{"id":713,"date":"2009-02-23T18:07:08","date_gmt":"2009-02-23T17:07:08","guid":{"rendered":"http:\/\/www.navision-blog.de\/2009\/02\/23\/using-naturalspec-to-create-spec-for-c-projects\/"},"modified":"2009-11-08T11:16:57","modified_gmt":"2009-11-08T10:16:57","slug":"using-naturalspec-to-create-spec-for-c-projects","status":"publish","type":"post","link":"http:\/\/www.navision-blog.de\/blog\/2009\/02\/23\/using-naturalspec-to-create-spec-for-c-projects\/","title":{"rendered":"Using NaturalSpec to create a spec for C# projects (Updated 08.11.2009)"},"content":{"rendered":"

In my last two articles I gave an introduction<\/a> in NaturalSpec<\/a> and showed how to get started<\/a>. This time I will show how we can use NaturalSpec<\/a> to write automatically testable scenarios for C# projects.<\/p>\n

Like the TDD<\/a> principle \u201cWrite the tests first\u201d we should write our spec first and use the \u201cRed-Green-Refactor\u201d method.<\/p>\n

"Red" \u2013 Create a spec scenario that fails<\/h5>\n

At first I created a F# class library project called \u201cSpec.CarSelling\u201d and added project references to NaturalSpec.dll<\/em> and nunit.framework.dll<\/em> (see \u201cGetting started\u201d<\/a> for further explanations).<\/p>\n

