Add collection .IfAny() .IfSingle() .IfNotSingle() .IfNone() .IfAll()

[amantinband]

Add the following collection validations:

var collection = new[] { 1, 2, 3, 3 };

collection.Throw().IfAny(item => item == 3);
collection.Throw().IfSingle(item => item == 2);
collection.Throw().IfNotSingle(item => item == 3);
collection.Throw().IfNone(item => item == 0);
collection.Throw().IfAll(item => item > 0);

[dwakel]

@mantinband
Just to clarify if single is when only one element in the collection is equal to 2
And not single is when more than one element is equal to 3

[dwakel]

I picked up this issue. Currently writing test.
This is probably my first open-source contribution ever
I've enjoyed working on this

[amantinband]

Awesome, that was quick! Let me know If you have any questions. Also, feel free to split this into multiple PRs if that would be more convenient 🙂

[dwakel]

@mantinband
should these extensions be able to evaluate any type.

Im assuming for
collection.Throw().IfAny(item => item == 3);
It should accept an expression which can evaluate
item => item > 3
item => item < 3
item => item <= 3
(Any inequality expression)

This however wont yield same results for a collection of strings unless a numeric property or function of the string (Count, Length, etc.) is Invoked

[amantinband]

I was thinking of something similar to this draft PR: #25
WDYT?

There is a C# language limitation that we cannot specify the method declaration as following:

    public static ref readonly Validatable<TValue> IfAny<TValue, TItem>(this in Validatable<TValue<TItem>> validatable, Func<TItem, bool> predicate, [CallerArgumentExpression("predicate")] string? predicateName = null)

Unfortunately in this implementation, we need to disambiguate the predicate's input parameter (int x in the draft PR). Couldn't find a way around this..

[amantinband]

@dwakel
Take a look at the latest iteration of #25. This works as you would expect. The only downfall is that it boxes the Validatable struct which will hurt performance. I wonder if there is a way around this

[dwakel]

@mantinband
I noticed the validatable doesn't return TCollectionType but just encapsulates an IEnumerable directly.
It also didn't occur to me that you could just pass the inequality condition as a Func<item,bool> 😄
The picture I had in my mind was to accept an Expression type then evaluate it using LINQ

[dwakel]

Should these operations be limited to a subset ⊆ of Rational numbers

[amantinband]

Nah, I think the main use case will be on complex objects and not on collections of rational numbers/strings

[dwakel]

I'm going to jump back to working on this issue

[SakuraIsayeki]

Hi there! Just jumping into the pool. Is the issue still being worked on? Or is it up for grabs?
I'm eager to contribute to this lib, so if there's anything I can add... Might as well start here ^^

[dwakel]

Hey @SakuraIsayeki you could definitely look at this issue.
Please also share any insights you have. It'll be nice knowing how you would go about implementing this

[SakuraIsayeki]

Okay. I see where the snag lies.

To recap, the current issue has us unable to determine IfAny()'s TElement on this example :

Action action = () => collection.Throw().IfAny(x => x == "ho");
Action action2 = () => collection2.Throw().IfAny(x => x == 1);

Where IfAny() is plagued with the same issue, namely The type arguments for method 'ref readonly Validatable<TValue> Throw.ValidatableExtensions.IfAny<TValue,TElement>(this in Validatable<TValue>, Expression<Func<TElement,bool>>)' cannot be inferred from the usage..

Here's what I have so far: SakuraIsayeki@7e87a42

This got me thinking...

How did they manage it on FluentAssertions?

FluentAssertions would have it as so:

collection.Should().Satisfy(x => x == "ho");
collection2.Should().Satisfy(x => x == 1);

And it just works. Here's the catch tho ; These buggers used IEnumerable<T> as the arg type on Should()! And honestly this is briliant. They're essentially only exposing one generic, and that's the Item type.

---

I suspect what's left to do is to somehow hack Throw() around accepting IEnumerable<T> as its entry parameter. Could you please @amantinband advise us on how feasible this would be, in regards to the library itself, and how you've planned its development this far?

[Mitchman215]

Any update on this? It would be really useful to have this feature.