Add collection assertion ContainEquivalentOf

[matthiaslischka]

I gave #584 a try.
A new collection assertion named ContainEquivalentTo so a collection can be asserted to contain an object that "IsEquivalentTo" an expected object.
Not sure about the documentation. Could be enough, but not sure.

BR Matthias

[dennisdoomen]

See http://dawehner.github.io/github,/code/review/2017/09/08/emoji-code-review.html for the meaning of the emojis

[dennisdoomen]

Just two typos. The rest looks good.

[jnyrup]

Should this be added to GenericDictionaryAssertions.cs as well?

[dennisdoomen]

Should this be added to GenericDictionaryAssertions.cs as well?

To verify that a dictionary contains a key-value pair which value is equivalent to the provided expectation? Maybe, but I don't think it belongs in this PR. It's not a consistency thing IMO.

[jnyrup]

Ahh, yes of course.
I just searched for assertion classes exposing BeEquivalentTo, for consistency matters.

If one wants to assert that a dictionary contains an equivalent value, one can use

dictionary.Values.Should().ContainEquivalentOf(expected);

[dennisdoomen]

So it seems we can merge this one.

[jnyrup]

I agree. I haven't been able to come up with a reason not to merge it.

[matthiaslischka]

Hi, i just wanted to thank the two of you for your support with this PR. Especially @dennisdoomen, you made me realize just how much work maintaining an open source project is as you could have done this by yourself in no time but took the effort to support me in my doing. Thanks.

[dennisdoomen]

Thanks for the kind words.