Automatically detect if private feed is required (#16)

AspNetCoreSdkTests/AspNetCoreSdkTests.csproj

@@ -11,6 +11,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.8.0" />
+    <PackageReference Include="Newtonsoft.Json" Version="11.0.2" />
     <PackageReference Include="NuGet.Versioning" Version="4.7.0" />
     <PackageReference Include="NUnit" Version="3.10.1" />
     <PackageReference Include="NUnit3TestAdapter" Version="3.10.0" />

AspNetCoreSdkTests/TemplateTests.cs

@@ -130,7 +130,7 @@ namespace AspNetCoreSdkTests
                 NuGetPackageSource.NuGetOrg : NuGetPackageSource.None;
 
             // Pre-release SDKs require a private nuget feed
-            var onlinePackageSource = DotNetUtil.IsPreReleaseSdk ?
+            var onlinePackageSource = DotNetUtil.RequiresPrivateFeed ?
                 NuGetPackageSource.EnvironmentVariableAndNuGetOrg : NuGetPackageSource.NuGetOrg;
 
             if (runtimeIdentifier == RuntimeIdentifier.None)

AspNetCoreSdkTests/Util/DotNetUtil.cs

@@ -1,9 +1,12 @@
 using Microsoft.Extensions.Internal;
+using Newtonsoft.Json;
 using NuGet.Versioning;
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.IO;
+using System.Linq;
+using System.Net.Http;
 using System.Text.RegularExpressions;
 using System.Threading;
 
@@ -33,12 +36,14 @@ namespace AspNetCoreSdkTests.Util
 
         public static SemanticVersion RuntimeVersion => _versions.Value.RuntimeVersion;
 
-        public static bool IsPreReleaseSdk =>
+        private static readonly Lazy<bool> _requiresPrivateFeed = new Lazy<bool>(GetRequiresPrivateFeed, LazyThreadSafetyMode.PublicationOnly);
-            SdkVersion.IsPrerelease ||
+
-            SdkVersion == new SemanticVersion(2, 1, 402);
+        public static bool RequiresPrivateFeed => _requiresPrivateFeed.Value;
 
         public static string TargetFrameworkMoniker => $"netcoreapp{RuntimeVersion.Major}.{RuntimeVersion.Minor}";
 
+        private static readonly HttpClient _httpClient = new HttpClient();
+
         private static (SemanticVersion SdkVersion, SemanticVersion RuntimeVersion) GetVersions()
         {
             var info = RunDotNet("--info", workingDirectory: null);
@@ -60,6 +65,16 @@ namespace AspNetCoreSdkTests.Util
             }
         }
 
+        // Private feed is required if nuget.org doesn't contain the matching version of Microsoft.NETCore.App
+        private static bool GetRequiresPrivateFeed()
+        {
+            var versionString = _httpClient.GetStringAsync("https://api.nuget.org/v3-flatcontainer/microsoft.netcore.app/index.json").Result;
+            var definition = new { Versions = Enumerable.Empty<string>() };
+
+            var versions = JsonConvert.DeserializeAnonymousType(versionString, definition);
+            return !versions.Versions.Contains(RuntimeVersion.ToString());
+        }
+
         private static IEnumerable<KeyValuePair<string, string>> GetEnvironment(NuGetPackageSource nuGetPackageSource)
         {
             // Set NUGET_PACKAGES to an initially-empty, distinct folder for each NuGetPackageSource.  This ensures packages are loaded