Add Message tests

[hughbe]

• Firstly, remove the dud methods UnsafeMethods.PtrToStructure/UnsafeMethods.StructureToPtr/UnsafeMethods.SizeOf as just call the equivalent Marshal method.
• Use generic PtrToStructure
• Make structCache.GetStruct generic to avoid so much casting
• Refactor out WM_* and EM_* messages to avoid code duplication and extract them from the massive NativeMethods etc files and to match interop guidelines
• Add unit tests for Message class, especially Message.ToString

[codecov]

Codecov Report

Merging #791 into master will increase coverage by 0.26702%.
The diff coverage is 66.13885%.

@@                Coverage Diff                 @@
##              master       #791         +/-   ##
==================================================
+ Coverage   27.70557%   27.9726%   +0.26703%     
==================================================
  Files           1061       1062          +1     
  Lines         291667     292311        +644     
  Branches       38514      38514                 
==================================================
+ Hits           80808      81767        +959     
+ Misses        206797     206487        -310     
+ Partials        4062       4057          -5

Flag	Coverage Δ
#Debug	27.9726% <66.13885%> (+0.26702%)	⬆️
#production	18.33984% <54.3514%> (+0.19435%)	⬆️
#test	98.65933% <100%> (+0.01617%)	⬆️

[JeremyKuhne]

Thanks! I think we should consider making these enums in the future as I believe that would reduce the size of the assembly (see my inline comment).

[JeremyKuhne]

This code makes me think it might be better to change all of these consts into enums and use reflection to get the name. I think overall we'd be reducing the size of the assembly by something measurable.

[hughbe]

@zsd4yr I like this, and it wouldn't be too hard to do that in this PR.

One question - currently some window messages are commented out. Previously they'd return the hex value of the id in the Decode method, but now a string name would be returned. This actually seems quite good, right - is this a good change?

[zsd4yr]

@hughbe, I am unfamiliar with the change you're asking about. Could you give me an example and let me know who the author is in the git blame? Has this been the case since we wen't open? If so, I can followup by "git blaming" in our previous system to discern why the change was made.

[hughbe]

Ignore me - I'm confused. Essentially I think @JeremyKuhne said that we should put this in an enum them use Enum.GetName(typeof(Interop.WindowMessages), id) in MessageDecoder. I pointed out that there isn't exact a one-to-one mapping between MessageDecoder and the values defined in Interop.WindowMessages or Interop.EditMessages

[JeremyKuhne]

we should put this in an enum them use Enum.GetName(typeof(Interop.WindowMessages), id)

Yes, that is what I'm saying. It should cut the assembly size down. It's also nice when debugging to be able to see the name.

there isn't exact a one-to-one mapping

What doesn't match? We can update the names or special case.

[hughbe]

Rebased - sorry for tall the force pushing :( Seems like there's been loads of PRs that sort of overlap but don't really that get in the way!

[zsd4yr]

@hughbe would you mind adding a description with a summary of the changes you intend here?

Do we want to further separate out Native Methods and Unsafe Native Methods?

[hughbe]

Do we want to further separate out Native Methods and Unsafe Native Methods?

Yes! But thats going to be a gradual cleanup process

[hughbe]

Rebased... again :((