AutoFixture：配置开放式仿制标本生成器 [英] AutoFixture: Configuring an Open Generics Specimen Builder
问题描述
我有一个使用Open Generics的对象模型（是的，是的，现在我有两个问题;这就是为什么我在这里:)： - $ / b>
public interface IOGF< T>
{
}
class C
{
}
class D
{
只读IOGF< c取代; _ogf;
public D（IOGF< C> ogf）
{
_ogf = ogf;
$ b我试图让AutoFixture生成匿名实例上面的 D 。但是，AutoFixture本身没有构建 IOGF<> 的内置策略，因此我们观察到： public class OpenGenericsBinderDemo
{
[Fact]
public void X（）
{
var fixture =新的Fixture（）; $（b）b
$ b Assert.Throws< Ploeh.AutoFixture.ObjectCreationException>（（）=>
fixture.CreateAnonymous< D>）;
$ / code>
基本信息是：
Ploeh.AutoFixture.ObjectCreationException：AutoFixture无法从IOGF`1 [C]创建实例，很可能是因为它没有公共构造函数，是抽象类型或非公共类型。
我很高兴为它提供一个具体的实现：
public class OGF< T> ：IOGF< T>
{
public OGF（IX x）
{
}
}
公共接口IX
{
}
public class X：IX
{
}
和一个关联的绑定：
fixture.Register< IX，X>（）;
我如何（或者我应该怎么看待这个问题？）做下面的测试（）
public class OpenGenericsLearning
{
[Fact]
public void OpenGenericsDontGetResolved（）
{
var fixture = new Fixture（）; （b）。fixture.ject< IX>（fixture.Freeze< X>（））;
// TODO注册或做一些提供
// OGF< C>以满足D的IOGF C< C>要求
Assert.NotNull（fixture.CreateAnonymous< D>）;;
$ / code $ / pre
$ b $（有关于codeplex的讨论和问题网站 - 我只是需要一个快速实现这一点，并打算删除这个，如果这只是一个坏主意和/或我错过了什么）
编辑2 ：（参见马克答案的评论）这里的（被承认设计的）上下文是对一个大的几乎完整的系统System Under Test对象图的验收测试，而不是一个小的（受控/易于理解:)对或三重类在单元或集成测试场景中。正如在自问题括号声明中所暗示的那样，我并不完全相信这种类型的测试甚至是合理的。
解决方案您可以创建一个自定义，其工作原理如下：
public class AnOpenGenericsBinderDemo
{
[Fact]
public void RegisteringGenericBinderShouldEnableResolution（）
{
var fixture = new Fixture（）; （b）。fixture.ject< IX>（fixture.Freeze< X>（））; $ type（OGF<>））;
Assert.IsType< OGF< C>>（fixture.CreateAnonymous< D>）.Ogf;
$ b 并且这样执行：
public static class AutoFixtureOpenGenericsExtensions
{
public static void RegisterOpenGenericImplementation（this IFixture that，Type serviceType，Type componentType）
{
if（！serviceType.ContainsGenericParameters）
throw new ArgumentException（must open generic，serviceType）;
if（！componentType.ContainsGenericParameters）
throw new ArgumentException（must open generic，componentType）;
// TODO验证每种情况下类型参数的数量为1
that.Customize（new OpenGenericsBinderCustomization（serviceType，componentType））;
}
公共类OpenGenericsBinderCustomization：ICustomization
{
只读类型_serviceType;
只读类型_componentType;
public OpenGenericsBinderCustomization（类型serviceType，类型componentType）
{
_serviceType = serviceType;
_componentType = componentType;
}
void ICustomization.Customize（IFixture fixture）
{
fixture.Customizations.Add（new OpenGenericsSpecimenBuilder（_serviceType，_componentType））;
}
类OpenGenericsSpecimenBuilder：ISpecimenBuilder
{
只读类型_serviceType;
只读类型_componentType;
public OpenGenericsSpecimenBuilder（类型serviceType，类型componentType）
{
_serviceType = serviceType;
_componentType = componentType;
}
object ISpecimenBuilder.Create（object request，ISpecimenContext context）
{
var typedRequest = request as Type;
if（typedRequest！= null&& typedRequest.IsGenericType&&& typedRequest.GetGenericTypeDefinition（）== _serviceType）
return context.Resolve（_componentType.MakeGenericType（typedRequest.GetGenericArguments（）。Single （）））;
返回新的NoSpecimen（请求）;
}
}
}
}
I编辑：下面是带感应属性的更新D：
编辑： p>
class D
{
只读IOGF< C> _ogf;
public D（IOGF< C> ogf）
{
_ogf = ogf;
}
public IOGF< C> Ogf
{
get {return _ogf; }
}
}
I have an object model that uses Open Generics (Yes, yes, now I have two problems; that's why I'm here :) :-
public interface IOGF<T>
{
}
class C
{
}
class D
{
readonly IOGF<C> _ogf;
public D( IOGF<C> ogf )
{
_ogf = ogf;
}
}
I'm trying to get AutoFixture to generate Anonymous instances of D above. However, on its own, AutoFixture doesn't have a built in strategy for building an IOGF<> and hence we observe:
public class OpenGenericsBinderDemo
{
[Fact]
public void X()
{
var fixture = new Fixture();
Assert.Throws<Ploeh.AutoFixture.ObjectCreationException>( () =>
fixture.CreateAnonymous<D>() );
}
The underlying message is:
Ploeh.AutoFixture.ObjectCreationException : AutoFixture was unable to create an instance from IOGF`1[C], most likely because it has no public constructor, is an abstract or non-public type.
