使用 Moq 模拟通用、动态接口答案

【问题标题】：Mock generic, dynamic interface with Moq使用 Moq 模拟通用、动态接口
【发布时间】：2014-03-18 23:03:42
【问题描述】：

我有以下界面可以模拟出来：

internal interface IRenderer
{
    void Render<T>(StringWriter stringWriter, T item) where T : struct;

    void Render(StringWriter stringWriter, decimal item);

    void Render(StringWriter stringWriter, string item);
}

还有一个测试如下：

[Test]
[TestCase("dummy-string", "dummy-string")]
[TestCase(123, "123")]
[TestCase(123.456, "123.456")]
[TestCase(true, "True")]
[TestCase('C', "C")]
public void RendersExpectedValues(dynamic item, string rendered)
{
    // Do some stuff
    using (var stringWriter = new StringWriter(renderedBuilder)
    {
        _mockRenderer.Setup(x => x.Render(textWriter, item));
        _renderer.Render(textWriter, item);
    }

   Assert.It.Worked();
}

如您所见，item 是dynamic，过载是在运行时确定的...我玩过

Type type = item.GetType();
_mockRenderer.Setup(x => x.Render<type>(textWriter, item));

和

Type type = item.GetType();
_mockRenderer.Setup(x => x.Render<typeof(type)>(textWriter, item));

两者都不起作用（当然）。

这可能吗？我可以将字符串测试用例删除到单独的测试中。

【问题讨论】：

标签： .net dynamic moq

【解决方案1】：

我不认为有直接的解决方法——我总是明白：

错误：表达式树可能不包含动态操作`

尝试在设置中使用dynamic 时。 AFAIK 您需要对每种支持的类型执行明确的Setup()s。

但是，您可以稍微干一下，但是使用通用设置辅助方法，例如：

   static class Helpers
   {
      public static Mock<IRenderer> Setup<T>(this Mock<IRenderer> mockRenderer) where T : struct
      {
         mockRenderer.Setup(x => x.Render(It.IsAny<StringWriter>(), It.IsAny<T>()))
            .Callback<StringWriter, T>((sw, s) => sw.Write(s));
         return mockRenderer;
      }
   }

然后可以设置 + 调用：

  [Test]
  [TestCase("dummy-string",  "dummy-string")]
  [TestCase(123, "123")]
  [TestCase(123.456, "123.456")]
  [TestCase(true, "True")]
  public void RendersExpectedValuesString(dynamic item, string rendered)
  {
     var _mockRenderer = new Mock<IRenderer>()
        .Setup<double>()
        .Setup<bool>()
        .Setup<int>()
        .Setup<decimal>();
     _mockRenderer.Setup(x => x.Render(It.IsAny<StringWriter>(), It.IsAny<string>()))
        .Callback<StringWriter, string>((sw, s) => sw.Write(s));

     var renderedBuilder = new StringBuilder();
     var sut = new SomethingWhichUsesRenderer(_mockRenderer.Object);

      // Do some stuff
      using (var stringWriter = new StringWriter(renderedBuilder))
      {
        sut.DoSomething(stringWriter, item);

        // This obviously just tests the Mock ...
        Assert.AreEqual(renderedBuilder.ToString(), rendered);

        // Do actual unit tests + Mock.Verifies here
      }
  }

【讨论】：