Autofixture - 创建一个float，double或decimal，余数为

Question

如何修改Float，Double和decimal的AutoFixture创建方法，以便在创建这些类型时还会有余数？

目前我这样做，但这会抛出异常。

var fixture = new Fixture(); 
fixture.Customize<double>(sb => sb.FromFactory<double>(d => d * 1.33)); //This should add remainder 
var value = fixture.Create<double>(); 

Answer 1

试图通过使用的值，以重新定义类型（double）相同类型（double）确实会产生无限递归。但是，通过将种子输入更改为另一种类型即可轻松完成此工作 - 例如，一个int：

var fixture = new Fixture(); 
fixture.Customize<double>(c => c.FromFactory<int>(i => i * 1.33)); 
var value = fixture.Create<double>(); 

双打现在往往也有分数值。

Answer 2

一种选择是使用自定义ISpecimenBuilder：

var fixture = new Fixture(); 
fixture.Customizations.Add(
    new RandomDoublePrecisionFloatingPointSequenceGenerator()); 

的RandomDoublePrecisionFloatingPointSequenceGenerator可能看起来像下面：

internal class RandomDoublePrecisionFloatingPointSequenceGenerator 
    : ISpecimenBuilder 
{ 
    private readonly object syncRoot; 
    private readonly Random random; 

    internal RandomDoublePrecisionFloatingPointSequenceGenerator() 
    { 
     this.syncRoot = new object(); 
     this.random = new Random(); 
    } 

    public object Create(object request, ISpecimenContext context) 
    { 
     var type = request as Type; 
     if (type == null) 
      return new NoSpecimen(request); 

     return this.CreateRandom(type); 
    } 

    private double GetNextRandom() 
    { 
     lock (this.syncRoot) 
     { 
      return this.random.NextDouble(); 
     } 
    } 

    private object CreateRandom(Type request) 
    { 
     switch (Type.GetTypeCode(request)) 
     { 
      case TypeCode.Decimal: 
       return (decimal) 
        this.GetNextRandom(); 

      case TypeCode.Double: 
       return (double) 
        this.GetNextRandom(); 

      case TypeCode.Single: 
       return (float) 
        this.GetNextRandom(); 

      default: 
       return new NoSpecimen(request); 
     } 
    } 
}