Support for ILookup<,>

We recently added built-in support for IReadOnlyList<> (#941), IReadOnlyDictionary<,> (#980) and ISet<> (#983).

The one left out is ILookup<,>.

Unluckily this is a tricky one because there is only one implementation (Lookup<TKey, TValue> and this one has no public constructor.

I have a working customization for a closed generic form but I wonder if it can be reimplemented so that it works for open generics and then can be added to the default registration.

fixture.Customize<ILookup<string, int>>(c => c.FromFactory((IDictionary<string, IEnumerable<int>> input) => input.SelectMany(i => i.Value, (item, value) => new { key = item.Key, value }).ToLookup(k => k.key, v => v.value)));

[zvirja]

@moodmosaic Thanks for your thoughts, they confirmed my initial intention 😃

@Kralizek Given that there is a relatively simple way to enable this feature in your solution, would you be fine if we close this issue for now? If later there are more requests for it, we could re-open it again.

[zvirja]

Well, it’s impossible to remove issues from GitHub. Even after I close it, you can still find it using the Search and use the code sample above.

Therefore, you will have ages to copy the sample above 😄