我正在尝试使用Pex来测试一些代码。我有一个抽象类，有四个具体的实现。我为四种具体类型中的每一种创建了工厂方法。我还为抽象类型创建了一个，除了this nice thread解释，Pex不会使用抽象工厂方法，也不应该。
问题是我的一些代码依赖于四种具体类型（因为创建更多的子类非常非常不可能），但是Pex通过使用Moles来创建一个代码来破坏代码残余部分。
如何强制Pex使用其中一个工厂方法（任何一个，我不关心）来创建抽象类的实例而不为该抽象类创建Moles存根？是否有PexAssume指令可以完成此任务？请注意，某些具体类型构成了一种树结构，因此说ConcreteImplementation来自AbstractClass，而ConcreteImplementation有两种属性AbstractClass。我需要确保树中的任何地方都没有使用存根。 （并非所有具体实现都具有AbstractClass属性。）
修改
似乎我需要添加一些关于类结构本身如何工作的更多信息，但要记住，目标仍然是如何让Pex不要使用存根类。
以下是抽象基类的简化版本及其四个具体实现。
public abstract class AbstractClass
{
public abstract AbstractClass Distill();
public static bool operator ==(AbstractClass left, AbstractClass right)
{
// some logic that returns a bool
}
public static bool operator !=(AbstractClass left, AbstractClass right)
{
// some logic that basically returns !(operator ==)
}
public static Implementation1 Implementation1
{
get
{
return Implementation1.GetInstance;
}
}
}
public class Implementation1 : AbstractClass, IEquatable<Implementation1>
{
private static Implementation1 _implementation1 = new Implementation1();
private Implementation1()
{
}
public override AbstractClass Distill()
{
return this;
}
internal static Implementation1 GetInstance
{
get
{
return _implementation1;
}
}
public bool Equals(Implementation1 other)
{
return true;
}
}
public class Implementation2 : AbstractClass, IEquatable<Implementation2>
{
public string Name { get; private set; }
public string NamePlural { get; private set; }
public Implementation2(string name)
{
// initializes, including
Name = name;
// and sets NamePlural to a default
}
public Implementation2(string name, string plural)
{
// initializes, including
Name = name;
NamePlural = plural;
}
public override AbstractClass Distill()
{
if (String.IsNullOrEmpty(Name))
{
return AbstractClass.Implementation1;
}
return this;
}
public bool Equals(Implementation2 other)
{
if (other == null)
{
return false;
}
return other.Name == this.Name;
}
}
public class Implementation3 : AbstractClass, IEquatable<Implementation3>
{
public IEnumerable<AbstractClass> Instances { get; private set; }
public Implementation3()
: base()
{
Instances = new List<AbstractClass>();
}
public Implementation3(IEnumerable<AbstractClass> instances)
: base()
{
if (instances == null)
{
throw new ArgumentNullException("instances", "error msg");
}
if (instances.Any<AbstractClass>(c => c == null))
{
thrown new ArgumentNullException("instances", "some other error msg");
}
Instances = instances;
}
public override AbstractClass Distill()
{
IEnumerable<AbstractClass> newInstances = new List<AbstractClass>(Instances);
// "Flatten" the collection by removing nested Implementation3 instances
while (newInstances.OfType<Implementation3>().Any<Implementation3>())
{
newInstances = newInstances.Where<AbstractClass>(c => c.GetType() != typeof(Implementation3))
.Concat<AbstractClass>(newInstances.OfType<Implementation3>().SelectMany<Implementation3, AbstractUnit>(i => i.Instances));
}
if (newInstances.OfType<Implementation4>().Any<Implementation4>())
{
List<AbstractClass> denominator = new List<AbstractClass>();
while (newInstances.OfType<Implementation4>().Any<Implementation4>())
{
denominator.AddRange(newInstances.OfType<Implementation4>().Select<Implementation4, AbstractClass>(c => c.Denominator));
newInstances = newInstances.Where<AbstractClass>(c => c.GetType() != typeof(Implementation4))
.Concat<AbstractClass>(newInstances.OfType<Implementation4>().Select<Implementation4, AbstractClass>(c => c.Numerator));
}
return (new Implementation4(new Implementation3(newInstances), new Implementation3(denominator))).Distill();
}
// There should only be Implementation1 and/or Implementation2 instances
// left. Return only the Implementation2 instances, if there are any.
