SampleWpfApplicationTests

Unit testing WPF bindings

This project demonstrates how to test WPF binding errors in MSTest.

In this project, I use BindingErrorListener, a class that raises an event each time a WPF binding error occurs.

[TestMethod]
public void MainWindow_HasNoBindingError()
{
    using( var listener = new BindingErrorListener())
    {
        listener.ErrorCatched += msg => Assert.Fail(msg);

        new MainWindow();
    }            
}

As shown in the screen-shot, the test fails as expected because there is a bad binding in MainWindow.xaml.

By examining the exception message, we can find the exact binding causing the error:

BindingExpression path error: 'BadBinding' property not found on 'object' ''MainWindowViewModel' (HashCode=30488660)'.

BindingExpression:Path=BadBinding; 
DataItem='MainWindowViewModel' (HashCode=30488660);
target element is 'Label' (Name='');
target property is 'Content' (type 'Object')