Support indexer with multiple arguments

[idigra]

This PR contains support in multiple arguments.

1. Fix null reference exception in case of multiple arguments indexer.
2. Proposal for new API method SetupSetMethod which allows using It.IsAny for the indexer arguments (can be used also for properties, although existing API already covers properties). This is only in proposal level, should be enhanced (documentation, overloading for any count of indexer arguments, exceptions on illegal input).

[stakx]

Hi @idigra, and thanks for this PR, too. Same as with the earlier one from today, I'll try to find some time for reviewing this soon.

Fix null reference exception in case of multiple arguments indexer.

Which null reference exception are we talking about here? Could you post an issue with repro code (or refer me to an existing closed issue)?

Proposal for new API method SetupSetMethod [...]

It shouldn't be necessary to introduce a SetupSetMethod. You'll find that the existing Setup, SetupGet, SetupSet etc. methods already try to recognize when they are called on indexers—indexers shouldn't have their own dedicated methods, from a user's perspective that doesn't make much sense. (SetupGet and SetupSet are probably already confusing enough.)

The problem with It.IsAny and SetupSet would be easily solvable by bringing back the old, deprecated SetupSet overload that takes two expressions: one for the property/indexer to be set up, and one for the value. But unfortunately, that overload has been marked deprecated. I think we should rather de-deprecate the existing method, instead of introducing a new one (if we do something at all).

[idigra]

Which null reference exception are we talking about here? Could you post an issue with repro code (or refer me to an existing closed issue)?

I added a test in the PR that reproduces the bug, named CallbackWithMultipleArgumentIndexerSetterWithoutAny. Now there's an issue #695 :)

I think we should rather de-deprecate the existing method, instead of introducing a new one (if we do something at all).

Why not? I think it's a useful scenario.
(BTW, even if you think not to de-deprecate, we should solve following issue: #696).

[idigra]

I now see that the second issue I opened (#696, mentioned above) is a duplicate of #218 which is closed in favor of #414. I couldn't find the reason why the SetupSet overload you mentioned was deprecated. Also consider the solution I proposed in my issue #696.

[stakx]

I couldn't find the reason why the SetupSet overload you mentioned was deprecated.

I don't know the exact reason, either. I am guessing that this decision was made simply because being able to write SetupSet(m => m.Something = value) is nicer than SetupSet(m => m.Something, () => value).

[stakx]

Thanks again for your PR! 👍

I'd appreciate if we could focus only on your PR's first stated goal, i.e. fixing the NullReferenceException when setting up an indexer with more than one index parameter. This is the reason why I'm asking you (below) to remove everything related to SetupSetMethod.

I'm happy to discuss SetupSetMethod / the deprecated SetupSet overload / improvements of the current implementation of SetupSetImpl in a separate issue, if you'd like.

Also, please add an entry for your bug fix to CHANGELOG.md:

 # Moq Changelog

 All notable changes to this project will be documented in this file.

 The format is loosely based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).


+## Unreleased
+
+#### Fixed
+
+* Short description of your bugfix (@idigra, #694)
+
+
 ## 4.10.0 (2018-09-08)

[stakx]

Sorry for being quiet so long. All good to go now. I'll update the changelog for you.

[stakx]

@idigra, Moq 4.10.1, which includes your bugfix, has just been published on NuGet.

[idigra]

Thanks. I finally came to verify it, but then I understand that without extending the API to support Any matcher in indexer argument I can't really reach a scenario in which the bug was reproduced.
I would be happy to check it if you have a real scenario in which the bug occurs.

[stakx]

I can't really reach a scenario in which the bug was reproduced.

Sorry, it's been a while, and there's not much context here. Which bug exactly are you referring to?

[idigra]

#696