Question

在earlier question我询问了Autofixture CreateProxy method时，确定了potential bug。

我不认为这次失败的测试是由于这一点，而是我对Likeness.Without（...）。CreateProxy（）语法如何工作的持续混淆。考虑以下失败测试，我通过创建对象的新实例使original test 变得更加复杂，将其创建视为SUT：

[Fact]
public void Equality_Behaves_As_Expected()
{
    // arrange: intent -> use the fixture-created Band as Object Mother
    var template = new Fixture().Create<Band>();

    // act: intent -> instantiated Band *is* the SUT
    var createdBand = new Band {Brass = template.Brass,
                                Strings = template.Brass};

    //   intent -> specify that .Brass should not be considered in comparison 
    var likeness = template.AsSource().OfLikeness<Band>().
        Without(x => x.Brass).CreateProxy(); // Ignore .Brass property

    // per [https://stackoverflow.com/a/15476108/533958] explicity assign
    // properties to likeness
    likeness.Strings = template.Strings;
    likeness.Brass = "foo"; // should be ignored

    // assert: intent -> check equality between created Band & template Band
    //         to include all members not excluded in likeness definition
    likeness.Should().Be(createdBand);          // Fails
    likeness.ShouldBeEquivalentTo(createdBand); // Fails
    Assert.True(likeness.Equals(createdBand));  // Fails
}

以下是乐队：

public class Band
{
    public string Strings { get; set; }
    public string Brass { get; set; }
}

我的earlier question并不够复杂，无法帮助我了解Source Likeness应该是什么。

源是否应该是SUT的输出，在这种情况下，它将与AutoFixture创建的模板实例进行比较？

或者源是否是AutoFixture创建的模板实例，在这种情况下，它会与SUT的输出进行比较？

编辑：更正了测试中的错误

我意识到我错误地将template.Brass属性分配给 Brass 和新Strings属性Band个实例。更新的测试反映了var createdBand = new Band {Brass = template.Brass, Strings = template.Strings}的更正，现在所有六个断言都已通过。

[Fact]
public void Equality_Behaves_As_Expected()
{
    // arrange: intent -> use the fixture-created Band as Object Mother
    var template = new Fixture().Create<Band>();

    // act: intent -> instantiated Band *is* the SUT
    var createdBand = new Band {Brass = template.Brass, Strings = template.Strings};

    // likeness of created
    var createdLikeness = createdBand.AsSource().OfLikeness<Band>().
        Without(x => x.Brass).CreateProxy(); // .Brass should not be considered in comparison 

    // https://stackoverflow.com/a/15476108/533958 (explicity assign properties to likeness)
    createdLikeness.Strings = createdBand.Strings;
    createdLikeness.Brass = "foo"; // should be ignored

    // likeness of template
    var templateLikeness = template.AsSource().OfLikeness<Band>()
        .Without(x => x.Brass)
        .CreateProxy();
    templateLikeness.Strings = template.Strings;
    templateLikeness.Brass = "foo";

    // assert: intent -> compare created Band to template Band
    createdLikeness.Should().Be(template);
    createdLikeness.ShouldBeEquivalentTo(template);
    Assert.True(createdLikeness.Equals(template));

    templateLikeness.Should().Be(createdBand);
    templateLikeness.ShouldBeEquivalentTo(createdBand);
    Assert.True(templateLikeness.Equals(createdBand));
}

Answer 1

你的意思是：

likeness.Should().BeAssignableTo<Band>(); // Returns true.

在提供的示例中，从Likeness生成的代理是从Band派生的类型，使用语义比较算法覆盖Equals。

使用反射：

createdBand.GetType().IsAssignableFrom(likeness.GetType()) // Returns true.

<强>更新：

createBand 和模板实例不受CreateProxy方法的影响。他们为什么要这样做？

凭借相似CreateProxy，您基本上可以创建一个允许您执行的Custom Equality Assertion：

Assert.True(likeness.Equals(createdBand)); // Passed.

没有它，最初的Equality Assertion将会失败：

Assert.True(template.Equals(createdBand)); // Failed.

但是，以下内容也将失败：

Assert.True(likeness.Equals(template));

失败是因为Strings值是 createdBand 实例中的值。

此行为是预期的，您可以直接使用Likeness验证它：

 createdBand.AsSource().OfLikeness<Band>()
     .Without(x => x.Brass).ShouldEqual(template);

输出：

 The provided value `Band` did not match the expected value `Band`. The following members did not match:
      - Strings.

使用Autofixture的CreateProxy来使用Likeness，SemanticComparison功能时遇到麻烦

1 个答案: