public void CanValidateRequiredObject() { StringBuilder emptyStringBuilder = null; var instanceOfStringBuilder = new StringBuilder(); CustomAssert.ThrowsWithExceptionMessage<BusinessRuleViolationException>(() => emptyStringBuilder.Required(), "StringBuilder is required"); CustomAssert.ThrowsWithExceptionMessage<BusinessRuleViolationException>(() => emptyStringBuilder.Required("This value is required"), "This value is required"); Assert.DoesNotThrow(() => instanceOfStringBuilder.Required()); }