CallbackAssertion for FluentAssertions

CallbackAssertion.cs

    public class CallbackAssertion
    {
        private int _calls;
        private readonly Action _call;

        public CallbackAssertion()
        {
            _call = () => _calls++;
        }

        public static implicit operator Action(CallbackAssertion callbackAssertion)
        {
            return callbackAssertion._call;
        }

        public void ShouldBeCalledOnce()
        {
            _calls.Should().Be(1);
        }

        public void ShouldNotBeCalled()
        {
            _calls.Should().Be(0);
        }

        public void ShouldBeCalled(int times)
        {
            _calls.Should().Be(times);
        }
    }