Specify desired amount of items when configuring a customization

Hi,

I’m trying to test a piece of code that is sensible to the amount of items in a given set. Unluckily, I really can’t avoid passing proper data to activate a specific path.

I would normally use CreateMany<T>(int) to specify the amount of items I need, but the set is in a property of a container object (btw, I am addicted to the new relay for IReadOnlyList<T>) like

public class ContactIdList
{
    [JsonProperty("vids")]
    public IReadOnlyList<long> ContactIds { get; set; }

    [JsonProperty("vidOffset")]
    public long? Offset { get; set; }

    [JsonProperty("hasMore")]
    public bool HasMore { get; set; }
}

What I would suggest is to offer a way to specify the amount of items needed to be generated when customizing a type.

Ideally, something like this

var list = fixture.Build<ContactIdList>()
                  .With(p => p.HasMore, false)
                  .Without(p => p.Offset)
                  .WithMany(p => p.ContactIds, 16)
                  .Create();

The parameters should be something like (Expression<Func<T, IEnumerable<TProperty>> propertyPicker, int count) but I’m honestly torn between naming it WithMany<TProperty> and adding another overload of With<TProperty>.

Obviously, I’m aware that I can create the list before and use With<TProperty>(Expression<Func<T, TProperty> propertyPicker, TProperty value) to pass the list.

[zvirja]

Agreed 😉 Converting this to a potential feature.

[zvirja]

Thanks for raising the scenario.

I do understand the scenario you have, however I don’t like too much the suggested way to fix it. The scenario looks very specific to extend API for it.

Instead, it’s much better to implement it as a part of the #708. If we add the With() method overload taking the factory method, so it can be solved like this:

fixture.Customize<ClassToCustomize>(c =>
    c.With(x => x.Values, () => fixture.CreateMany<int>(25).ToList())
);

This solution is way more generic as behavior is not limited to collections only.

@moodmosaic I’d be really happy to implement #708 as it’s a real enabler for more specific scenario. Therefore, if you accept such a PR, I could implement it 😉