Autofixture - 創建一個float，double或decimal，餘數爲

Question

如何修改Float，Double和decimal的AutoFixture創建方法，以便在創建這些類型時還會有餘數？

目前我這樣做，但這會拋出異常。

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

試圖通過使用的值，以重新定義類型（double）相同類型（double）確實會產生無限遞歸。但是，通過將種子輸入更改爲另一種類型即可輕鬆完成此工作 - 例如，一個int：

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

雙打現在往往也有分數值。

Answer 2

一種選擇是使用自定義ISpecimenBuilder：

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

的RandomDoublePrecisionFloatingPointSequenceGenerator可能看起來像下面：

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); 
     } 
    } 
}