具有子/子类的类的单元测试 FluentValidation 规则

Question

Is it possible to write unit tests for fluentvalidation classes when the object we are validating has child classes that are also being validated.

As an example: My class looks like this

public class TestModel
{

    public class SubData
    {
        public int SubDataVal { get; set; }
    }

    public int ParentVal { get; set; }
    public SubData Sub { get; set; }

}

My validation logic looks like this:

public class TestModelValidator : AbstractValidator<TestModel>
{
    public TestModelValidator()
    {
        RuleFor(o => o.ParentVal).GreaterThan(0);
        RuleFor(o => o.Sub.SubDataVal).GreaterThan(0);
    }
}

And when I write the following unit test

    [Test]
    public void Should_have_error_when_val_is_zero()
    {
        validator = new TestModelValidator();
        validator.ShouldHaveValidationErrorFor(model => model.ParentVal, 0);
    }

I get a "System.NullReferenceException : Object reference not set to an instance of an object." exception from FluentValidation.TestHelper.ValidatorTester`2.ValidateError(T instanceToValidate)

(if I remove the RuleFor(o => o.Sub.SubDataVal).GreaterThan(0); line, then it works!)

Similarly if I try and unit test the actual child class with:

    [Test]
    public void Should_have_error_when_sub_dataVal_is_zero()
    {
        validator = new TestModelValidator();
        validator.ShouldHaveValidationErrorFor(model => model.Sub.SubDataVal, 0);
    }

I get a "System.Reflection.TargetException : Object does not match target type." from FluentValidation.TestHelper.ValidatorTester`2.ValidateError(T instanceToValidate)

Answer 1

You can unit test models and child models but you will need to change your validation class to use a separate validator class which just validates the child model:

public class TestModelValidator : AbstractValidator<TestModel>
{
    public TestModelValidator()
    {
        RuleFor(o => o.ParentVal).GreaterThan(0);
        RuleFor(o => o.Sub).SetValidator(new SubDataValidator());
    }
}

public class SubDataValidator : AbstractValidator<SubData>
{
    public SubDataValidator()
    {
        RuleFor(o => o.SubDataVal).GreaterThan(0);
    }
}

You can then write your unit tests to test each validator or both together.

Answer 2

I have come to the conclusion that for this ShouldHaveValidationErrorFor is just not capabable of dealing with subclasses, so have resorted to doing it manually. ie

    [Test]
    public void Should_have_error_when_val_is_zero()
    {
        validator = new TestModelValidator();
        TestModel testRequest = new TestModel();
        //populate with dummy data
        var result = validator.Validate(testRequest);
        Assert.That(result.Errors.Any(o => o.PropertyName== "ParentVal"));
    }

Answer 3

With MSTest and FluentAssertions you can write

[TestMethod]
public void Should_have_error_when_val_is_zero()
{
    // Given
    var validator = new TestModelValidator();
    var testModel = TestModel
    {
        ParentVal = 0
    }; // You should create a invalid TestModel object here

    // When
    validator.Validate(testModel).IsValid.Should().BeFalse();
}