如何使用Moq模拟集合？

Question

我是全新的单元测试和嘲弄，仍然是湿背后的耳朵。我使用的是Moq框架，我需要模拟一个集合，这样它就产生了一个具有我提供的值的成员。

所讨论的集合类是System.Configuration.SettingsPropertyCollection，它包含SettingsProperty对象。

反过来，SettingsProperty有一个返回SettingsAttributeDictionary的Attributes属性。

我需要我的集合来生成一个SettingsProperty，它在其Attributes.SettingsAttributeDictionary中有一个自定义属性(从System.Attribute派生)。

我真的很难搞清楚这件事，但到目前为止还是没有用。我试着伸出舌头，对着它鬼鬼祟祟地做鬼脸，但都没有用。

下面是我已经尝试过的代码，在代码中注释的点会抛出一个异常，所以测试总是失败的。

    [TestMethod]
    public void GetPropertySettings_Should_Return_Default_Values_When_Device_Not_Registered()
        {
        const string deviceName = "My.UnitTest";
        const string deviceType = "Switch";
        var deviceId = String.Format("{0}.{1}", deviceName, deviceType);
        Mock<IProfile> mockProfile = new Mock<IProfile>();
        Mock<SettingsContext> mockSettingsContext = new Mock<SettingsContext>();
        // Construct a SettingsPropertyCollection populated with a single property.
        // The single property will have a fixed name and default value, and will also have a single
        // attribute, giving teh ASCOM DeviceId.
        var deviceAttribute = new ASCOM.DeviceIdAttribute(deviceId);
        var attributes = new SettingsAttributeDictionary();
        attributes.Add(typeof(DeviceIdAttribute), deviceAttribute);
        var settingsProperty = new SettingsProperty(SettingName, typeof(string), null, false, SettingDefaultValue, SettingsSerializeAs.String, attributes, true, true);
        var propertyCollection = new SettingsPropertyCollection();
        propertyCollection.Add(settingsProperty);

        // Now comes the interesting part where we call our IProfile - this is where we really need Moq.
        // Expectations:
        //  - mockProfile must have it's DeviceType set.
        //  - mockProfile's device type (captured in setDeviceType) must match deviceType.
        //  - The returned SettingsPropertyValueCollection must not be empty.
        //  - The returned SettingsPropertyValueCollection must have exactly one entry.
        //  - The entry must match the value of SettingDefaultValue. 

        // Expectation: IProfile must have its DeviceType set.  We capture the value into setDeviceType.
        var setDeviceType = String.Empty;
        mockProfile.SetupSet(x => x.DeviceType).Callback(y => setDeviceType = y);

        // Finally, it is time to call the method we want to test
        var settingsProvider = new SettingsProvider(mockProfile.Object);

        // THE NEXT LINE THROWS AN EXCEPTION
        // IF I TRY TO STEP INTO IT, IT NEVER RETURNS AND THE TEST RUN JUST ENDS.
        var result = settingsProvider.GetPropertyValues(mockSettingsContext.Object, propertyCollection);

        // Now lets verify that everything went as expected
        // First, let's test that the parsing of DeviceId was as expected: IProvider.DeviceType was set to the expected value
        Assert.AreEqual(deviceType, setDeviceType);
        // Then let's test that the methods of IProvider that we mocked were called
        mockProfile.VerifyAll();

        // With this done, let's turn to the output of the method
        // Firstly, we test that the resulting collection contains exactly one item of the type SettingsPropertyValue
        Assert.IsTrue(result.Count > 0);
        Assert.AreEqual(1, result.Count);
        Assert.IsTrue(result.OfType<SettingsPropertyValue>().Count() > 0);

        // Then let's inspect the contained SettingsProviderValue further
        var settingsPropertyValue = result.OfType<SettingsPropertyValue>().First();

        // First IsDirty flag must never be set
        Assert.IsFalse(settingsPropertyValue.IsDirty);

        // The PropertyValue must be the default value we passed in
        Assert.AreEqual(SettingDefaultValue, settingsPropertyValue.PropertyValue);
        }

抛出的异常(正如测试运行程序所报告的)是：

ASCOM.Platform.Test.SettingsProviderTest.GetPropertySettings_Should_Return_Default_Values_When_Device_Not_Registered抛出异常: System.ArgumentException:类型System.Configuration.SettingsContext实现ISerializable，但未能提供反序列化构造函数.

Answer 1

我相信您需要设置模拟SettingsProperty的属性以返回模拟SettingsAttributeDictionary和，然后设置模拟SettingsAttributeDictionary的索引器以返回所需的值。

mockItem.SetupGet(x => x.Attributes).Returns(mockAttributes);

mockAttributes.SetupGet(x => x[It.IsAny<System.Type>()])
              .Returns(deviceAttribute);

编辑

异常将被抛出在由Moq使用的Castle类中。我相信这与Moq如何模拟可序列化的对象有关。如果在可序列化对象上找不到具有(SerializationInfo，StreamingContext)签名的非公共构造函数，那么它将抛出此异常。您可以做的是更改自定义SettingsProvider的SettingsProvider方法，以便它接受一个哈希表而不是一个SettingsContext，并为方法调用提供一个模拟哈希表而不是一个模拟SettingsContext。Hashtable有所需的构造函数，所以这可能会起作用。坚持使用类型为SettingsContext而不是Hashtable的参数并没有什么真正的好处，因为SettingsContext只是从Hashtable派生出来的，也就是说它没有添加任何成员。