WPF - XamlParseException when unit testing method in Window class

Question

I'm trying to use MSTest to write unit tests for methods in my MainWindow class in my WPF application. However, I get the following exception:

System.Windows.Markup.XamlParseException: 'Provide value on 'System.Windows.StaticResourceExtension' threw an exception.' Line number '127' and line position '32'. ---> System.Exception: Cannot find resource named 'verticalLineStyle'. Resource names are case sensitive.

verticalLineStyle is found in a ResourceDictionary that is included in App.xaml. I have no need of this style to test the method I'm trying to test, but I can't get past this. I'm just creating a new instance of MainWindow in my unit test and trying to call an instance method on that. The exception occurs when I try to create the instance of MainWindow. MainWindow is defined as public partial class MainWindow : Window.

How do I get rid of this error? Is there some preferred way of unit testing methods in windows in WPF applications?

Answer 1

Application.LoadComponent(
    new Uri("/MyAppAssemblyName;component/App.xaml", UriKind.Relative));

This helped me.