Improve readability of "assert failed" message for DictionaryContainsKeyValuePairConstraint WithValue()

[GustaMagik]

Request for improvement of the assert message for .WithValue(), introduced in #3486

Current

Message: 
      Expected: dictionary containing entry System.Collections.DictionaryEntry
      But was:  < ["firstname", "Jane"], ["lastname", "Doe"] >

Preferred

Message: 
      Expected: dictionary containing entry ["firstname", "John"]
      But was:  < ["firstname", "Jane"], ["lastname", "Doe"] >

This would bring the message more in line with that of Contains.Key / Contains.Value

Message:
      Expected: dictionary containing key "email"
      But was:  < ["firstname", "Jane"], ["lastname", "Doe"] >

[mikkelbu]

I think this improvement makes sense.

[manfred-brands]

I stumbled into the same issue today and was about to create a ticket. Luckily I looked first.

System.Collection.DictionaryEntry has no ToString() overload and hence prints the type name.

Am I right that all that needs doing is add a formatter to MsgUtils like:

AddFormatter(next => val => val is DictionaryEntry de ? FormatKeyValuePair(de.Key, de.Value) : next(val));

It seems to work:

Error Message:
Expected: dictionary containing entry [123, <Classes.NUnit.Class1Fixture>]
But was: < [123, <Classes.Class1>], [234, <Classes.Class2>] >

I will raise a PR.

[benrobot]

I'm running nunit 3.13.3 which was released in Mar 2022 and #3778 was merged nearly a year before 3.13.3 was released.

Couldn't this change have been included in version 3.x.x? It doesn't seem like a breaking change.