c# - 从一般类型的实例调用 ToString 覆盖

Question

我正在为一些现有代码添加一些测试覆盖率。大约有 20 个类——都是同一基类的派生类——这将导致非常相似和重复的测试方法。相反，我试图做的是创建一个抽象测试类，它公开一些抽象方法来处理被测派生类的独特细节。

在我开始测试 ToString 覆盖之前，它一直运行良好。基本上，测试方法(您会记得它存在于抽象基类中)断言预期字符串值与在上述抽象提供的我的泛型实例上执行的 ToString 方法的结果相等方法。但是，并没有像我预期的那样调用 ToString 覆盖，而是调用标准对象实现，返回对象的完全限定名称。

那么，问题是:在处理一般类型的实例时，如何调用类的 ToString 重写？

我希望通过更好地理解泛型类型的基础知识来回答这个问题，因此，为了简洁起见，我不会发布任何代码。如果我低估了情况，请告诉我，我会添加相关代码。

提前致谢!

编辑 ==> 代码 :)

public abstract class KeyTestsBase<TKey, TKeyInterface> 
    where TKeyInterface : class
    where TKey : class, IKeyParser<TKey>
{
    protected readonly Mock<TKeyInterface> MockKey = new Mock<TKeyInterface>();

    protected abstract string ExpectedStringValue { get; }

    [Test]
    public void ToString_produces_correct_string_value()
    {
        // Arrange
        SetUpValidMock();

        // Act
        var key = BuildKey(MockKey.Object);

        var keyValue = BuildKey(MockKey.Object).ToString();

        // Assert
        Assert.AreEqual(ExpectedStringValue, keyValue);
    }

    protected abstract void SetUpValidMock();

    protected abstract TKey BuildKey(TKeyInterface keyInterface);
}

[TestFixture]
public class AdditiveProductKeyTests : KeyTestsBase<AdditiveProductKey, IAdditiveProductKey>
{
    private const int VALID_PRODUCT_KEY = 123;
    private const string VALID_PRODUCT_KEY_STRING = "123";
    private const string VALID_PARSE_INPUT = "123";

    #region Overrides of KeyTestsBase<AdditiveProductKey,IAdditiveProductKey>

    protected override string ExpectedStringValue
    {
        get { return VALID_PRODUCT_KEY_STRING; }
    }

    protected override void SetUpValidMock()
    {
        MockKey.SetupGet(m => m.AdditiveProductKey_Id).Returns(VALID_PRODUCT_KEY);
    }

    protected override AdditiveProductKey BuildKey(IAdditiveProductKey keyInterface)
    {
        return new AdditiveProductKey(keyInterface);
    }

    #endregion
}

这是许多 Key 类之一的示例，与@Marc 的怀疑相反，您会注意到 ToString 方法被覆盖了。

public class AdditiveProductKey : KeyBaseClass<AdditiveProductKey>, IKey<AdditiveProduct>, IAdditiveProductKey
{
    #region constructors and fields

    private readonly int _id;

    public AdditiveProductKey() : this(0) { }

    public AdditiveProductKey(IAdditiveProductKey additiveProductKey)
        :this(additiveProductKey.AdditiveProductKey_Id) { }

    private AdditiveProductKey(int id)
    {
        _id = id;
    }

    #endregion

    public Expression<Func<AdditiveProduct, bool>> FindByPredicate
    {
        get { return (p => p.Id == _id); }
    }

    protected override AdditiveProductKey ParseImplementation(string keyValue)
    {
        var id = int.Parse(keyValue);
        return new AdditiveProductKey(id);
    }

    protected override string GetParseFailMessageImplementation()
    {
        return UserMessages.InvalidAdditiveProductKey;
    }

    public override string ToString()
    {
        return AdditiveProductKey_Id.ToString(CultureInfo.InvariantCulture);
    }