IEnumerable<Implementation2> i2s = newInstances.Select<AbstractClass, AbstractClass>(c => c.Distill()).OfType<Implementation2>();
switch (i2s.Count<Implementation2>())
{
case 0:
return AbstractClass.Implementation1;
case 1:
return i2s.First<Implementation2>();
default:
return new Implementation3(i2s.OrderBy<Implementation2, string>(c => c.Name).Select<Implementation2, AbstractClass>(c => c));
}
}
public bool Equals(Implementation3 other)
{
// omitted for brevity
return false;
}
}
public class Implementation4 : AbstractClass, IEquatable<Implementation4>
{
private AbstractClass _numerator;
private AbstractClass _denominator;
public AbstractClass Numerator
{
get
{
return _numerator;
}
set
{
if (value == null)
{
throw new ArgumentNullException("value", "error msg");
}
_numerator = value;
}
}
public AbstractClass Denominator
{
get
{
return _denominator;
}
set
{
if (value == null)
{
throw new ArgumentNullException("value", "error msg");
}
_denominator = value;
}
}
public Implementation4(AbstractClass numerator, AbstractClass denominator)
: base()
{
if (numerator == null || denominator == null)
{
throw new ArgumentNullException("whichever", "error msg");
}
Numerator = numerator;
Denominator = denominator;
}
public override AbstractClass Distill()
{
AbstractClass numDistilled = Numerator.Distill();
AbstractClass denDistilled = Denominator.Distill();
if (denDistilled.GetType() == typeof(Implementation1))
{
return numDistilled;
}
if (denDistilled.GetType() == typeof(Implementation4))
{
Implementation3 newInstance = new Implementation3(new List<AbstractClass>(2) { numDistilled, new Implementation4(((Implementation4)denDistilled).Denominator, ((Implementation4)denDistilled).Numerator) });
return newInstance.Distill();
}
if (numDistilled.GetType() == typeof(Implementation4))
{
Implementation4 newImp4 = new Implementation4(((Implementation4)numReduced).Numerator, new Implementation3(new List<AbstractClass>(2) { ((Implementation4)numDistilled).Denominator, denDistilled }));
return newImp4.Distill();
}
if (numDistilled.GetType() == typeof(Implementation1))
{
return new Implementation4(numDistilled, denDistilled);
}
if (numDistilled.GetType() == typeof(Implementation2) && denDistilled.GetType() == typeof(Implementation2))
{
if (((Implementation2)numDistilled).Name == (((Implementation2)denDistilled).Name)
{
return AbstractClass.Implementation1;
}
return new Implementation4(numDistilled, denDistilled);
}
// At this point, one or both of numerator and denominator are Implementation3
// instances, and the other (if any) is Implementation2. Because both
// numerator and denominator are distilled, all the instances within either
// Implementation3 are going to be Implementation2. So, the following should
// work.
List<Implementation2> numList =
numDistilled.GetType() == typeof(Implementation2) ? new List<Implementation2>(1) { ((Implementation2)numDistilled) } : new List<Implementation2>(((Implementation3)numDistilled).Instances.OfType<Implementation2>());
List<Implementation2> denList =
denDistilled.GetType() == typeof(Implementation2) ? new List<Implementation2>(1) { ((Implementation2)denDistilled) } : new List<Implementation2>(((Implementation3)denDistilled).Instances.OfType<Implementation2>());
Stack<int> numIndexesToRemove = new Stack<int>();
for (int i = 0; i < numList.Count; i++)
{
if (denList.Remove(numList[i]))
{
numIndexesToRemove.Push(i);
}
}
while (numIndexesToRemove.Count > 0)
{
numList.RemoveAt(numIndexesToRemove.Pop());
}
switch (denList.Count)
{
case 0:
switch (numList.Count)
{
case 0:
return AbstractClass.Implementation1;
case 1:
return numList.First<Implementation2>();
default:
return new Implementation3(numList.OfType<AbstractClass>());
}
case 1:
switch (numList.Count)
{
case 0:
return new Implementation4(AbstractClass.Implementation1, denList.First<Implementation2>());
case 1:
return new Implementation4(numList.First<Implementation2>(), denList.First<Implementation2>());
default:
return new Implementation4(new Implementation3(numList.OfType<AbstractClass>()), denList.First<Implementation2>());
}
default:
switch (numList.Count)
{
case 0:
return new Implementation4(AbstractClass.Implementation1, new Implementation3(denList.OfType<AbstractClass>()));
case 1:
return new Implementation4(numList.First<Implementation2>(), new Implementation3(denList.OfType<AbstractClass>()));
default:
return new Implementation4(new Implementation3(numList.OfType<AbstractClass>()), new Implementation3(denList.OfType<AbstractClass>()));
}
}
}
public bool Equals(Implementation4 other)
{
return Numerator.Equals(other.Numerator) && Denominator.Equals(other.Denominator);
}
}
我想要测试的核心是Distill方法，正如您所看到的那样，它有可能以递归方式运行。因为存在的AbstractClass在这个范例中没有意义，所以它打破了算法逻辑。即使尝试测试存根类也有些无用，因为除了抛出异常或假装它是Implementation1的实例之外，我几乎无能为力。我宁愿不必重写被测试的代码以适应这种方式的特定测试框架，但是以永远不会存根AbstractClass的方式编写测试本身就是我想要做的。< / p>
我希望很明显我正在做的事情与类型安全的枚举构造有什么不同。此外，我匿名化了在这里发布的对象（你可以告诉），我没有包括所有方法，所以如果你要评论告诉我Implementation4.Equals(Implementation4)已经坏了，不要担心，我我知道它在这里被打破了，但我的实际代码处理了这个问题。
另一个编辑：
以下是其中一个工厂类的示例。它位于Pex生成的测试项目的Factories目录中。
public static partial class Implementation3Factory
{
[PexFactoryMethod(typeof(Implementation3))]
public static Implementation3 Create(IEnumerable<AbstractClass> instances, bool useEmptyConstructor)
{
Implementation3 i3 = null;
if (useEmptyConstructor)
{
i3 = new Implementation3();
}
else
{
i3 = new Implementation3(instances);
}
return i3;
}
}
在我的这些具体实现的工厂方法中，可以使用任何构造函数来创建具体实现。在示例中，useEmptyConstructor参数控制要使用的构造函数。其他工厂方法具有类似的功能。我记得读过，虽然我无法立即找到链接，但这些工厂方法应该允许在每种可能的配置中创建对象。
答案 0 :(得分：1)
您是否尝试使用[PexUseType]属性告诉Pex，您的抽象类的非抽象子类型是否存在？如果Pex不知道任何非抽象子类型，那么Pex的约束求解器将确定依赖于非抽象子类型存在的代码路径是不可行的。