TDD MVVM Framework Test Plan

Just out of interest, I was experimenting with TDDing (if that’s a real phrase) a basic MVVM framework in C#. The following is the rough sequence of tests for test-driving the implementation that I ended up using.

WPF makes use of two main interfaces: INotifyPropertyChanged for notifying the UI of updates to properties that it is bound to, e.g. the value in a TextBox; and ICommand for executing commands when, e.g. a Button is pressed.

Here are the sequence of tests for the two main classes in the framework.

ObservableObject : INotifyPropertyChanged

1. ObservableObject implements INotifyPropertyChanged
2. RaisePropertyChangedEvent with property name fires event
3. RaisePropertyChangedEvent with property name passes name through to handler
4. RaisePropertyChangedEvent with name of non-existent property throws ArgumentException (in Debug only)
5. RaisePropertyChangedEvent with multiple property names fires event for each
6. RaisePropertyChangedEvent with no observers does not throw exception

DelegateCommand : ICommand

1. DelegateCommand implements ICommand
2. CanExecute returns True
3. Execute runs stored Action
4. Execute with null does not throw exception

I’m unsure as to the necessity of testing that the classes implement the required interfaces but it is technically a requirement of the implementation.

At some point in the near future, I hope to record a video of this development.