我正在尝试克服一个类具有字符串构造函数参数的情况，该参数不能被Autofixture生成的任何旧字符串（Guid-y外观值）所满足。
在您想要简单地回答链接之前 Mark Seemann的关于基于会议的定制的Ploeh博客文章，让我说，我一直在引用它和他的其他博客条目进行此测试，我无法通过。
当我在调试中单步执行时，我可以看到构造函数参数在某些时候传入了有效值，但测试仍然失败并带有Guid-y Color值。我认为这与存在“颜色”参数值这一事实有关， 和 由Autofixture填充的“颜色”属性。是不是我编写了一个解决构造函数参数的ISpecimenBuilder，但我正在测试公共属性值（两个不同的东西）？
我知道所有这些对于这个例子来说都是过度的，但我想到了一个更复杂的场景，其中使用了 Build<T>().With() 方法不会是DRY。
失败测试
[Fact]
public void Leaf_Color_Is_Brown()
{
// arrange
var fixture = new Fixture().Customize(new LeafColorCustomization());
// act
var leaf = fixture.Create<Leaf>();
// using .Build<>.With(), test passes
//var leaf = fixture.Build<Leaf>().With(l => l.Color, "brown").CreateAnonymous();
// assert
Assert.True(leaf.Color == "brown");
}
SUT
public class Leaf
{
public Leaf(string color)
{
if (color != "brown")
throw new ArgumentException(@"NO LEAF FOR YOU!");
this.Color = color;
}
public string Color { get; set; }
}
CompositeCustomization实现 （我知道在这个例子中不需要AutoMoqCustomization（））
public class LeafCustomization : CompositeCustomization
{
public LeafCustomization()
: base(
new LeafColorCustomization(),
new AutoMoqCustomization()) { }
}
叶特定的ICustomization
public class LeafColorCustomization : ICustomization
{
public void Customize(IFixture fixture)
{
if (fixture == null)
throw new ArgumentNullException("fixture");
fixture.Customizations.Add(new LeafBuilder());
}
}
String-constructor-with-name-of-Color特定的ISpecimenBuilder
public class LeafBuilder : ISpecimenBuilder
{
public object Create(object request, ISpecimenContext context)
{
var pi = request as ParameterInfo;
if (pi == null)
return new NoSpecimen(request);
if (pi.ParameterType != typeof(string) || pi.Name != "color")
return new NoSpecimen(request);
return "brown";
}
}
解决方案1：
注册那个 Color 作为后处理的一部分，不应为可写属性分配任何自动值：
internal class LeafColorCustomization : ICustomization
{
public void Customize(IFixture fixture)
{
fixture.Customize<Leaf>(c => c
.Without(x => x.Color));
fixture.Customizations.Add(new LeafBuilder());
}
}
解决方案2：
制作 Color 财产只读：
public class Leaf
{
private readonly string color;
public Leaf(string color)
{
if (color != "brown")
throw new ArgumentException(@"NO LEAF FOR YOU!");
this.color = color;
}
public string Color
{
get { return this.color; }
}
}
自从 Color 属性是只读的AutoFixture不会为它分配值。
以上解决方案也适用于AutoFixture 2。
解决方案1：
注册那个 Color 作为后处理的一部分，不应为可写属性分配任何自动值：
internal class LeafColorCustomization : ICustomization
{
public void Customize(IFixture fixture)
{
fixture.Customize<Leaf>(c => c
.Without(x => x.Color));
fixture.Customizations.Add(new LeafBuilder());
}
}
解决方案2：
制作 Color 财产只读：
public class Leaf
{
private readonly string color;
public Leaf(string color)
{
if (color != "brown")
throw new ArgumentException(@"NO LEAF FOR YOU!");
this.color = color;
}
public string Color
{
get { return this.color; }
}
}
自从 Color 属性是只读的AutoFixture不会为它分配值。
以上解决方案也适用于AutoFixture 2。
假设你单独处理属性设置的东西，这里是一个构造函数参数限制 Customization 这样做的诀窍：
class BrownLeavesCustomization : ICustomization
{
void ICustomization.Customize( IFixture fixture )
{
Func<string> notBrownGenerator = fixture.Create<Generator<string>>()
.SkipWhile( x => x == "Brown" )
.First;
fixture.Customizations.Add(
ArgumentGeneratorCustomization<Leaf>.ForConstructorArgument(
"color",
notBrownGenerator ) );
}
static class ArgumentGeneratorCustomization<T>
{
public static ISpecimenBuilder ForConstructorArgument<TArg>( string argumentName, Func<TArg> generator )
{
return new ConstructorArgumentGenerator<TArg>( argumentName, generator );
}
class ConstructorArgumentGenerator<TArg> : ISpecimenBuilder
{
readonly string _argumentName;
readonly Func<TArg> _generator;
public ConstructorArgumentGenerator( string argumentName, Func<TArg> generator )
{
Assert.Contains( argumentName, from ctor in typeof( T ).GetConstructors() from param in ctor.GetParameters() select param.Name );
_argumentName = argumentName;
_generator = generator;
}
object ISpecimenBuilder.Create( object request, ISpecimenContext context )
{
var pi = request as ParameterInfo;
if ( pi == null )
return new NoSpecimen( request );
if ( pi.Member.DeclaringType != typeof( T ) )
return new NoSpecimen( request );
if ( pi.Member.MemberType != MemberTypes.Constructor )
return new NoSpecimen( request );
if ( pi.ParameterType != typeof( TArg ) )
return new NoSpecimen( request );
if ( pi.Name != _argumentName )
return new NoSpecimen( request );
return _generator();
}
}
}
}
解决方案:(基于Mark Seemann的 评论这个答案）
在ISpecimenBuilder实现中容纳构造函数参数和可写属性，除了在LeafColorCustomization中添加LeafBuilder实例之外什么都不做：
public class LeafBuilder : ISpecimenBuilder
{
public object Create(object request, ISpecimenContext context)
{
var paramInfo = request as ParameterInfo;
if (paramInfo != null
&& paramInfo.ParameterType == typeof(string)
&& paramInfo.Name == "color")
{ return "brown"; }
var propInfo = request as PropertyInfo;
if (propInfo != null
&& propInfo.PropertyType == typeof(string)
&& propInfo.Name == "Color")
{ return "brown"; }
return new NoSpecimen(request);
}
}
internal class LeafColorCustomization : ICustomization
{
public void Customize(IFixture fixture)
{
fixture.Customizations.Add(new LeafBuilder());
}
}