Convert Portable library to .NET Standard 1.3

[rprouse]

The portable library is .NET Standard 1.3 (or possibly 1.0 or 1.1), but it cannot easily be installed in a .NET Standard 1.3 project. Attempting to do so results in the following error,

Restoring packages for C:\src\spikes\NetstandardLibrary\NetstandardLibrary\NetstandardLibrary.csproj...
Package NUnit 3.6.1 is not compatible with netstandard1.3 (.NETStandard,Version=v1.3). Package NUnit 3.6.1 supports:
  - monoandroid (MonoAndroid,Version=v0.0)
  - net20 (.NETFramework,Version=v2.0)
  - net35 (.NETFramework,Version=v3.5)
  - net40 (.NETFramework,Version=v4.0)
  - net45 (.NETFramework,Version=v4.5)
  - netstandard1.6 (.NETStandard,Version=v1.6)
  - portable-net45+win8+wp8+wpa81 (.NETPortable,Version=v0.0,Profile=Profile259)
  - xamarinios10 (Xamarin.iOS,Version=v1.0)
One or more packages are incompatible with .NETStandard,Version=v1.3.
Package restore failed. Rolling back package changes for 'NetstandardLibrary'.

If we convert the project to the lowest .NET Standard version it supports instead of PCL, it will still work in all the PCL targets, plus it will work in .NET Standard.

Before we do this, can anyone see any issues with this approach?

[rprouse]

I should also state that I don't want to drop the 1.6 version as it adds back in functionality that is not available in the portable library or .NET Standard 1.3. I see them as complimenting each other.

[CharliePoole]

Seems like a good way to go.

[ChrisMaddock]

Sounds good to me.

[jnm2]

I like it. According to @codito, netstandard1.0 is identical to what portable is currently targeting.

[rprouse]

@jnm2 I was hoping to target 1.0 if possible, 1.3 if not.

[jnm2]

@rprouse That sounds good. Since all the APIs in the portable project's current target are also in netstandard1.0, I would not expect a need to go higher.

[NN---]

@rprouse What is the latest NUnit version supporting .NET Standard 1.0 ?

[jnm2]

@NN--- We supported Profile259 which is equivalent to .NET Standard 1.0 (https://docs.microsoft.com/en-us/dotnet/standard/net-standard#pcl-compatibility) up to and including https://www.nuget.org/packages/NUnit/3.6.1 and then switched to .NET Standard 1.3 in 3.7.

The only use for .NET Standard 1.0-1.3 is if you target the discontinued Windows 8/Windows Phone 8/Windows Phone Silverlight frameworks:
https://docs.microsoft.com/en-us/dotnet/standard/net-standard#net-implementation-support

[NN---]

I tried to install 3.6.1 on .NET Standard 1.2 and it didn't work for me.

[jnm2]

@NN--- Where was the failure and what was the message?

[NN---]

NU1202: Package NUnit 3.5.0 is not compatible with netstandard1.2 (.NETStandard,Version=v1.2). Package NUnit 3.5.0 supports:
  - dotnet (.NETPlatform,Version=v5.0)
  - net20 (.NETFramework,Version=v2.0)
  - net35 (.NETFramework,Version=v3.5)
  - net40 (.NETFramework,Version=v4.0)
  - net45 (.NETFramework,Version=v4.5)
  - portable-net45+win8+wp8+wpa81 (.NETPortable,Version=v0.0,Profile=Profile259)

[theraot]

This is the problem: dotnet/sdk#391

We got it installed with the workaround described there