Testing for .NET family

frameworkdescription.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFrameworks>netcoreapp3.1;net5.0;net48</TargetFrameworks>
  </PropertyGroup>

</Project>

Program.cs

using System;
using System.Runtime.InteropServices;

namespace frameworkdescription
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine($"{nameof(Environment.Version)}: {Environment.Version}");
            Console.WriteLine($"{nameof(RuntimeInformation.FrameworkDescription)}: {RuntimeInformation.FrameworkDescription}");

            if (Environment.Version.Major >= 5)
            {
                Console.WriteLine($"This is .NET {Environment.Version}");
            }
            // This test for .NET Core only works for 3.0+
            // Context: https://github.com/dotnet/runtime/issues/12124
            else if (RuntimeInformation.FrameworkDescription.StartsWith(".NET Core"))
            {
                Console.WriteLine($"This is .NET Core {Environment.Version}");
            }
            else if (Environment.Version.Major < 5)
            {
                Console.WriteLine($"This is .NET Framework {Environment.Version}");
            }

            // Some folks want a simple "is .NET Core" check.
            var isDotnetCore = Environment.Version.Major >= 5 || RuntimeInformation.FrameworkDescription.StartsWith(".NET Core");

            if (isDotnetCore)
            {
                Console.WriteLine("This is .NET Core");
            }
        }
    }
}

Results:

PS D:\git\testapps\frameworkdescription> dotnet run -f net5.0
Version: 5.0.0
FrameworkDescription: .NET 5.0.0-rc.2.20475.5
This is .NET 5.0.0
This is .NET Core
PS D:\git\testapps\frameworkdescription> dotnet run -f netcoreapp3.1
Version: 3.1.7
FrameworkDescription: .NET Core 3.1.7
This is .NET Core 3.1.7
This is .NET Core
PS D:\git\testapps\frameworkdescription> dotnet run -f net48
Version: 4.0.30319.42000
FrameworkDescription: .NET Framework 4.8.4261.0
This is .NET Framework 4.0.30319.42000