public void Should_Fail_By_Empty_Id() { // arrange var command = PatchMemberCommandFake.LeaveGuildInvalidByEmptyId().Generate(); var memberRepository = MemberRepositoryMockBuilder.Create().Build(); var sut = new LeaveGuildValidator(memberRepository) { CascadeMode = FluentValidation.CascadeMode.Stop }; // act var result = sut.Validate(command); // assert result.AssertErrorsCount(1); }