How do I run tests on my dnx50 project against dnx451?

Question

For one of my projects, I need to downgrade entity framework from 7 to 6, and in order to do that, I need to use dnx451, instead of dnx50 (I think that's how that works anyway, I think 451 is the .net one below 50? idk).

Anywho, for that project, I have this dependency that I extracted to its own project, called csharp_extensions, and that dependency is what I want to have work with both dnx50 and dnx451.

Here is my project.json from my local csharp_extensions:

{
    "version": "1.1.0",
    "configurations": {
        "Debug": {
            "compilationOptions": {
                "define": [ "DEBUG", "TRACE" ]
            }
        },
        "Release": {
            "compilationOptions": {
                "define": [ "RELEASE", "TRACE" ],
                "optimize": true
            }
        }
    },
    "dependencies": {
        "Microsoft.Extensions.PlatformAbstractions": "1.0.0-rc1-final",
        "System.Reflection": "4.1.0-beta-*",
        "xunit": "2.1.0-*",
        "xunit.runner.dnx": "2.1.0-*"
    },
    "commands": {
        "run": "csharp_extensions",
        "test": "xunit.runner.dnx"
    },
    "frameworks": {
        "dnx541": {
            "dependencies": {
                "Microsoft.CSharp": "4.0.1-beta-23516",
                "System.Collections": "4.0.11-beta-23516",
                "System.Linq": "4.0.1-beta-23516",
                "System.Runtime": "4.0.21-beta-23516",
                "System.Threading": "4.0.11-beta-23516"
            }
        },
        "dnxcore50": {
            "_": "this is the recommended windows runtime",
            "dependencies": {
                "System.Console": "4.0.0-beta-*",
                "System.Reflection.TypeExtensions": "4.1.0-beta-*",
                "System.Runtime.Extensions": "(4.0,]",
                "System.Dynamic.Runtime": "(4.0.0,]",
                "Microsoft.CSharp": "(4.0.0,]",
                "System.IO": "(4.0,]"
            }
        }

    },
}

and here is the project.json that works (for dnx50 only though) https://github.com/NullVoxPopuli/csharp-extensions/blob/master/project.json it's the same as what is pasted above, but no entry for dnx541.

With the above (pasted) project.json, when I try to build, it says everything succeeded, but when tests run, I get the following error:

------ Discover test started ------
------ Test started: Project: csharp-extensions ------
Starting  Microsoft.Dnx.TestHost [C:\Users\me\.dnx\runtimes\dnx-clr-win-x86.1.0.0-rc1-update1\bin\dnx.exe --appbase "C:\Users\me\Development\csharp-extensions" Microsoft.Dnx.ApplicationHost --port 32182 Microsoft.Dnx.TestHost --port 36832 --parentProcessId 21136]

System.InvalidOperationException: The current runtime target framework is not compatible with 'csharp-extensions'.
Current runtime target framework: 'DNX,Version=v4.5.1 (dnx451)'
 Version:      1.0.0-rc1-16231
 Type:         Clr
 Architecture: x86
 OS Name:      Windows
 OS Version:   6.3
 Runtime Id:   win81-x86

Please make sure the runtime matches a framework specified in project.json
   at Microsoft.Dnx.ApplicationHost.DefaultHost.GetEntryPoint(String applicationName)
   at Microsoft.Dnx.ApplicationHost.Program.ExecuteMain(DefaultHost host, String applicationName, String[] args)
   at Microsoft.Dnx.ApplicationHost.Program.Main(String[] args)
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at Microsoft.Dnx.Runtime.Common.EntryPointExecutor.Execute(Assembly assembly, String[] args, IServiceProvider serviceProvider)
   at Microsoft.Dnx.Host.Bootstrapper.RunAsync(List`1 args, IRuntimeEnvironment env, String appBase, FrameworkName targetFramework)
   at Microsoft.Dnx.Host.RuntimeBootstrapper.ExecuteAsync(String[] args, BootstrapperContext bootstrapperContext)
   at Microsoft.Dnx.Host.RuntimeBootstrapper.Execute(String[] args, BootstrapperContext bootstrapperContext)
Unable to start Microsoft.Dnx.TestHost
========== Discover test finished: 0 found (0:00:01.0852529) ==========

I'm pretty new to dnvm, and the commands don't make a whole lot of sense to me as far as being easy to remember (I'm used to rvm, from the ruby world, though)

Answer 1

"frameworks": {
    "dnx541": {
        …

You accidentally misspelt the framework version there. It should be 451 (as you correctly mentioned multiple times in your question), not 541. So since you're running this with the dnx451 framework (as specified in the error message), DNX will look for that framework in the configuration but cannot find it.