Now I can write my first scenario:<\/p>\n

\/\/ 1. define the module\n<\/span>module <\/span>CarSpec<\/pre>\n
\/\/ 2. open the NaturalSpec namespace
<\/span>\nopen <\/span>NaturalSpec\n\n\/\/ 3. open project namespace\n<\/span>open <\/span>CarSellingLib\n\n\/\/ 4. define a test context\n<\/span>let <\/span>Bert = new <\/span>Dealer("Bert"<\/span>)\n\n\/\/ 5. create a method in BDD-style\n<\/span>let <\/span>selling_a_car_for amount (dealer:Dealer) =\n  printMethod amount\n  dealer.SellCar amount\n\n\/\/ 6. create a scenario\n<\/span>[<Scenario>]\nlet <\/span>When_selling_a_car_for_30000_it_should_equal_my_DreamCar() =\n  As Bert\n    |> When selling_a_car_for 30000\n    |> It should equal (new <\/span>Car(CarType.BMW, 200))\n    |> Verify<\/pre>\n
At this stage the scenario is ready but doesn\u2019t compile. This means we are ready with the "Red"-stage.<\/p>\n
"Green" \u2013 Make the test the pass<\/h5>\n
In order to get the test green we have to create a C# class library called CarSellingLib<\/strong> and define the enum CarType<\/strong> and the classes Dealer<\/strong> and Car<\/strong>. Sticking to the YAGNI-principle<\/a> we implement only the minimum to get the spec green (and ToString()-members for the output functionality).<\/p>\n
namespace <\/span>CarSellingLib\n{\n    public enum <\/span>CarType\n    <\/span>{\n        BMW\n    }\n}<\/pre>\n
\n  <\/p>\n
namespace <\/span>CarSellingLib\n{\n    public class <\/span>Car\n    <\/span>{\n        public <\/span>Car(CarType <\/span>type, int <\/span>horsePower)\n        {\n            Type = type;\n            HorsePower = horsePower;\n        }\n\n        public <\/span>CarType <\/span>Type { get<\/span>; set<\/span>; }\n        public int <\/span>HorsePower { get<\/span>; set<\/span>; }\n\n        public override string <\/span>ToString()\n        {\n            return string<\/span>.Format("{0} ({1} HP)"<\/span>, Type, HorsePower);\n        }\n\n        public override bool <\/span>Equals(object <\/span>obj)\n        {\n            var <\/span>y = obj as <\/span>Car<\/span>;\n            if<\/span>(y == null<\/span>) return false<\/span>;\n            return <\/span>Type == y.Type && HorsePower == y.HorsePower;\n        }\n    <\/span>}\n}
<\/pre>\n
using <\/span>System;\n\nnamespace <\/span>CarSellingLib\n{\n    public class <\/span>Dealer\n    <\/span>{\n        public <\/span>Dealer(string <\/span>name)\n        {\n            Name = name;\n        }\n\n        public string <\/span>Name { get<\/span>; set<\/span>; }\n\n        public <\/span>Car <\/span>SellCar(int <\/span>amount)\n        {\n            return new <\/span>Car<\/span>(CarType<\/span>.BMW, 200);\n        }\n\n        public override string <\/span>ToString()\n        {\n            return <\/span>Name;\n        }\n    }\n}<\/pre>\n
\n  
When we add a project reference to our spec-project the UnitTests should pass and we have completed the "Green" step. (See "Getting started<\/a>" if you don\u2019t know how to run the spec.) Now we can add some more scenarios to our spec: <\/p>\n
<\/p>\n
\/\/ 1. define the module 
<\/span>\nmodule <\/span>CarSpec<\/pre>\n
\/\/ 2. open NaturalSpec-Namespace\n<\/span>open <\/span>NaturalSpec\n\n\/\/ 3. open project namespace\n<\/span>open <\/span>CarSellingLib\n\n\/\/ 4. define a test context\n<\/span>let <\/span>Bert = new <\/span>Dealer("Bert"<\/span>)\n\n\/\/ define reusable values\n<\/span>let <\/span>DreamCar = new <\/span>Car(CarType.BMW, 200)\nlet <\/span>LameCar = new <\/span>Car(CarType.Fiat, 45)\n\n\/\/ 5. create a method in BDD-style\n<\/span>let <\/span>selling_a_car_for amount (dealer:Dealer) =\n  printMethod amount\n  dealer.SellCar amount\n\n\/\/ 6. create a scenario\n<\/span>[<Scenario>]\nlet <\/span>When_selling_a_car_for_30000_it_should_equal_the_DreamCar() =\n  As Bert\n    |> When selling_a_car_for 30000\n    |> It should equal DreamCar\n    |> It shouldn't equal LameCar\n    |> Verify      \n\n[<Scenario>]\nlet <\/span>When_selling_a_car_for_19000_it_should_equal_the_LameCar() =\n  As Bert\n    |> When selling_a_car_for 19000\n    |> It should equal LameCar\n    |> It shouldn't equal DreamCar\n    |> Verify<\/pre>\n
\n  <\/p>\n
\/\/ create a scenario that expects an error<\/span>\n[<Scenario>]\n[<Fails_with "Need more money"<\/span>>]\nlet <\/span>When_selling_a_car_for_1000_it_should_fail_with_Need_More_Money() =\n  As Bert\n    |> When selling_a_car_for 1000\n    |> Verify<\/pre>\n
Now we are in the \u201cRed\u201d-Phase again.<\/p>\n
"Refactor" – rearrange your code to eliminate duplication and follow patterns<\/h5>\n
