public void NotEquals()
        {
            var sut = new B1(new D1());
            var other = new B1(Mock.Of<D1>());

            sut.Should().NotBe(other);
        }
        public void Equals()
        {
            var sut = new B1(new D1());
            var other = new B1(new D1());

            sut.Should().Be(other);
        }