13

我正在尝试克服一个场景，其中一个类具有一个字符串构造函数参数，该参数不能被 Autofixture 生成的任何旧字符串（Guid-y 外观值）所满足。

在您想简单地通过Mark Seemann 的 Ploeh 博客文章的基于约定的定制的链接来回答之前，让我说我一直在参考它和他的其他博客文章来进行这个测试，我无法访问经过。

当我单步调试时，我可以看到在某些时候构造函数参数传入了有效值，但测试仍然失败，并显示 Guid-y 颜色值。我认为这与Autofixture 填充“颜色”参数值和“颜色”属性有关。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示例来说都是多余的，但我设想了一个更复杂的场景，使用该Build<T>().With()方法不会是 DRY。

失败的测试

    [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（我知道此示例中不需要 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());
        }
    }

带有颜色名称的字符串构造函数 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";
        }
    }
4

3 回答 3

9

解决方案 1：

注册Color可写属性不应被分配任何自动值作为后处理的一部分：

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：

将Color属性设为只读：

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; }
    }
}

由于该Color属性是只读的，AutoFixture 不会为其分配值。

上述解决方案也适用于 AutoFixture 2。

于 2013-03-20T21:06:54.170 回答
5

假设您分别处理属性设置的东西，这里有一个构造函数参数限制Customization可以解决问题：

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();
            }
        }
    }
}
于 2013-03-21T14:37:44.240 回答
3

解决方案：（基于 Mark Seemann对此答案的评论）

在 ISpecimenBuilder 实现中同时容纳构造函数参数和 writeable 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());
    }
}
于 2013-03-22T02:32:13.210 回答