CODEWITHSUNDEEP
asp.netunit-testingnunitfluentvalidation
Frederik
Frederik

Reputation: 667

Asp.net FluentValidation unit testing object as null

I'm doing some unit testing using FluentValidation in Asp.net. I have setup a rule stating that an object is not allowed to be null, as it's going to be used as an argument in a method. The rule is made in a validator-class in the constructor: 

 //Object itself.
 RuleFor(x => x).NotNull();

The unit test looks like (I'm using NUnit):

[Test]
public void RequestObjectIsNull_ExpectError()
{
    BusinessRequest request = null;
    var result = validator.Validate(request);

    Assert.IsFalse(result.IsValid);
}

It fails with the message:

Message: System.ArgumentNullException : Cannot pass null model to Validate. Parameter name: instanceToValidate

How do I test this?

Upvotes: 3

Views: 2549

Answers (1)

vsarunov
vsarunov

Reputation: 1547

This question is quite old but I have stumbled upon the same issue. I wanted the fluent validator to validate it for me if it is null and say so and not throw an exception, instead of me explicitly checking for it. I have found a solution of overriding the existing methods, For example:

 public class MyValidator : AbstractValidator<MyObject>
    {
        public MyValidator()
        {
            RuleSet("MyRule", () =>
            {
                RuleFor(x=>x.MyProperty=="Something").WithMessage("failed");
            });
        }

        public override Task<ValidationResult> ValidateAsync(ValidationContext<MyObjec>> context, CancellationToken cancellation = default)
        {
            return context.InstanceToValidate == null ? Task.FromResult(new ValidationResult(new[] { new ValidationFailure("MyObject", "filed with null") })) : base.ValidateAsync(context, cancellation);
        }
    }

Upvotes: 2

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