RuleForEach.SetValidator ignores when clause

System Details

• FluentValidation version: 8.4.0

Issue Description

Steps to reproduce

Use the following rule in an AbstractValidator

RuleForEach(p => p)
    .SetValidator(c => new CustomValidator())
    .When(p => false);

Expected behaviour The rule does not run, as the when will always evaluate to false.

Actual behaviour The rule runs.

---

Complete Example

public class ClassA
{
    public ClassB OptionalProperty { get; set; }
}

public class ClassB
{
    public List<ClassC> Collection { get; set; }
}

public class ClassC
{
    public string Name { get; set; }
}

public class ClassAValidator : AbstractValidator<ClassA>
{
    public ClassAValidator()
    {
        // Correct behaviour. Generates a deprecated warning
        RuleFor(p => p.OptionalProperty.Collection)
            .SetCollectionValidator(c => new ClassCValidator())
            .When(p => p.OptionalProperty != null);

        // Blows up- NullReferenceException
        RuleForEach(p => p.OptionalProperty.Collection)
            .SetValidator(c => new ClassCValidator())
            .When(p => p.OptionalProperty != null);
    }
}

public class ClassCValidator : AbstractValidator<ClassC>
{
    public ClassCValidator()
    {
        RuleFor(c => c.Name).MaximumLength(20);
    }
}

[JeremySkinner]

Also, I think that the behaviour isn’t particularly intutive, so I’ll think about changing this so that calls to When do run outside the loop (we already have the Where method for filtering elements inside the loop), but I need to do some testing to see if this would be a breaking change.

[BadgerCode]

Excellent. Thank you!