BDD とは？ 振る舞いを決めた上で開発を進める手法（スペックファースト）

title: BDD とは？ 振る舞いを決めた上で開発を進める手法（スペックファースト）
url: http://cs.gogo-asp.net/blogs/naoki/archive/2012/04/17/SpecFlow-_6830_-WatiN-_92302952287557305F30_-BDD-_6E30966E9950_.aspx

snippet:
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BDD は Behavior Driven Development の略で、振る舞いを決めた上で開発を進める手法（スペックファースト）の事です。

SpecFlow や WatiN などがこの代表的なツールです。SpecFlow は Visual Studio 内での仕様の作成と実施をサポートし、WatiN はブラウザーを使用して、エンド ツー エンドの自動システム テストを実行できるようにします。

サンプルコード
using NSpec;

class describe_specifications : nspec
{
    void when_creating_specifications()
    {
        //some of these specifications are meant to fail so you can see what the output looks like
        it["true should be false"] = () => true.should_be_false();
        it["enumerable should be empty"] = () => new int[] { }.should_be_empty();
        it["enumerable should contain 1"] = () => new[] { 1 }.should_contain(1);
        it["enumerable should not contain 1"] = () => new[] { 1 }.should_not_contain(1);
        it["1 should be 2"] = () => 1.should_be(2);
        it["1 should be 1"] = () => 1.should_be(1);
        it["1 should not be 1"] = () => 1.should_not_be(1);
        it["1 should not be 2"] = () => 1.should_not_be(2);
        it["\"\" should not be null"] = () => "".should_not_be_null();
        it["some object should not be null"] = () => someObject.should_not_be_null();
        //EXPERIMENTAL - specify only takes a lambda and does
        //its best to make a sentence out of the code. YMMV.
        specify = ()=> "ninja".should_not_be("pirate");
    }
    object someObject = null;
}

サンプルスペック出力
describe specifications
  when creating specifications
    true should be false - FAILED - Expected: False, But was: True
    enumerable should be empty
    enumerable should contain 1
    enumerable should not contain 1 - FAILED - Expected: not collection containing 1, But was:...
    1 should be 2 - FAILED - Expected: 2, But was: 1
    1 should be 1
    1 should not be 1 - FAILED - Expected: not 1, But was: 1
    1 should not be 2
    "" should not be null
    some object should not be null - FAILED - Expected: not null, But was: null
    ninja should not be pirate

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