFutureValue(capturedError) shouldEventually] equal:[NSError errorWithDomain:@"com.luisobo.dogcare" code:446 userInfo:@{ NSLocalizedDescriptionKey: @"eeeer, check your internet dumbass" }]]; stubRequest(@"GET", @"http://localhost:4567/dogs.json") .andFailWithError([NSError errorWithDomain:NSURLErrorDomain code:NSURLErrorCannotConnectToHost userInfo:nil]);
79. context(@"when the request fails because there is no internet", ^{ it(@"reports an error", ^{ }); }); __block NSError *capturedError; [[LSBDogCare new] allDogs:^(NSArray *dogs) { } failure:^(NSError *error) { capturedError = error; }]; [[expectFutureValue(capturedError) shouldEventually] equal:[NSError errorWithDomain:@"com.luisobo.dogcare" code:446 userInfo:@{ NSLocalizedDescriptionKey: @"eeeer, check your internet dumbass" }]]; stubRequest(@"GET", @"http://localhost:4567/dogs.json") .andFailWithError([NSError errorWithDomain:NSURLErrorDomain code:NSURLErrorCannotConnectToHost userInfo:nil]);
80. Released over a year ago. Regex ASIHTTPRequest: migrating
81. Test Nocilla enables proper TDD. It decouples tests from implementation.
82. Test Implementation Nocilla enables proper TDD. It decouples tests from implementation.
83. Test Implementation Refactor Nocilla enables proper TDD. It decouples tests from implementation.
84. https://github.com/luisobo/Nocilla Github CocoaPods Go get your copy Don’t forget to star it!
85. Error handling The operation could not be completed . (com.facebook.sdk error 2) Often neglected
86. 1. Developer screw-ups Developer mistake - Passed nil as an argument. - Fail fast and often - Beyond that point, the behavior is not defined. - Assert until it bleeds - Crash: BAM! IN YO FACE!
87. 1. Developer screw-ups 2. Everything else Developer mistake - Passed nil as an argument. - Fail fast and often - Beyond that point, the behavior is not defined. - Assert until it bleeds - Crash: BAM! IN YO FACE!
88. Group errors based on how the client is going to recover from them
93. 1. Automatic recoverable errors (e.g. reauthorize)
94. 1. Automatic recoverable errors (e.g. reauthorize) 2. User recoverable errors (e.g. validation, ask for more permissions)
95. 1. Automatic recoverable errors (e.g. reauthorize) 2. User recoverable errors (e.g. validation, ask for more permissions) 3. Known non-recoverable errors. (e.g. server is down, rate limiting)
96. 1. Automatic recoverable errors (e.g. reauthorize) 2. User recoverable errors (e.g. validation, ask for more permissions) 3. Known non-recoverable errors. (e.g. server is down, rate limiting) 4. “How the fu*k did I get here?” errors
97. NSError = domain + code Tuple to uniquely identify an error. Don’t check for error codes. You want to know how to react to an error Ask the error for the recovery strategy
98. NSUnderlyingErrorKey
100. @interface NSError (FacebookAPI) @end Let’s say that we are implementing the Facebook SDK used privately forms an error from a response
101. @interface NSError (FacebookAPI) @end + (instancetype)facebookAPIErrorWithResponse:(NSDictionary *)response; Let’s say that we are implementing the Facebook SDK used privately forms an error from a response
102. @interface NSError (FacebookAPI) @end + (instancetype)facebookAPIErrorWithResponse:(NSDictionary *)response; - (BOOL)isFacebookAPIError; Let’s say that we are implementing the Facebook SDK used privately forms an error from a response
103. @interface NSError (FacebookAPI) @end + (instancetype)facebookAPIErrorWithResponse:(NSDictionary *)response; - (BOOL)isFacebookAPIError; - (BOOL)shouldRecoverByReauthorizing; Let’s say that we are implementing the Facebook SDK used privately forms an error from a response
104. @interface NSError (FacebookAPI) @end + (instancetype)facebookAPIErrorWithResponse:(NSDictionary *)response; - (BOOL)isFacebookAPIError; - (BOOL)shouldRecoverByReauthorizing; - (BOOL)shouldRecoverByRequestingMorePermissions; Let’s say that we are implementing the Facebook SDK used privately forms an error from a response
105. @interface NSError (FacebookAPI) @end + (instancetype)facebookAPIErrorWithResponse:(NSDictionary *)response; - (BOOL)isFacebookAPIError; - (BOOL)shouldRecoverByReauthorizing; - (BOOL)shouldRecoverByRequestingMorePermissions; - (BOOL)shouldRecoverByNotifyingUser; Let’s say that we are implementing the Facebook SDK used privately forms an error from a response
106. failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) { } 1. Automatic recoverable errors (reauthorize) 2. User recoverable errors (validation)
107. failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) { } NSError *facebookError = [NSError facebookAPIErrorWithResponse:JSON]; 1. Automatic recoverable errors (reauthorize) 2. User recoverable errors (validation)
108. failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) { } NSError *facebookError = [NSError facebookAPIErrorWithResponse:JSON]; if ([facebookError shouldRecoverByReauthorizing]) { // Reauthorize } 1. Automatic recoverable errors (reauthorize) 2. User recoverable errors (validation)
109. failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) { } NSError *facebookError = [NSError facebookAPIErrorWithResponse:JSON]; if ([facebookError shouldRecoverByReauthorizing]) { // Reauthorize } else if ([facebookError shouldRecoverByRequestingMorePermissions]) { // Request more permissions } 1. Automatic recoverable errors (reauthorize) 2. User recoverable errors (validation)
110. failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) { } NSError *facebookError = [NSError facebookAPIErrorWithResponse:JSON]; if ([facebookError shouldRecoverByReauthorizing]) { // Reauthorize } else if ([facebookError shouldRecoverByRequestingMorePermissions]) { // Request more permissions } else if ([facebookError shouldRecoverByNotifyingUser]) { } 1. Automatic recoverable errors (reauthorize) 2. User recoverable errors (validation)
111. @interface NSError (FacebookSDK) + (instancetype)facebookSDKErrorWithError:(NSError *)error; - (BOOL)isFacebookSDKError; // ... Same deal @end Higher level of abstraction Different domain User friendly message Use NSUnderlayingErrorKey
112. failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) { } NSError *facebookError = [NSError facebookAPIErrorWithResponse:JSON]; if ([facebookError shouldRecoverByReauthorizing]) { // Reauthorize } else if ([facebookError shouldRecoverByRequestingMorePermissions]) { // Request more permissions } else if ([facebookError shouldRecoverByNotifyingUser]) { } 3. Known non-recoverable errors. (e.g. server is down, rate limiting) 4. “How the fu*k did I get here?” errors log remotely - alternative to crash reports TIME? More slides?
113. failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) { } NSError *facebookError = [NSError facebookAPIErrorWithResponse:JSON]; if ([facebookError shouldRecoverByReauthorizing]) { // Reauthorize } else if ([facebookError shouldRecoverByRequestingMorePermissions]) { // Request more permissions } else if ([facebookError shouldRecoverByNotifyingUser]) { } failure([NSError facebookSDKErrorWithError:error]); 3. Known non-recoverable errors. (e.g. server is down, rate limiting) 4. “How the fu*k did I get here?” errors log remotely - alternative to crash reports TIME? More slides?
114. failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) { } NSError *facebookError = [NSError facebookAPIErrorWithResponse:JSON]; if ([facebookError shouldRecoverByReauthorizing]) { // Reauthorize } else if ([facebookError shouldRecoverByRequestingMorePermissions]) { // Request more permissions } else if ([facebookError shouldRecoverByNotifyingUser]) { } else { failure([NSError genericError]); } failure([NSError facebookSDKErrorWithError:error]); 3. Known non-recoverable errors. (e.g. server is down, rate limiting) 4. “How the fu*k did I get here?” errors log remotely - alternative to crash reports TIME? More slides?
115. failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) { } NSError *facebookError = [NSError facebookAPIErrorWithResponse:JSON]; if ([facebookError shouldRecoverByReauthorizing]) { // Reauthorize } else if ([facebookError shouldRecoverByRequestingMorePermissions]) { // Request more permissions } else if ([facebookError shouldRecoverByNotifyingUser]) { } else { failure([NSError genericError]); } failure([NSError facebookSDKErrorWithError:error]); // Ensure consistent state 3. Known non-recoverable errors. (e.g. server is down, rate limiting) 4. “How the fu*k did I get here?” errors log remotely - alternative to crash reports TIME? More slides?
116. failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) { } NSError *facebookError = [NSError facebookAPIErrorWithResponse:JSON]; if ([facebookError shouldRecoverByReauthorizing]) { // Reauthorize } else if ([facebookError shouldRecoverByRequestingMorePermissions]) { // Request more permissions } else if ([facebookError shouldRecoverByNotifyingUser]) { } else { failure([NSError genericError]); } failure([NSError facebookSDKErrorWithError:error]); // Ensure consistent state // Log facebookError in a remote service 3. Known non-recoverable errors. (e.g. server is down, rate limiting) 4. “How the fu*k did I get here?” errors log remotely - alternative to crash reports TIME? More slides?
117. Charles Proxy charlesproxy.com
118. Nocilla
119. Integration tests
120. Build an abstraction on top of of an stateless wrapper Recap
121. Build an abstraction on top of of an stateless wrapper Take forward compatibility into account Recap
122. Build an abstraction on top of of an stateless wrapper Take forward compatibility into account Isolate test from undeterministic and slow dependencies. Recap
123. Build an abstraction on top of of an stateless wrapper Take forward compatibility into account Isolate test from undeterministic and slow dependencies. Don’t modify implementation and tests at the same time. Recap
124. Build an abstraction on top of of an stateless wrapper Take forward compatibility into account Isolate test from undeterministic and slow dependencies. Don’t modify implementation and tests at the same time. Don’t couple test with implementation details Recap
125. Build an abstraction on top of of an stateless wrapper Take forward compatibility into account Isolate test from undeterministic and slow dependencies. Don’t modify implementation and tests at the same time. Don’t couple test with implementation details Group errors by recover strategy Recap
126. Build an abstraction on top of of an stateless wrapper Take forward compatibility into account Isolate test from undeterministic and slow dependencies. Don’t modify implementation and tests at the same time. Don’t couple test with implementation details Group errors by recover strategy Recap
127. Thanks Say hi @luisobo