I'm happy to provide it a concrete implementation:
public class OGF<T> : IOGF<T>
{
public OGF( IX x )
{
}
}
public interface IX
{
}
public class X : IX
{
}
And an associated binding:
fixture.Register<IX,X>();
How do I (or should I even look at the problem that way??) make the following test pass?
public class OpenGenericsLearning
{
[Fact]
public void OpenGenericsDontGetResolved()
{
var fixture = new Fixture();
fixture.Inject<IX>( fixture.Freeze<X>() );
// TODO register or do something that will provide
// OGF<C> to fulfill D's IOGF<C> requirement
Assert.NotNull( fixture.CreateAnonymous<D>());
}
}
(There are discussions and issues around this on the codeplex site - I just needed to a quick impl of this and am open to deleting this if this is just a bad idea and/or I've missed something)
EDIT 2: (See also comment on Mark's answer) The (admittedly contrived) context here is an acceptance test on a large 'almost full system' System Under Test object graph rather than a small (controlled/easy to grok :) pair or triplet of classes in a unit or integration test scenario. As alluded to in the self-question parenthetical statement, I'm not fully confident this type of test even makes sense though.
解决方案 You could create a customization which works as follows:
public class AnOpenGenericsBinderDemo
{
[Fact]
public void RegisteringAGenericBinderShouldEnableResolution()
{
var fixture = new Fixture();
fixture.Inject<IX>( fixture.Freeze<X>() );
fixture.RegisterOpenGenericImplementation( typeof( IOGF<> ), typeof( OGF<> ) );
Assert.IsType<OGF<C>>( fixture.CreateAnonymous<D>().Ogf );
}
}
And is implemented like so:
public static class AutoFixtureOpenGenericsExtensions
{
public static void RegisterOpenGenericImplementation( this IFixture that, Type serviceType, Type componentType )
{
if ( !serviceType.ContainsGenericParameters )
throw new ArgumentException( "must be open generic", "serviceType" );
if ( !componentType.ContainsGenericParameters )
throw new ArgumentException( "must be open generic", "componentType" );
// TODO verify number of type parameters is 1 in each case
that.Customize( new OpenGenericsBinderCustomization( serviceType, componentType ) );
}
public class OpenGenericsBinderCustomization : ICustomization
{
readonly Type _serviceType;
readonly Type _componentType;
public OpenGenericsBinderCustomization( Type serviceType, Type componentType )
{
_serviceType = serviceType;
_componentType = componentType;
}
void ICustomization.Customize( IFixture fixture )
{
fixture.Customizations.Add( new OpenGenericsSpecimenBuilder( _serviceType, _componentType ) );
}
class OpenGenericsSpecimenBuilder : ISpecimenBuilder
{
readonly Type _serviceType;
readonly Type _componentType;
public OpenGenericsSpecimenBuilder( Type serviceType, Type componentType )
{
_serviceType = serviceType;
_componentType = componentType;
}
object ISpecimenBuilder.Create( object request, ISpecimenContext context )
{
var typedRequest = request as Type;
if ( typedRequest != null && typedRequest.IsGenericType && typedRequest.GetGenericTypeDefinition() == _serviceType )
return context.Resolve( _componentType.MakeGenericType( typedRequest.GetGenericArguments().Single() ) );
return new NoSpecimen( request );
}
}
}
}
I assume someone has a better implementation than that though and/or there is a built-in implementation.
EDIT: The following is the updated D with the sensing property:
class D
{
readonly IOGF<C> _ogf;
public D( IOGF<C> ogf )
{
_ogf = ogf;
}
public IOGF<C> Ogf
{
get { return _ogf; }
}
}
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