Moq Verify events triggered

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class A
{
    event EventHandler Event1;
}
var mock = new Mock<A>();

How do I verify Event1 was fired? (without using manual event handlers / triggered flags)

3 Answers

How about something like this?

public class MyClass : INotifyPropertyChanged
{
    private string _name;
    public string Name
    {
        get => _name;

        set
        {
            _name = value;
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(Name)));
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
}

In your tests:

// This interface contains signatures which match your event delegates
public interface IPropertyChangedEventHandler
{
    void PropertyChangedHandler(object sender, PropertyChangedEventArgs e);
}

public void WhenSettingNameNotifyPropertyChangedShouldBeTriggered()
{
    // Arrange
    var sut = new Mock<MyClass>();

    var handler = new Mock<IPropertyChangedEventHandler>();
    handler.Setup(o => o.PropertyChangedHandler(sut, new PropertyChangedEventArgs(nameof(MyClass.Name))));

    sut.PropertyChanged += handlerMock.Object.PropertyChangedHandler;

    // Act
    sut.Name = "Guy Smiley";

    // Assert
    handler.Verify();
}
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