Use DataTemplate in WPF with a mocked object

I have following xaml code:

<Window x:Class="MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        DataContext="{Binding MainWindow, Source={StaticResource Loc开发者_运维知识库ator}}">

    <Window.Resources>
        <DataTemplate DataType="{x:Type vm:KeyboardViewModel}">
            <vw:Keyboard />
        </DataTemplate>
        <DataTemplate DataType="{x:Type vm:WelcomeViewModel}">
            <vw:Welcome />
        </DataTemplate>


    </Window.Resources>
    <DockPanel>
        <DockPanel>
            <ContentControl Content="{Binding Path=Workspace}" />
        </DockPanel>
    </DockPanel>
</Window>

When Workspace is KeyboardViewModel, then the UserControl Keyboard is shown. When Workspace is Welcome, then the Welcome screen is shown. But when I test I mock the ViewModels with Moq. Workspace then get the type IKeyboardViewModelProxyxxxxxxxxxxxxx (where xxxxxxx is a random string), that don't maps to KeyboardViewModel in the DataTemplate and WPF don't now wish DataTemplate to show. When I use the real KeyboardViewModel, it is no problem. Can I fix it somehow, or do I have to redesign it?

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I'm having a similar issue (without using Moq however). A PARTIAL solution that I used is to inherit both KeyboardViewModel and KeyboardViewModelMock from abstract KeyboardViewModelAbstract. Then you can do:

<DataTemplate DataType="{x:Type vm:KeyboardViewModelAbstract}">
    <vw:Keyboard />
</DataTemplate>

Which will work for both, the real model object and the mock.

Unfortunately this solution doesn't scale when you're dealing with models that already have a base class or have any kind of inheritance involved. I'd be great if DataTemplate could be used with interfaces, but they can't.

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You can omit the DataType="{x:Type vm:KeyboardViewModel}". If you do that, it is not expecting an instance of type KeyboardViewModel to bind against anymore but only an object of any type that just has all properties that are used in the template.