c# - Pain-free local development while also referencing NuGet packages

Question

I am attempting to publish and consume versioned NuGet packages of class libraries while avoiding headaches for local development. Here is a sample Visual Studio solution layout:

| Libraries
  | LibraryA
  | LibraryB
  | LibraryC
| Applications
  | ApplicationD
  | ApplicationE

This is a single solution containing both shared class libraries and multiple applications. Currently references to the class libraries by the applications are local in-solution references.

What I would like to do is to publish the libraries (A,B,C) as versioned NuGet packages which are then referenced by the applications as needed (D,E). This allows a change to a shared library to be independent from an update to an application which is deployed. Without this, changing one library could cause the binaries to change in a dozen or more applications, all of which would technically need to be tested. This is undesirable, and versioning with NuGet fixes this.

However, let us say that I want to update the content of LibraryA and ApplicationD at the same time. In order to do this after we have switched to NuGet, I will have to make changes to LibraryA, commit them, wait for the package to be created, tell ApplicationD to update its reference to LibraryA, and then test or develop in ApplicationD. This is far more complicated than simply working with both at the same time using local in-solution references.

What is a better way to get both the robustness of versioned NuGet packages for my shared class libraries while also keeping development simple even if it spans over multiple projects and applications? The only other solutions I have found all involve too much overhead or headache, such as having to constantly change the references for ApplicationD between the NuGet package and the local project.

EDIT: To clarify the premise, this question assumes the following:

• The architecture (solution and project organization) cannot be significantly reorganized
• Shared libraries are going to change at a non-trivial frequency
• Changing a shared library cannot force any application to be updated
• Applications can reference different versions of shared libraries

Answer 1

Although it takes some work, it is possible to hand-edit .csproj files in order to set up conditional referencing by adding a Condition attribute to the appropriate references.

EDIT I've moved these conditions into ItemGroups, as it seems this is how my mentioned production code is working, and there has been mention of this being a possible issue in VS 2013.

<ItemGroup Condition="'$(Configuration)' == 'Debug Local'">
    <!-- Library A reference as generated by VS for an in-solution reference, children unmodified -->
    <ProjectReference>...
</ItemGroup>

<ItemGroup Condition="'$(Configuration)' == 'Debug NuGet'">
    <!-- Library A reference as generated by NuGet, child nodes unmodified --> 
    <Reference Include="LibraryA">...
</ItemGroup>

This would allow you to have, on the Projects D & E, configurations of "Debug NuGet" vs. "Debug Local" which reference the libraries differently. If you then have multiple solution files which have their configurations mapped to the appropriate configurations on the projects within, the end user would never see more than "Debug" and "Release" for most operation, since those are the solution configs, and would only need to open the full solution for editing the A, B, & C projects.

Now, as for getting the A, B, & C projects out of the way, you could set them up under a folder marked as a subrepo (assuming you're using an SCM that supports this, such as Git). Most users would never need to pull the subrepo since they're not accessing the ABC projects, and are instead grabbing from NuGet.

Maintenance wise, I can guarantee that VS will not edit the conditional references, and will respect them during compilation -I have gone through both VS 2010 and 2013 (EDIT: Professional version, though I have delved into doing the same with express) with the same conditional reference projects at work. Keep in mind than in VS, references can be made version-agnostic, making NuGet the only place from which version need be maintained, and that can be done like any other NuGet package. While I'm hopeful, I have NOT tested whether NuGet will fight with the conditional references.

EDIT It may also be prudent to note that conditional references can cause warnings about missing DLLs, but does not actually hinder compilation or run.

EDIT For those still reading this, I'm now (7/2019) hearing that the IDE isn't as friendly to these changes anymore, and either it or the Package Manager may override them. Proceed with caution, and always read your commits!