2010 10 Behavior Driven Cocoa

7/27/2019 2010 10 Behavior Driven Cocoa

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Behavior Driven CocoaBDD with Cedar, OCHamcrest & OCMock

Friday, October 15, 2010


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Behavior Driven Development

Seeks a common language for Business andTechnology Getting the words right

Seeks identifiable, verifiable business value Is the feature worth the effort?

Seeks to reduce diminishing returns

resulting from large up-front design Enough is enough



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Its All Behavior

Behavior Driven Development (BDD) strives todescribe what a system should do, as

apposed to testing what the system does.

Its all about Getting the words right.



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Getting the Words Right

BDD strives to avoid the traditionaldisconnect between Business people and

Technology people through use of a common

vocabulary for describing the system.



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Programmers...

Why do I need to write tests? Thats what

testers do.

Writing all these tests slows me down! Its awaste of my time.

Im a good programmer! I dont need to writetests to prove my code works.



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Testers...

Why are programmers writing tests? We allknow they cant thats why you need testers!

Are you trying to take away our jobs?

You obviously dont understand testing or you

wouldnt be asking programmers write tests!



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Write Specs Not Tests

Simply eliminating the word testfrom the vocabulary can actually

relieve much of the tension between

Business, Development and Quality

Assurance teams.



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Specs! Not Functional

Specification Documents.

Theres nothing functional about afunctional specification!

Specs in this context are runnable,verifiable computer code that describes

how the application should behave.



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Wheres the Business Value?

Every feature of a system should be there

because it adds actual business value tothe product being built.

So define that value in each spec used to

describe the behavior of each feature?



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The User Story

Feature:Addition In orderto avoid silly mistakes

As amath idiot I wantto be told the sum of two numbers

Scenario:Add two numbers GivenI have entered 50 into the calculator

AndI have entered 70 into the calculator WhenI press add Thenthe result should be 120 on the screen



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Enough is Enough

Traditional large up-front design requires asking the

most important questions at a time when theteam has the least amount of knowledge.

This often requires making wild guesses about

the design, and scope, of a system before anyoneeven understands the product being built.



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Embrace Change

BDD/TDD strives to describe just enoughof the system to deliver something useful.

We call this the Red, Green, Refactor cycle.

Change is not only accepted, but is expected.

It is integrated directly into an agile planningand development process.



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CedarBDD Framework by Pivotal Labs

http://github.com/pivotal/cedar

http://github.com/pivotal/cedarhttp://github.com/pivotal/cedarhttp://github.com/pivotal/cedar


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Describe It!

SPEC_BEGIN(FooSpec)

describe(@"Foo", ^{ beforeEach(^{ ... });

it(@"should be awesome", ^{ ... });

});

SPEC_END



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It Should Behave Like

SPEC_BEGIN(FooSpec)

sharedExamplesFor(@"a similarly-behaving thing", ^(NSDictionary*context) { it(@"should do something common", ^{

... });});

describe(@"Something that shares behavior", ^{ itShouldBehaveLike(@"a similarly-behaving thing");});

describe(@"Something else that shares behavior", ^{ itShouldBehaveLike(@"a similarly-behaving thing");});

SPEC_END



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OCHamcrestMatcher Library for Objective-C

http://code.google.com/p/hamcrest/wiki/TutorialObjectiveC

http://code.google.com/p/hamcrest/wiki/TutorialObjectiveChttp://code.google.com/p/hamcrest/wiki/TutorialObjectiveChttp://code.google.com/p/hamcrest/wiki/TutorialObjectiveC


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Assert That!

NSString*myString = @"Foo";

assertThat(myString, equalTo(@"Foo"));

...or with a little syntactic sugar...

assertThat(myString, is(equalTo(@"Foo")));assertThat(myString, is(@"Foo"));



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Common Matchers

Core: anything, describedAs, is

Logical: allOf, anyOf, isNot

Object: equalTo, hasDescription, instanceOf,

isCompatableType, nilValue, notNilValue, sameInstance

Collections: hasEntry, hasKey, hasValue, hasItem, hasItems

Number: closeTo, greaterThan, greaterThanOrEqualTo, etc.

Text: equalToIgnoringCase, equalToIgnoringWhiteSpace,

containsString, startsWith, endsWith



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Use It with Anything

The OCHamcrest matchers can be

used with any test framework you

wish to use. It does not require Cedar.



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OCMockSometimes You Just Need to Fake It!

http://www.mulle-kybernetik.com/software/OCMock/

http://www.mulle-kybernetik.com/software/OCMock/http://www.mulle-kybernetik.com/software/OCMock/http://www.mulle-kybernetik.com/software/OCMock/


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Faking a Web Service Call

it(@"should authenticate", ^{ gr = [[GReaderalloc] init];

// Setup a mock to fake, and expect, the post message mock = [OCMockObjectpartialMockForObject:gr]; [[[mock expect] andReturn:@"I'm a fake response"] post:[OCMArgany]];

// Send a message to the real GRReader instance

[gr authenticateWithUsername:@"robert" password:@"password"];

[mock verify];});



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Use It with Anything

Like OCHamcrest, OCMock can be

used with any test framework you like.



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Demos...



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One more thing...



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BDD Your JavaScriptWith Jasmine (also from Pivotal Labs)

http://github.com/pivotal/jasmine

http://github.com/pivotal/jasminehttp://github.com/pivotal/jasminehttp://github.com/pivotal/jasmine


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A Jasmine Spec...

describe("Player", function() { varplayer; varsong; beforeEach(function() { player =newPlayer(); song =newSong(); }); it("should be able to play a Song", function() { player.play(song); expect(player.currentlyPlayingSong).toEqual(song); });});



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2010 10 Behavior Driven Cocoa

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