    #region Implementation of IAdditiveProductKey

    public int AdditiveProductKey_Id { get { return _id; }}

    #endregion
}

这是 ToString_produces_correct_string_value 测试中变量 'key' 的类型信息。

key.GetType()
{Name = "AdditiveProductKey" FullName = "RioValleyChili.Data.Utilities.Keys.AdditiveProductKey"}
[System.RuntimeType]: {Name = "AdditiveProductKey" FullName = "RioValleyChili.Data.Utilities.Keys.AdditiveProductKey"}
base {System.Reflection.MemberInfo}: {Name = "AdditiveProductKey" FullName = "RioValleyChili.Data.Utilities.Keys.AdditiveProductKey"}
Assembly: {RioValleyChili.Data.Utilities, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null}
AssemblyQualifiedName: "RioValleyChili.Data.Utilities.Keys.AdditiveProductKey, RioValleyChili.Data.Utilities, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null"
Attributes: Public | BeforeFieldInit
BaseType: {Name = "KeyBaseClass`1" FullName = "RioValleyChili.Business.Core.Keys.KeyBaseClass`1[[RioValleyChili.Data.Utilities.Keys.AdditiveProductKey, RioValleyChili.Data.Utilities, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]]"}
ContainsGenericParameters: false
DeclaringMethod: 'key.GetType().DeclaringMethod' threw an exception of type 'System.InvalidOperationException'
DeclaringType: null
FullName: "RioValleyChili.Data.Utilities.Keys.AdditiveProductKey"
GenericParameterAttributes: 'key.GetType().GenericParameterAttributes' threw an exception of type 'System.InvalidOperationException'
GenericParameterPosition: 'key.GetType().GenericParameterPosition' threw an exception of type 'System.InvalidOperationException'
GenericTypeArguments: {System.Type[0]}
GUID: {81e8adb0-f899-358b-aa20-9bec8f96666d}
HasElementType: false
IsAbstract: false
IsAnsiClass: true
IsArray: false
IsAutoClass: false
IsAutoLayout: true
IsByRef: false
IsClass: true
IsCOMObject: false
IsConstructedGenericType: false
IsContextful: false
IsEnum: false
IsExplicitLayout: false
IsGenericParameter: false
IsGenericType: false
IsGenericTypeDefinition: false
IsImport: false
IsInterface: false
IsLayoutSequential: false
IsMarshalByRef: false
IsNested: false
IsNestedAssembly: false
IsNestedFamANDAssem: false
IsNestedFamily: false
IsNestedFamORAssem: false
IsNestedPrivate: false
IsNestedPublic: false
IsNotPublic: false
IsPointer: false
IsPrimitive: false
IsPublic: true
IsSealed: false
IsSecurityCritical: true
IsSecuritySafeCritical: false
IsSecurityTransparent: false
IsSerializable: false
IsSpecialName: false
IsUnicodeClass: false
IsValueType: false
IsVisible: true
MemberType: TypeInfo
Module: {RioValleyChili.Data.Utilities.dll}
Namespace: "RioValleyChili.Data.Utilities.Keys"
ReflectedType: null
StructLayoutAttribute: {System.Runtime.InteropServices.StructLayoutAttribute}
TypeHandle: {System.RuntimeTypeHandle}
TypeInitializer: null
UnderlyingSystemType: {Name = "AdditiveProductKey" FullName = "RioValleyChili.Data.Utilities.Keys.AdditiveProductKey"}

结果如下:

key.ToString() 
"RioValleyChili.Data.Utilities.Keys.AdditiveProductKey" //what i'm getting

((AdditiveProductKey)key).ToString()
"123" // what I'm expecting

Answer 1

ToString是一个虚拟/多态函数。只要你用过override它应该已经正常工作了。我怀疑你没有使用 override .

public override string ToString() {
   // ...
}

---

编辑:

这不一定在您认为的类中:可能是 KeyBaseClass<T>有一个 virtual ToString()而不是 override ToString() .这是一个无关 ToString - 所以你的override会作用于this，而不是object.ToString() .