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https://github.com/hjerpbakk/notifypropertychanged.verifier
A fluent extension of xUnit for testing implementations of INotifyPropertyChanged in ViewModels.
https://github.com/hjerpbakk/notifypropertychanged.verifier
dotnet inotifypropertychanged testing uwp wpf xamarin-forms xunit
Last synced: about 1 month ago
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A fluent extension of xUnit for testing implementations of INotifyPropertyChanged in ViewModels.
- Host: GitHub
- URL: https://github.com/hjerpbakk/notifypropertychanged.verifier
- Owner: hjerpbakk
- License: mit
- Created: 2019-10-21T08:48:27.000Z (about 5 years ago)
- Default Branch: master
- Last Pushed: 2021-04-21T11:17:45.000Z (over 3 years ago)
- Last Synced: 2024-11-03T08:37:06.505Z (about 2 months ago)
- Topics: dotnet, inotifypropertychanged, testing, uwp, wpf, xamarin-forms, xunit
- Language: C#
- Homepage: https://hjerpbakk.com/blog/2019/10/25/inotifypropertychanged-verifier
- Size: 91.8 KB
- Stars: 5
- Watchers: 3
- Forks: 0
- Open Issues: 4
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# NotifyPropertyChanged.Verifier
Introducing [NotifyPropertyChanged.Verifier](https://www.nuget.org/packages/NotifyPropertyChanged.Verifier/), a fluent extension of xUnit for testing implementations of INotifyPropertyChanged in ViewModels.
[](https://github.com/Sankra/NotifyPropertyChanged.Verifier/actions) [](https://codecov.io/gh/Sankra/NotifyPropertyChanged.Verifier) [](https://www.nuget.org/packages/NotifyPropertyChanged.Verifier) [](https://www.nuget.org/packages/NotifyPropertyChanged.Verifier)
## tl;dr
```csharp
vm.ShouldNotifyOn(vm => vm.PropertyWithNotify)
.When(vm => vm.PropertyWithNotify = 42);
vm.ShouldNotNotifyOn(vm => vm.PropertyWithoutNotify)
.When(vm => vm.PropertyWithoutNotify = -1);
```
## Usage
Consider the following ViewModel:
```csharp
public class ViewModel : INotifyPropertyChanged {
int backingField;
string backingField2;
public int PropertyWithoutNotify { get; set; }
public int PropertyWithNotify {
get => backingField;
set {
backingField = value;
OnPropertyChanged();
}
}
public string PropertyWithMultipleNotifies {
get => backingField2;
set {
PropertyWithNotify = int.Parse(value);
OnPropertyChanged();
}
}
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged([CallerMemberName] string propertyName = "") =>
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
```
To test it, create an xUnit-test project and add a NuGet reference to [NotifyPropertyChanged.Verifier](https://www.nuget.org/packages/NotifyPropertyChanged.Verifier/). It's a .Net Standard 2.0 library and can be used both in .Net Core and the full .NET Framework. The preceding ViewModel can test its implementation of INotifyPropertyChanged doing:
```csharp
using NotifyPropertyChanged.Verifier;
using Xunit;
namespace Tests {
public class UnitTests {
readonly ViewModel vm;
public UnitTests() => vm = new ViewModel();
[Fact]
public void PropertyWithNotify_WillRaiseNotifyEvent() =>
vm.ShouldNotifyOn(vm => vm.PropertyWithNotify)
.When(vm => vm.PropertyWithNotify = 42);
[Fact]
public void PropertyWithoutNotify_WillNotRaiseNotifyEvent() =>
vm.ShouldNotNotifyOn(vm => vm.PropertyWithoutNotify)
.When(vm => vm.PropertyWithoutNotify = -1);
[Fact]
public void PropertyWithMultipleNotifies_WillRaiseMultipleNotifyEvents() =>
vm.ShouldNotNotifyOn(vm => vm.PropertyWithNotify,
vm => vm.PropertyWithMultipleNotifies)
.When(vm => vm.PropertyWithMultipleNotifies = "42");
}
}
```
The library consists of two extension methods on INotifyPropertyChanged, `ShouldNotifyOn` and `ShouldNotNotifyOn` which takes 1 or more property expressions as input. These are the properties that should either receive or not receive a NotifyPropertyChanged-event when an `Action` is called by the `When` method. This can anything, not only methods or properties on the ViewModel itself.
Inspired by this [blogpost](https://blog.ploeh.dk/2009/08/06/AFluentInterfaceForTestingINotifyPropertyChanged/).