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с            1                      2
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ж            3                      4
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public int fn1(int a, int b) {
     return (a+(b-1))/b;
}

    public void Register(string name, string website, string comment)
    {
        var attendee = new Attendee(name, website, comment);
        _repository.SaveNewAttendee(attendee);
        RenderView("confirm", attendee);
    }

[Test]

public void ShouldSaveAttendee()
{
    var repository = new FakeRepository();

    var mockViewEngine = new MockViewEngine();
    var controller = new MainController(repository, mockViewEngine);
    controller.ControllerContext = new ControllerContext(new RequestContext(new HttpContextStub(), new RouteData()), controller);
    controller.Register("Jeffrey.',", "http://www.jeffreypalermo.com?=&@%20", "this comment!?,'.");

    Attendee attendee = repository.SavedAttendee;
    Assert.That(attendee.Name, Is.EqualTo("Jeffrey.',"));
    Assert.That(attendee.Website, Is.EqualTo("http://www.jeffreypalermo.com?=&@%20"));
    Assert.That(attendee.Comment, Is.EqualTo("this comment!?,'."));
 
    Assert.That(mockViewEngine.ActualViewContext.ViewName, Is.EqualTo("confirm"));
    Assert.That(mockViewEngine.ActualViewContext.ViewData, Is.EqualTo(attendee));
}

Michael Feathers' Working Effectively with Legacy Code (ISBN 0-13-117705-2) introduced a definition of legacy code as code without tests, which reflects the perspective of legacy code being difficult to work with in part due to a lack of automated regression tests. He also defined Characterization Tests to start putting legacy code under test.

There’s simply that much untested code. It’s better to write tests for the new code that you write and write tests for existing code you have to change, at the time you have to change it. Over time, you get more coverage, but your coverage percentage isn’t a goal. The goal is to make your changes safely.

...

The metric I’m thinking about is percentage of commits on files which are covered by tests relative to the number of commits on files without tests.

...

If you write tests for all of your changes, it will continue to rise. At a certain point, you may want to track only a window of commits, say, the commits which have happened only in the last year. When you do this, you can end up very close to 100%.

A>    public void Register(string name, string website, string comment)
A>    {
A>        var attendee = new Attendee(name, website, comment);
A>        _repository.SaveNewAttendee(attendee);
A>        RenderView("confirm", attendee);
A>    }
A>

A>[Test]

A>public void ShouldSaveAttendee()
A>{
A>    var repository = new FakeRepository();

A>    var mockViewEngine = new MockViewEngine();
A>    var controller = new MainController(repository, mockViewEngine);
A>    controller.ControllerContext = new ControllerContext(new RequestContext(new HttpContextStub(), new RouteData()), controller);
A>    controller.Register("Jeffrey.',", "http://www.jeffreypalermo.com?=&@%20", "this comment!?,'.");

A>    Attendee attendee = repository.SavedAttendee;
A>    Assert.That(attendee.Name, Is.EqualTo("Jeffrey.',"));
A>    Assert.That(attendee.Website, Is.EqualTo("http://www.jeffreypalermo.com?=&@%20"));
A>    Assert.That(attendee.Comment, Is.EqualTo("this comment!?,'."));
 
A>    Assert.That(mockViewEngine.ActualViewContext.ViewName, Is.EqualTo("confirm"));
A>    Assert.That(mockViewEngine.ActualViewContext.ViewData, Is.EqualTo(attendee));
A>}
A>

A>Так вот у МЕНЯ этого теста не будет. До тех пор, пока от тестируемого кода не будет зависить "чья нибудь жизнь".

SiteModel model;
public void SetUp() {
  model = ...; // Здесь вся лажа по созданию "лесов" для тестов.
}
[Test]
public void ShouldSaveAttendee()
{
    ViewContext resultView = model.controller.Register("Jeffrey.',", "http://www.jeffreypalermo.com?=&@%20", "this comment!?,'.");

    // Проверяем ожидаемое изменение состояния сайта
    Attendee attendee = model.repository.SavedAttendee; // TODO: скорее всего нужно model.repository.getLast() или что-то вроде того
    Assert.That(attendee.Name, Is.EqualTo("Jeffrey.',"));
    Assert.That(attendee.Website, Is.EqualTo("http://www.jeffreypalermo.com?=&@%20"));
    Assert.That(attendee.Comment, Is.EqualTo("this comment!?,'."));
 
    // Проверяем ответ веб сервера
    Assert.That(resultView.ViewName, Is.EqualTo("confirm"));
    Assert.That(resultView.ViewData, Is.EqualTo(attendee));
}

[Test]
public void TestRegisterAttendee()
{
    ViewContext resultView;

    // Normal case
    resultView = model.controller.Register("abc", "http://site.local?=&@%20", "comment");
    Assert.Equals("abc", model.model.repository.SavedAttendee.Name);
    Assert.Equals("confirm", resultView.ViewName);

    // Empty name
    resultView = model.controller.Register("", "http://site.local?=&@%20", "comment");
    Assert.IsNull(model.model.repository.SavedAttendee);
    Assert.Equals("ErrorView", resultView.ViewName);

    // и так далее на обработку всех ситуаций вызовов Register.
    // todo: Not Unique name
    // todo: Wrong URL
    // todo: Empty Comment
    // todo: Too long comment
    // todo: Not Unique URL

    // при этом вышеприведенный Ваш тест (ShouldSaveAttendee) нужно тоже оставить. Он 
    // полностью проверяет корректность рабоыт Register в нормальных условиях, а 
    // TestRegisterAttendee проверяет корректность работы в пограничных условиях.

}

Писать юнит тест для контроллера формы большого смыла не имеет. Тут больше подойдет тест конкретного сценария.

// ---------- application layer
package myapplayer;
class App1 {
  mybll.Bll1 bll;
  ...
  public Response registerAttendee(Attendee a) {
    try {
      bll.registerAttendee(a);
      return new AttendeeDisplayResponse(a);
    } catch (Exception e) {
      return new ErrorResponse(e);
    }
  }
}
// --------- UI layer ------
package myuilayer;
class PageRenderer { 
  // я в реальных проектах применяю XSLT для UI уровня, но тогда для 
  // новичков не наглядно (один из уровней приложения написан на функциональном языке - XSLT).
  public void render(HttpServletRequest req, HttpServletResponse res, Response r) {
    if(r instanceof AttendeeDisplayResponse) {
      AttendeeDisplayResponse ra = (AttendeeDisplayResponse)r;
      req.setAttribute("ATTENDEE", ra);
      transfer("Attendee.jsp");
    } else {
      throw new RuntimeException("Not implemented response");
    }
  }
}

   public Response registerAttendee(Attendee a) {
     try {
       bll.registerAttendee(a);
       return new AttendeeDisplayResponse(a);
       // Реакция на те же действия анонимного пользователя,
       // может быть определена в UI (а может и здесь)
       return (isAnonimous()
         ? RedirectResult.SignUp
         : new AttendeeDisplayResponse(a)
       );
     } catch (AccessViolationException e) {
       return new NoAccessResponse(e);
     } catch (DublicateAttendeeException e) {
       // этот catch можно было вообще не писать, уже все сделано!
       return new ErrorResponse(e);
     } catch (Exception e) {
       return new ErrorResponse(e);
     }
   }