After making the spec "Green" and doing some refactoring the project code could look like this:<\/p>\n
namespace <\/span>CarSellingLib\n{\n    public enum <\/span>CarType\n    <\/span>{\n        Fiat,\n        BMW\n    }\n}<\/pre>\n
\n  <\/p>\n
namespace <\/span>CarSellingLib\n{\n    public class <\/span>Car\n    <\/span>{\n        public <\/span>Car(CarType <\/span>type, int <\/span>horsePower)\n        {\n            Type = type;\n            HorsePower = horsePower;\n        }\n\n        public <\/span>CarType <\/span>Type { get<\/span>; set<\/span>; }\n        public int <\/span>HorsePower { get<\/span>; set<\/span>; }\n\n        # region <\/span>ToString, Equals \n\n        public override string <\/span>ToString()\n        {\n            return string<\/span>.Format("{0} ({1} HP)"<\/span>, Type, HorsePower);\n        }\n\n        public override bool <\/span>Equals(object <\/span>obj)\n        {\n            var <\/span>y = obj as <\/span>Car<\/span>;\n            if<\/span>(y == null<\/span>) return false<\/span>;\n            return <\/span>Type == y.Type && HorsePower == y.HorsePower;\n        }\n\n        #endregion\n    <\/span>}\n}<\/pre>\n
\n  <\/p>\n
using <\/span>System;\n\nnamespace <\/span>CarSellingLib\n{\n    public class <\/span>Dealer\n    <\/span>{\n        public <\/span>Dealer(string <\/span>name)\n        {\n            Name = name;\n        }\n\n        public string <\/span>Name { get<\/span>; set<\/span>; }\n\n        public <\/span>Car <\/span>SellCar(int <\/span>amount)\n        {\n            if <\/span>(amount > 20000)\n                return new <\/span>Car<\/span>(CarType<\/span>.BMW, 200);\n\n            if <\/span>(amount > 3000)\n                return new <\/span>Car<\/span>(CarType<\/span>.Fiat, 45);\n\n            throw new <\/span>Exception<\/span>("Need more money"<\/span>);\n        }\n\n        public override string <\/span>ToString()\n        {\n            return <\/span>Name;\n        }\n    }\n}<\/pre>\n
The spec output should look like the following:<\/p>\n
\n
Scenario: When selling a car for 1000 it should fail with Need More Money<\/p>\n
– Should fail…
\n    – As Bert
\n    – When selling a car for 1000<\/p>\n
Scenario: When selling a car for 19000 it should equal the LameCar<\/p>\n
– As Bert
\n    – When selling a car for 19000
\n    => It should equal Fiat (45 HP)
\n    => It should not equal BMW (200 HP)
\n    ==> OK<\/p>\n
Scenario: When selling a car for 30000 it should equal my DreamCar<\/p>\n
– As Bert
\n    – When selling a car for 30000
\n    => It should equal BMW (200 HP)
\n    ==> OK<\/p>\n
Scenario: When selling a car for 30000 it should equal the DreamCar<\/p>\n
– As Bert
\n    – When selling a car for 30000
\n    => It should equal BMW (200 HP)
\n    => It should not equal Fiat (45 HP)
\n    >==> OK<\/p>\n
4 passed, 0 failed, 0 skipped, took 1,81 seconds (NUnit 2.5).<\/p>\n<\/blockquote>\n
Summary<\/h5>\n
I showed how we can use NaturalSpec for the Red-Green-Refactor process of C# projects and how easy it is to get a spec in natural language.<\/p>\n","protected":false},"excerpt":{"rendered":"
In my last two articles I gave an introduction in NaturalSpec and showed how to get started. This time I will show how we can use NaturalSpec to write automatically testable scenarios for C# projects. Like the TDD principle \u201cWrite the tests first\u201d we should write our spec first and use the \u201cRed-Green-Refactor\u201d method. "Red" […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[448,524],"tags":[634,533,664,666,526,531],"_links":{"self":[{"href":"http:\/\/www.navision-blog.de\/blog\/wp-json\/wp\/v2\/posts\/713"}],"collection":[{"href":"http:\/\/www.navision-blog.de\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.navision-blog.de\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.navision-blog.de\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.navision-blog.de\/blog\/wp-json\/wp\/v2\/comments?post=713"}],"version-history":[{"count":19,"href":"http:\/\/www.navision-blog.de\/blog\/wp-json\/wp\/v2\/posts\/713\/revisions"}],"predecessor-version":[{"id":917,"href":"http:\/\/www.navision-blog.de\/blog\/wp-json\/wp\/v2\/posts\/713\/revisions\/917"}],"wp:attachment":[{"href":"http:\/\/www.navision-blog.de\/blog\/wp-json\/wp\/v2\/media?parent=713"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.navision-blog.de\/blog\/wp-json\/wp\/v2\/categories?post=713"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.navision-blog.de\/blog\/wp-json\/wp\/v2\/tags?post=713"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}