public void RfidReader_event_OnRfidDetected() { //Arrange int numValues = 0; _uut.RfidEvent += (o, args) => numValues++; //Act _uut.onRfidRead(123); _uut.onRfidRead(123); _uut.onRfidRead(123); //Assert Assert.That(numValues, Is.EqualTo(3)); }